File: Notes.html

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dar 2.6.13-2
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
    <title>DAR/LIBDAR Internals - Notes</title>
  </head>
  <body style="background-color: rgb(221, 221, 221); color: rgb(0, 0, 170);" vlink="#000055"
    link="#0000ff" alink="#ff0000">
    <center>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top; width: 161px;"><a href="index.html"><img
                  style="border: 0px solid ; width: 160px; height: 120px;" alt="Dar Documentation"
                  src="dar_s_doc.jpg"></a><br>
            </td>
            <td style="vertical-align: top;">
              <h1 style="text-align: center;"><br>
              </h1>
              <h1 style="text-align: center;">Dar/Libdar Internals - Notes<br>
              </h1>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <br>
      <div style="text-align: center;">
        <hr style="width: 100%; height: 2px;"></div>
      <br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <div style="text-align: justify;">
                <h2>Introduction</h2>
                <div style="text-align: justify; margin-left: 40px;">Here take
                  place a collection of notes. These have been created after
                  implementation of a given feature, mainly for further
                  reference but also for user information. The ideas behind
                  these notes are to remind some choices of implementation, the
                  arguments that lead to this choices in on side, and in the
                  other side let the user have a room to be informed on the
                  choices done and be able to bring his remarks without having
                  to deeply look in the code to learn dar's internals.<br>
                </div>
              </div>
              <h2>Contents</h2>
              <div style="margin-left: 40px;"><a href="#EA_and_diff">EA &amp;
                  differential backup</a><span style="font-weight: bold;"></span><span
                  style="font-weight: bold;"></span><span style="font-weight: bold;"></span><br>
                <span style="font-weight: bold;"></span><a href="#archive_structure">Archive
structure
                  in brief</a><br>
                <span style="font-weight: bold;"></span><a href="#scrambling">Scrambling</a><br>
                <span style="font-weight: bold;"></span><a href="#overflow">Overflow
in
                  arithmetic integer operations</a><span style="font-weight: bold;"></span><br>
                <span style="font-weight: bold;"></span><span style="font-weight: bold;"></span><span
                  style="font-weight: bold;"></span><a href="#strong_encryption">Strong
                  encryption</a><br>
                <a href="#thread_safe">libdar and thread-safe requirement</a><span
                  style="font-weight: bold;"></span><br>
                <span style="font-weight: bold;"></span><a href="#dar_manager_deleted">Dar_manager
and
                  delete files</a><span style="font-weight: bold;"></span><br>
                <span style="font-weight: bold;"></span><a href="#NLS">Native
                  Language Support / gettext / libintl</a><br>
                <a href="#Dar_relase_Process_in_brief">Dar Release Process</a><br>
                <a href="#Dar_version_naming">Dar's Versions</a><br>
                <a href="#sym">How symmetric encryption is performed in
                  dar/libdar</a><br>
                <a href="#asym">How asymmetric encryption is performed in
                  dar/libdar</a><br>
                <br>
              </div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;">
      <h3><a name="EA_and_diff"></a></h3>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>EA &amp; differential backup</h3>
              <h4>Brief presentation of EA:</h4>
              <div style="margin-left: 40px;">
                <div style="text-align: justify;">EA stands for Extended
                  Attributes. In Unix filesystem a regular file is composed of a
                  set of byte (the data) and an inode. The inode add properties
                  to the file, such as owner, group, permission, dates (last
                  modification date of the data [mtime], last access date to
                  data [atime], and last inode change date [ctime]), etc). Last,
                  the name of the file is not contained in the inode, but in the
                  directory(ies) it is linked to. When a file is linked more
                  than once in the directory tree, we speak about "hard links".
                  This way the same data and associated inode appears several
                  time in the same or different directories. This is not the
                  same as a symbolic links, which is a file that contains the
                  path to another file (which may or may not exist). A symbolic
                  link has its own inode. OK, now let's talk about EA: <br>
                </div>
                <br>
              </div>
              <div style="text-align: justify; margin-left: 40px;">Extended
                attributes is a recent feature of Unix file system (at the time
                of the writing, year 2002). They extend attributes provided by
                the inode and associated to a data. They are not part of the
                inode, nor part of the data, nor part of a given directory. They
                are stored beside the inode and are a set of pair of key and
                value. The owner of the file can add or define any key and
                eventually associate data to it. It can also list and remove a
                particular key. What they are used for ? A way to associate
                information to a file. <br>
                <br>
                One particular interesting use of EA, is ACL: Access Control
                List. ACL can be implemented using EA and add a more fine grain
                in assigning access permission to file. For more information one
                EA and ACL, see the site of Andreas Grunbacher: <br>
                <br>
                <div style="margin-left: 40px;"><a href="http://acl.bestbits.at/">http://acl.bestbits.at/</a><br>
                </div>
              </div>
              <h4>EA &amp; Differential Backup</h4>
              <div style="text-align: justify; margin-left: 40px;">to determine
                that an EA has changed dar looks at the ctime value. if ctime
                has changed, (due to EA change, but also to permission or owner
                change) dar saves the EA. ctime also changes, if atime or mtime
                changes. So if you access a file or modify it, dar will consider
                that the EA have changed also. This is not really fair, I admit.<br>
                <br>
                Something better would be to compare EA one by one, and record
                those that have changed or have been deleted. But to be able to
                compare all EA and their value reference EA must reside in
                memory. As EA can grow up to 64 KB by file, this can lead to a
                quick saturation of the virtual memory, which is already enough
                solicited by the catalogue. <br>
                <br>
                These two schemes implies a different pattern for saving EA in
                archive. In the first case (no EA in memory except at time of
                operation on it), to avoid skipping in the archive (and ask the
                user to change of disks too often), EA must be stored beside the
                data of the file (if present). Thus they must be distributed all
                along the archive (except at the end that only contains the
                catalogue).<br>
                <br>
                In the second case (EA are loaded in memory for comparison), EA
                must reside beside or within the catalogue, in any case at the
                end of the archive, not to have to user to need all disks to
                just take an archive as reference.<br>
                <br>
                As the catalogue, grows already fast with the number of file to
                save (from a few bytes for hard_link to 400 bytes around per
                directory inode), the memory saving option has been adopted.<br>
                <br>
                Thus, EA changes are based on the ctime change. Unfortunately,
                no system call permits to restore ctime. Thus, restoring a
                differential backup after its reference has been restored, will
                present restored inode as more recent than those in the
                differential archive, thus the -r option would prevent any EA
                restoration. In consequence, -r has been disabled for EA, it
                does only concern data contents. If you don't want to restore
                any EA but just more recent data, you can use the following : -r
                -u "*"</div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><a name="archive_structure"></a><br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Archive structure in brief</h3>
              <br>
              <h4>The Slice Level</h4>
              <div style="margin-left: 40px;">A slice is composed of a header,
                data and trailer (the trailer appeared with archive format
                version 8)<br>
              </div>
              <br>
              <div style="text-align: justify; margin-left: 80px;"><code>+--------+-------------------------------------------+-------+</code><br>
                <code>| header |&nbsp;
                  Data&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |Trailer|</code><br>
                <code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |</code><br>
                <code>+--------+-------------------------------------------+-------+</code><br>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><br>
                the<span style="font-weight: bold;"> </span><span style="text-decoration: underline; font-weight: bold;">slice
                  header</span><span style="font-weight: bold;"> </span>is
                composed of<br>
              </div>
              <ul style="text-align: justify; margin-left: 40px;">
                <li>a magic number that tells this is a dar slice</li>
                <li>a internal_name which is unique to a given archive and
                  shared by all slices<br>
                </li>
                <li>a flag that tells whether the slice is the last of the
                  archive or whether a trailer is present that contains this
                  info.<br>
                </li>
                <li>a extension flag, that was used in older archive but which
                  now always set to 'T' telling that a TLV list follows</li>
                <li>A TLV (Type Length Value) list of item, it contains:</li>
                <ul>
                  <li>the slice size</li>
                  <li>first slice size</li>
                  <li>the data_name.&nbsp;</li>
                </ul>
              </ul>
              <div style="margin-left: 80px;">The TLV list will receive any
                future new field related to slice header.<br>
                <br>
              </div>
              <div style="text-align: justify; margin-left: 80px;"><code>+-------+----------+------+-----------+-------+</code><br>
                <code>| Magic | internal | flag | extension | TLV&nbsp;&nbsp; |<br>
                </code> <code>| Num.&nbsp; | name&nbsp;&nbsp;&nbsp;&nbsp; |
                  byte | byte&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | list&nbsp; |</code><br>
                <code>+-------+----------+------+-----------+-------+</code><br>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><br>
                <div style="text-align: justify;">The header is the first thing
                  to be written, and if the current slice is not the last slice
                  (all data to write could not fit in it), before format 8, the
                  flag field was changed indicating that another slice follows.
                  Since archive format 8, the flag is set to a specific value
                  indicating that the information telling whether the slice is
                  the last or not is placed in a slice trailer, a new
                  "structure" that appeared with that format and which is
                  located at the end of each slice.<br>
                  <br>
                  The header is also the first part to be read.<br>
                </div>
                <br>
                A TLV list is of course a list of TLV:<br>
                <br>
                <div style="margin-left: 40px;"><code>+-------+----------+------+-----------+-
                    ...-----+-------+</code><br>
                  <code>| Number| TLV 1 &nbsp;&nbsp; | TLV 2| TLV 3 &nbsp;
                    &nbsp;
                    |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |
                    TLV n |</code><br>
                  <code> </code><code>| of TLV| &nbsp; &nbsp; &nbsp;
                    &nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                    |&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;
                    |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;
                    |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                  <code>+-------+----------+------+-----------+--...-----+-------+<br>
                    <br>
                  </code></div>
              </div>
              <div style="text-align: justify;">
                <div style="margin-left: 40px;">Each TLV item is, as commonly,
                  defined as set of three fields:<br>
                  <br>
                  <div style="margin-left: 40px;"><code>+---------+-------------------------+-------------------------+</code><br>
                    <code>| Type&nbsp;&nbsp;&nbsp; |
                      Length&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                      |
                      Value&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                      |<br>
                      |(2 bytes)| (arbitrary large value) | (arbitrary large
                      data)&nbsp; |</code><br>
                    <code>+---------+-------------------------+-------------------------+</code></div>
                </div>
              </div>
              <div style="text-align: justify; margin-left: 40px;"> <br>
                <div style="text-align: justify;">The 2 bytes type is large
                  enough for today's need (65535 different types while only
                  three used), however TLV 65535 is reserved for future use and
                  will signal a new format for the type field.<br>
                </div>
                <br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">To know in
                which slice and at which position to find a particular data, dar
                needs to know each file's size. This is the reason why each
                slice contains the slice size information, in particular the
                last slice. In older version, dar had to read the first slice
                first to get this slicing information. Then it could read the
                archive contents at the end of the last slice. Today, reading
                the last slice, dar can fetch the slicing scheme from the slice
                header (what we just detailed) and fetch the archive contents at
                the end of this same last slice.<br>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><br>
                <span style="text-decoration: underline; font-weight: bold;">The
                  trailer</span> (which is one byte length) is new since archive
                format version 8 (released 2.4.0). It contains the value that
                was located in the header flag field in older archive format,
                telling whether the slice is the last of the archive or not.
                When writting down a single sliced archive (no -s option
                provided), both the header and the trailer tell that the slice
                is the last of the archive (duplicated information). However,
                when doing multi-sliced archive, it is not possible to known
                whether a slice is the last before reaching the requested amount
                of data per slice (which depends on the amount of byte to save,
                compression ratio, encryption overhead, etc.). Thus the header
                flag contains a value telling that to know whether the slice is
                the last or not, one must read the trailer.<br>
                <br>
                In older format, it was necessary to seek back to update the
                header with the correct information when a new slice had to be
                created. But, keeping this behavior, it would not have been
                possible to make a digest "on the fly" (see --hash option). The
                addition of the trailer was required for that feature: to
                compute a md5 or sha1, ... hash for each slice. But, this costs
                one byte per slice, yes.<br>
              </div>
              <h4>Data Name</h4>
              <div style="margin-left: 40px;">As seen above in the header
                fields, we have among others the three following identifiers:<br>
                <ul>
                  <li>magic number</li>
                  <li>internal name</li>
                  <li>data name<br>
                  </li>
                </ul>
              </div>
              <div style="margin-left: 40px;">
                <div style="text-align: justify;">as already said, magic number
                  is constant and let dar be (almost) sure a given file is a dar
                  slice file, this is also based in particular on that field
                  that the common unix 'file' command identifies an dar archive.
                  Also briefly explained, the internal_name is a identifier that
                  let dar be almost sure that several slices are from the same
                  archive (problem car arise if two archives of same basename
                  have their slices mixed together: dar will see that and report
                  it to the user).<br>
                  <br>
                  The new and not yet described field is the "data_name". The
                  data_name field is also present in the archive catalogue (the
                  table of content) of each archive. It may be the same value as
                  the one in the slice headers (normal archives) or another
                  value if the archive results from a catalogue isolation
                  process.<br>
                  <br>
                  Why this field? A new feature with release 2.4.0 is the
                  ability to use an extracted catalogue to backup a internal
                  catalogue of a given archive. Comparing the data_name value of
                  the catalogue resulting from the isolation operation to the
                  data_name value present int the slices of an archive to
                  rescue, dar can be (almost) sure that the extracted catalogue
                  matches the data present in the archive the user is trying to
                  use it with.<br>
                  <br>
                  In brief:<br>
                </div>
              </div>
              <br>
              <table style="text-align: left; width: 1038px; height: 124px; margin-left: auto; margin-right: 0px;"
                cellspacing="2" cellpadding="2" border="1">
                <tbody>
                  <tr>
                    <td style="vertical-align: top; text-align: center; width: 20%; font-weight: bold;">Fields</td>
                    <td style="vertical-align: top; width: 20%; text-align: center; font-weight: bold;">Normal
                      Archive<br>
                    </td>
                    <td style="vertical-align: top; width: 20%; text-align: center; font-weight: bold;">Resliced
Using
                      dar_xform<br>
                    </td>
                    <td style="vertical-align: top; width: 20%; text-align: center; font-weight: bold;">Resulting
From
                      Isolation<br>
                    </td>
                    <td style="vertical-align: top; text-align: center; width: 20%;">&nbsp;<span
                        style="font-weight: bold;">isolated archive <br>
                        resliced with dar_xform</span><br>
                    </td>
                  </tr>
                  <tr>
                    <td style="vertical-align: top; font-weight: bold;">internal_name
(slice
                      header)<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">B<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">C<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">D<br>
                    </td>
                  </tr>
                  <tr>
                    <td style="vertical-align: top; font-weight: bold;">data_name
(slice
                      header)<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">C<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">C<br>
                    </td>
                  </tr>
                  <tr>
                    <td style="vertical-align: top; font-weight: bold;">data_name
(archive
                      catalogue)<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                    <td style="vertical-align: top; text-align: center;">A<br>
                    </td>
                  </tr>
                </tbody>
              </table>
              <br>
              <h4>Archive Level</h4>
              <div style="margin-left: 40px;">
                <div style="text-align: justify;">The archive level describes
                  the structure of the slice's data field (removing header and
                  trailer of each slice), when they are all sticked together
                  from slice to slice:<br>
                </div>
                <br>
              </div>
              <div style="margin-left: 80px;"><code>+---------+----------------------------+-----------+--------+---------+--------+</code><br>
                <code>| version |&nbsp;&nbsp; Data&nbsp; &nbsp;
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|
                  catalogue | term 1 | version | term 2 |<br>
                  | header&nbsp; </code><code>|
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  | trailer |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>+---------+----------------------------+-----------+--------+---------+--------+</code><br>
              </div>
              <div style="margin-left: 80px;"><code></code></div>
              <div style="margin-left: 40px;"><br>
                The <span style="text-decoration: underline; font-weight: bold;">version
                  header</span> is a short version of the trailer version. It is
                used when reading an archive in sequential mode, to be able to
                prepare the proper compression layer, and known whether escape
                sequence mark are present in the archive.<br>
                <br>
                the <span style="text-decoration: underline; font-weight: bold;">version
                  trailer</span> (which may still be called "version header" in
                some part of the documentation because it was only located at
                the beginning of the archive in previous archive format) is
                composed of:<br>
              </div>
              <ul style="margin-left: 40px;">
                <li>edition version of the archive</li>
                <li>compression algorithm used</li>
                <li>command line used for creating the archive, now known as
                  "user comment"<br>
                </li>
                <li>flag, telling:</li>
                <ul>
                  <li>whether the archive is encrypted, <br>
                  </li>
                  <li>whether it has escape sequence marks, <br>
                  </li>
                  <li>whether the header/trailer contains an encrypted key</li>
                  <li>whether the header/trailer contains the initial offset
                    field</li>
                  <li>whether the archive is signed</li>
                  <li>whether the header/trailer contains the slice layout of
                    the archive of reference<br>
                  </li>
                  <li>whether the archive has salt+iteration count+hash algo for
                    key derivation fonction (KDF)<br>
                  </li>
                </ul>
                <li>initial offset (telling where starts the data in the
                  archive, is only present in the trailer)</li>
                <li>crypto algorithm used (present only if flag tells that the
                  archive is encrypted)</li>
                <li>size of the crypted key that follows (present only if the
                  flag tells an encrypted key is present)</li>
                <li>encrypted key (encrypted by mean of GPG asymetric algorithm,
                  present only if flag says so)</li>
                <li>eventually, salt, iteration_count and hash algo for key
                  derivation fonction (KDF) (used since version 2.6.0 when
                  strong encryption is set)<br>
                </li>
                <li>CRC (Cyclic Redundancy Check) computed on the whole version
                  header or trailer<br>
                </li>
              </ul>
              <div style="margin-left: 80px;"><code>+---------+------+---------------+------+--------+-------+----------+---------------+------------+------+------+-----------+-----+-------+</code><br>
                <code>| edition | algo | command line&nbsp; | flag | initial|
                  crypto| crypted&nbsp; | gnupg crypted |&nbsp; reference | salt
                  | salt | iteration |hash | CRC&nbsp;&nbsp; |<br>
                </code><code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  | offset | algo&nbsp; | key size | sym. key &nbsp;
                  &nbsp;&nbsp; |&nbsp; slicing &nbsp; | size | (KDF)|
                  count(KDF)|(KDF)|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>+---------+------+---------------+------+--------+-------+-------</code><code>---+---------------+------------+------+------+-----------+-----+-------+</code></div>
              <div style="margin-left: 80px;"> </div>
              <div style="margin-left: 40px;"><br>
                <div style="text-align: justify;">The trailer is used when
                  reading an archive in direct access mode, to build the proper
                  compression layer, escape layer (it is needed if mark have
                  been inserted in the archive to un-escape data that could else
                  be taken as an escape sequence mark) and encryption layer.<br>
                </div>
                <br>
                <span style="text-decoration: underline; font-weight: bold;">The
                  data</span> is a suite of file contents, with EA and FSA if
                present. When tape mark is used, a copy of the CRC is placed
                after's file Data and file's EA, to be used when reading the
                archive in sequential mode. This CRC is also dropped into the
                catalogue which takes place at the end of the archive to be used
                when reading the archive in direct access mode (the default).
                Last when delta binary is used, a file signature may follow the
                file's data:<br>
                <br>
              </div>
              <div style="margin-left: 80px;"><code>&nbsp; ....</code><code>--+---------------------+-------+----+----+------------+------------+----+-----------+-----+-....</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp; file1
                  data&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; | delta | EA | FSA|
                  file2 data | file3 data | EA | file4&nbsp;&nbsp;&nbsp;&nbsp; |
                  FSA |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | (may be
                  compressed) | sig &nbsp; |&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp; |(no EA/FSA)
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;
                  |&nbsp;&nbsp;&nbsp; | delta sig |&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;
....--+---------------------+-------+----+----+------------+------------+----+-----------+-----+-....</code><br>
                <code></code></div>
              <div style="margin-left: 40px;">
                <div style="margin-left: 40px;">in the previous archive example,
                  we find:<br>
                  <ul>
                    <li>for file1: his data, a delta signature of this data,
                      Extended Attributes, and File Specific Attributes</li>
                    <li>for file2: only his data, he has no delta signature, no
                      EA no FSA</li>
                    <li>for file3: data and EA</li>
                    <li>for file4: no data, only a delta signature and FSA</li>
                  </ul>
                  file1 shows all fields that can be associated with an inode,
                  but none is mandatory, though if present they always follow
                  this order:<br>
                  <ul>
                    <li><span style="font-weight: bold;">Data</span> or <span style="font-weight: bold;">delta
                        patch</span></li>
                    <li>followed by data/delta patch CRC when tape marks as set<br>
                    </li>
                    <li><span style="font-weight: bold;">Delta signature</span>
                      <br>
                    </li>
                    <li>followed by delta signature CRC when tape marks are set<br>
                    </li>
                    <li><span style="font-weight: bold;">Extended Attributes</span>
                      <br>
                    </li>
                    <li>followed by EA CRC when tape maks are set<br>
                    </li>
                    <li><span style="font-weight: bold;">File Specific
                        Attributes</span> <br>
                    </li>
                    <li>followed by FSA CRC when tape marks are set<br>
                    </li>
                  </ul>
                </div>
                <div style="margin-left: 80px;">More precisely about<span style="font-weight: bold;">
                    delta signature </span>combined with tape marks, there is
                  additional fields present than just the delta sig and its CRC:<br>
                </div>
                <div style="margin-left: 120px;"><code>+------+------+---------------+----------+--------+</code><br>
                  <code>| base | sig&nbsp; | <span style="font-weight: bold;">sig
                      data</span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | <span style="font-weight: bold;">data
                      CRC </span>| result |</code><br>
                  <code>| CRC&nbsp; | size | (if size &gt; 0)
                    |&nbsp;&nbsp;&nbsp; if&nbsp;&nbsp;&nbsp; |&nbsp;
                    CRC&nbsp;&nbsp; |</code><br>
                  <code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                    |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                    |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|
                    size &gt; 0 |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                  <code>+------+------+---------------+----------+--------+</code><br>
                </div>
                <div style="margin-left: 40px;">
                  <ul>
                    <li><span style="font-weight: bold;">base CRC</span> is the
                      CRC of the file that delta signature has been based on,
                      used at restoration time before applying a patch</li>
                    <li><span style="font-weight: bold;">sig size</span> gives
                      the size of the next field, that may be zero if the file
                      does not has signature associated but the file's data is a
                      delta patch and thus base and result CRCs are needed<br>
                    </li>
                    <li><span style="font-weight: bold;">sig data</span> is the
                      delta signature data. This field and the following are the
                      only one present outside the ending catalogue about delta
                      signatures when tape marks are not set.<br>
                    </li>
                    <li><span style="font-weight: bold;">data CRC</span> is the
                      CRC on the previous field "sig data"<br>
                    </li>
                    <li><span style="font-weight: bold;">result CRC</span> is
                      the CRC of the resulting file once patched&nbsp; (to check
                      the patching was successful)</li>
                  </ul>
                </div>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><span style="text-decoration: underline; font-weight: bold;">the
                  catalogue</span>, contains all inode, directory structure and
                hard_links information as well as data and EA CRC. The directory
                structure is stored in a simple way: the inode of a directory
                comes, then the inode of the files it contains, then a special
                entry named "EOD" for End of Directory. Considering the
                following tree:<br>
              </div>
              <div style="margin-left: 40px; text-align: justify;"><br>
              </div>
              <div style="margin-left: 80px; text-align: justify;"><code>&nbsp;-
                  toto</code><br>
                <code>&nbsp;&nbsp;&nbsp; | titi</code><br>
                <code>&nbsp;&nbsp;&nbsp; | tutu</code><br>
                <code>&nbsp;&nbsp;&nbsp; | tata</code><br>
                <code>&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp; | blup</code><br>
                <code>&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp; +--</code><br>
                <code>&nbsp;&nbsp;&nbsp; | boum</code><br>
                <code>&nbsp;&nbsp;&nbsp; | coucou</code><br>
                <code>&nbsp;&nbsp;&nbsp; +---</code><br>
              </div>
              <div style="margin-left: 40px; text-align: justify;"><br>
                it would generate the following sequence for catalogue storage:<br>
                <br>
              </div>
              <div style="margin-left: 80px; text-align: justify;"><code>+-------+------+------+------+------+-----+------+--------+-----+</code><br>
                <code>|&nbsp; toto | titi | tutu | tata | blup | EOD | boum |
                  coucou | EOD |</code><br>
                <code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>+-------+------+------+------+------+-----+------+--------+-----+</code><br>
              </div>
              <div style="margin-left: 40px; text-align: justify;"><br>
                EOD takes on byte, and this way no need to store the full path
                of each file, just the filename is recorded.<br>
                <br>
                <span style="text-decoration: underline; font-weight: bold;">the
                  terminator</span> stores the position of the beginning of the
                catalogue, it is the last thing to be written. Thus dar first
                reads the terminator, then the catalogue. Well, there is now two
                terminators, both are meant to be read backward. The second
                terminator points to the beginning of the "trailer version"
                which is read first in direct access mode. The first terminator
                points to the start of the catalogue, which is read once the
                adhoc compression and encryption layers has been built based on
                the information found on the "trailer version"<br>
              </div>
              <br>
              <h4>All&nbsp; Together</h4>
              <div style="text-align: justify; margin-left: 40px;">Here is an
                example of how data can be structured in a four slice archive:<br>
                <br>
              </div>
              <div style="text-align: justify; margin-left: 80px;"><code>+--------+--------+------------------------+--+</code><br>
                <code>| slice&nbsp; | version|&nbsp; file data +
                  EA&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |Tr|</code><br>
                <code>| header | header
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;
                  |</code><br>
                <code>+--------+--------+------------------------+--+</code><br>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><br>
                the first slice (just above) has been defined smaller using the
                -S option<br>
                <br>
              </div>
              <div style="text-align: justify; margin-left: 80px;"><code>+--------+-----------------------------------------------------------------+--+</code><br>
                <code>| slice&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  file data +
                  EA&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp; |Tr|</code><br>
                <code>| header
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |</code><br>
                <code>+--------+-----------------------------------------------------------------+--+</code><br>
              </div>
              <div style="text-align: justify; margin-left: 40px;"><code></code><br>
                <code></code></div>
              <div style="text-align: justify; margin-left: 80px;"><code>+--------+-----------------------------------------------------------------+--+</code><br>
                <code>| slice&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  file data +
                  EA&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp; |Tr|</code><br>
                <code>| header
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp; |&nbsp; |</code><br>
                <code>+--------+-----------------------------------------------------------------+--+</code><br>
                <code></code><br>
                <code>+--------+---------------------+-----------+------
                  +---------+--------+--+</code><br>
                <code>| slice&nbsp; |&nbsp;&nbsp; file data +
                  EA&nbsp;&nbsp;&nbsp; | catalogue | term 1| version | term 2
                  |Tr|</code><br>
                <code>| header
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  | trailer |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;
                  |</code><br>
                <code>+--------+---------------------+-----------+-------+---------+--------+--+<br>
                  <br>
                </code></div>
              <div style="text-align: justify; margin-left: 40px;">the last
                slice is smaller because there was not enough data to make it
                full.<br>
                <br>
                The archive is written sequentially this way.<br>
                <br>
              </div>
              <br>
              <h4>Other Levels</h4>
              <div style="text-align: justify; margin-left: 40px;">Things get a
                bit more complicated if we consider compression and encryption.
                The way the problem is addressed in dar's code is a bit like
                networks are designed in computer science, using the notion of <span
                  style="text-decoration: underline;">layers</span>. Here, there
                is a additional constraint, a given layer may or may not be
                present (encryption, compression, slicing for example). So all
                layer must have the same interface for serving the layer above
                them. This interface is defined by the pure virtual class
                "generic_file", which provides generic methods for reading,
                writing, skipping, getting the current offset when writing or
                reading data to a "generic_file". This way the compressor class
                acts like a file which compresses data wrote to it and writes
                compressed data to another "generic_file" below it. The strong
                encryption and scramble classes act the same but in place of
                compressing/uncompressing they encrypt/decrypt the data to/from
                another generic_file object. The slicing we have seen above
                follows the same principle, this is a "sar" object that
                transfers data wrote to it to several fichier [=file] objects.
                Class fichier [=file] also inherit from generic_file class, and
                is a wrapper for the plain file system calls. Some new classes
                have been added with format 8, in particular the escape class,
                which inserts escape sequence mark at requested position, and
                modifies data wrote for it never looks like an escape sequence
                mark. To reduce the level of context switch when reading the
                catalogue (which makes a ton of small read), a cache class is
                also present, it gather small writes made to it into larger
                writes, and pre-reads a large amount of data to answer to the
                many small reads when building the catalogue in memory from the
                archive.<br>
              </div>
              <div style="margin-left: 40px;"><br>
                Here are now all currently possible layers together:<br>
                <br>
              </div>
              <div style="margin-left: 80px;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +----+--+----+-...........+---------+</code><br>
                <code>archive&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |file|EA|file|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |catalogue|</code><br>
                <code>layout&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |data|&nbsp;
                  |data|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +----+--+----+-...........+---------+</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;
                  | &nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
+-----+
                  | +-------+
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  sparse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |spars| | |sparse |
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  | <br>
                  file&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |file | |
                  |file&nbsp;&nbsp; |
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  detection&nbsp;&nbsp; |detec| | |detect.|
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  layer &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; +-----+ | +-------+
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                </code> <code>(optional)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp; &nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V
                  &nbsp; V&nbsp;&nbsp;&nbsp; V &nbsp; &nbsp;&nbsp;
                  V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +-----------------------------------+</code><br>
                <code>compression&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  (compressed)&nbsp;
                  data&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +-----------------------------------+</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |<br>
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V<br>
                </code><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +-----------------------------------+</code><br>
                <code>escape layer&nbsp; |&nbsp;&nbsp; escaped data / escape
                  sequences |<br>
                </code><code>(optional)&nbsp;&nbsp;&nbsp;
                  +-----------------------------------+</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  / First Terminateur</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V</code><br>
                <code>elastic&nbsp; +---+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +----+---+</code><br>
                <code>buffers&nbsp; |EEE|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  | T1 |EEE|</code><br>
                <code>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;
                  +---+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +----+---+</code><br>
                <code>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  Second </code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  Terminator</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +--------------------------------------------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |</code><br>
                <code>cipher&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (encrypted) data /
                  cache if no encryption
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  +--------------------------------------------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  </code><code>+---------+----+</code><br>
                <code>+-------+&nbsp;
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  </code><code>| trailer | T2 |</code><br>
                <code>|
                  header|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  </code><code>+---------+----+<br>
                  +-------+
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;
                  &nbsp;
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<br>
                  &nbsp; &nbsp; | &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; | &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; &nbsp;
                  &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<br>
                </code> <code>&nbsp;&nbsp;&nbsp; V
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
V
                  &nbsp;&nbsp;&nbsp;&nbsp; v<br>
                </code><code>+-----------------------------------------------------------------------------+</code><br>
                <code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
data&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;
                  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <span style="font-family: monospace;">+</span><code>-----------------------------------------------------------------------------+</code><br>
                <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>slice&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>headers |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;|&nbsp; |&nbsp;&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;|&nbsp; +---|------\&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  |&nbsp; |&nbsp;&nbsp;&nbsp; |&nbsp;
                  |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code><br>
                <code>&nbsp;V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; V&nbsp; V&nbsp;
                  V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V&nbsp;&nbsp; V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V&nbsp;&nbsp; V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  V&nbsp; V&nbsp;&nbsp;&nbsp; V&nbsp;
                  V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; V</code><br>
                <code>+---------+&nbsp; +---------+&nbsp; +---------+&nbsp;
                  +---------+&nbsp; +-------+&nbsp; </code><code>+-------+&nbsp;
                  </code><code>+----+</code><br>
                <code>|HH| data |&nbsp; |HH| data |&nbsp; |HH| data |&nbsp; |HH|
                  data |&nbsp; |HH|data|&nbsp; </code><code>|HH|data|&nbsp; </code><code>|HH|
                  |</code><br>
                <code>+---------+&nbsp; +---------+&nbsp; +---------+&nbsp;
                  +---------+&nbsp; +-------+&nbsp; </code><code>+-------+&nbsp;
                  </code><code>+----+</code><br>
                <code>&nbsp; slice 1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice
                  2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice
                  3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice
                  4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice 5</code><br>
                <code></code></div>
              <div style="margin-left: 40px;"><br>
              </div>
              <br>
              <div style="margin-left: 40px;">
                <div style="text-align: justify;">The <span style="text-decoration: underline; font-weight: bold;">elastic
                    buffers</span> are here to prevent plain text attack, where
                  one knows which data is expected at a given place, an trying
                  to guess the cipher comparing the expected data and the
                  encrypted one. As dar generates structured archives, there
                  would have some possibility that one use this attack to crack
                  an archive encryption. To overcome this problem, elastic
                  buffers have been added at the beginning and at the end of
                  encrypted data. This way it is not possible to know where is
                  located a given archive structure within the encrypted data.
                  The elastic buffers are random data that contain at a random
                  place a pattern that tells the overall size of the buffer
                  (which size is randomly chosen during archive creation). The
                  pattern is of the form "&gt;###&lt;" where the hash field
                  (###) contains the elastic buffer size in binary. Small
                  elastic buffer can be "&gt;&lt;" for two bytes or "X" for one
                  byte, but as it is encrypted beside archive data, it is not
                  possible to determine its size for one that does not hold the
                  archive encryption key. Elastic buffer are usually several
                  kilobyte long. Here follows an example of elastic buffer:<br>
                </div>
                <code><br>
                </code>
                <div style="margin-left: 40px;"><code>972037219&gt;20&lt;8172839</code><br>
                  <code><br>
                    <br>
                  </code></div>
              </div>
              <div style="margin-left: 40px; text-align: justify;">For clarity,
                the size field between '&gt;' and '&lt;' has been written in
                decimal instead of binary, as well as the random data inside the
                elastic buffer. The location of the size field '&gt;20&lt;' is
                also randomly chosen at creation time.<span style="text-decoration: underline; font-weight: bold;"><br>
                  <br>
                </span>A <span style="text-decoration: underline; font-weight: bold;">Teminateur</span>
                is short structure that is intended to be read backward. It
                gives the absolute position of a given item within the archive:
                The second terminateur let dar skip at the beginning of the
                archive trailer. The first terminateur (eventually encrypted)
                let dar skip at the beginning of the catalogue).<br>
              </div>
              <div style="margin-left: 40px;"><code></code><br>
              </div>
              <br>
              <br>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><a name="scrambling"></a>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Scrambling</h3>
              <br>
              <div style="text-align: justify;">Before strong encryption was
                implemented, dar had only a very simple and weak encryption
                mechanism. It remains available in current release under the
                "scram" algorithm name. It mains advantage is that is does not
                rely on any external library, it is completely part of libdar.<br>
              </div>
              <br>
              How does it works?<br>
              <br>
              <div style="text-align: justify;">Consider the pass phrase as a
                string, thus a sequence of bytes, thus a sequence of integer
                each one between 0 and 255 (including 0 and 255). The data to
                "scramble" is also a sequence of byte, usually much longer than
                the pass phrase. The principle is to add byte by byte the pass
                phrase to the data, modulo 256. The pass phrase is repeated all
                along the archive. Let's take an example: <br>
              </div>
              <br>
              the pass phrase is "he\220lo" (where \220 is the character which
              decimal value is 220). the data is "example"<br>
              <br>
              taken from ASCII standard:<br>
              <div style="margin-left: 40px;">h = 104<br>
                l = 108<br>
                o = 111<br>
                e = 101<br>
                x = 120<br>
                a = 97<br>
                m = 109<br>
                p = 112<br>
              </div>
              <br>
              &nbsp;<code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                x&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                a&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                m&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                p&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                l&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; e<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                101&nbsp;&nbsp;&nbsp;&nbsp; 120&nbsp;&nbsp;&nbsp;&nbsp;
                97&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 109&nbsp;&nbsp;&nbsp;&nbsp;
                112&nbsp;&nbsp;&nbsp;&nbsp; 108&nbsp;&nbsp;&nbsp;&nbsp; 101<br>
                <br>
                +&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                h&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \220&nbsp;&nbsp;&nbsp;
                l&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                o&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                h&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; e<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                104&nbsp;&nbsp;&nbsp;&nbsp; 101&nbsp;&nbsp;&nbsp;&nbsp;
                220&nbsp;&nbsp;&nbsp;&nbsp; 108&nbsp;&nbsp;&nbsp;&nbsp;
                111&nbsp;&nbsp;&nbsp;&nbsp; 104&nbsp;&nbsp;&nbsp;&nbsp; 101<br>
                <br>
                ---------------------------------------------------------------<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                205&nbsp;&nbsp;&nbsp;&nbsp; 221&nbsp;&nbsp;&nbsp;&nbsp;
                317&nbsp;&nbsp;&nbsp;&nbsp; 217&nbsp;&nbsp;&nbsp;&nbsp;
                223&nbsp;&nbsp;&nbsp;&nbsp; 212&nbsp;&nbsp;&nbsp;&nbsp; 202<br>
                <br>
                ---------------------------------------------------------------<br>
                modulo<br>
                256 :&nbsp;&nbsp; 205&nbsp;&nbsp;&nbsp;&nbsp;
                221&nbsp;&nbsp;&nbsp;&nbsp; 61&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                217&nbsp;&nbsp;&nbsp;&nbsp; 223&nbsp;&nbsp;&nbsp;&nbsp;
                212&nbsp;&nbsp;&nbsp;&nbsp; 202<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                \205&nbsp;&nbsp;&nbsp; \201&nbsp;&nbsp;&nbsp;
                =&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \217&nbsp;&nbsp;&nbsp;
                \223&nbsp;&nbsp;&nbsp; \212&nbsp;&nbsp;&nbsp; \202</code><br>
              <br>
              thus the data "example" will be written in the archive
              "\205\201=\217\223\212\202"<br>
              <br>
              <div style="text-align: justify;">This method allows to decode any
                portion without knowing the rest of the data. It does not
                consume much resources to compute, but it is terribly weak and
                easy to crack. Of course, the data is more difficult to retrieve
                without the key when the key is long. Today dar can also use
                strong encryption (blowfish and few others) and thanks to a
                encryption block can still avoid reading the whole archive to
                restore any single file.</div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><br>
      <table style="text-align: left; width: 90%;" cellspacing="2" cellpadding="2"
        border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Asymmetrical Encryption and Signature<br>
              </h3>
              <br>
              <div style="text-align: justify;">dar relies on gpgme library (GPG
                made Easy) to provide strong asymmetrical encryption and
                signature of an archive. Asymmetrical encryption is what you do
                when you use a public key to cypher data (=encrypt data) and a
                private key to uncypher it (=decrypt it). However, <span style="font-weight: bold;">dar
                  does <span style="text-decoration: underline;">not </span>encrypt
                  <span style="text-decoration: underline;">the whole archive</span>
                  that way</span>, not it signs it that way, neither.<br>
                <br>
                Instead, dar relies on the symmetrical strong encryption
                algorithm it is aware of for some time (blowfish, twofish,
                camellia, aes, etc.) to cipher the archive. The key used to
                cipher the archive is chosen randomly, encrypted and eventually
                signed using the provided recipient email of the user keyring.
                This encrypted key is then put in the archive header and
                trailer.<br>
                <br>
                Well, to be more precise about the symmetrical key that is
                encrypted in the archive: its length user defined and defaults
                to 512 bytes (4096 bits). A random variation of +0 to +255 bytes
                is added by libdar to this size. Then the key value itself is
                chosen randomly. The random generator used here is the one
                provided by libgcrypt using the GCRY_STRONG_RANDOM entropy
                level.<br>
                <br>
                Why doing that way and not using the asymmetrical algorithm to
                cypher the whole archive? <br>
                <ul>
                  <li>Because it would no more be possible to extract a single
                    file from the archive or to read the archive's contents
                    whithout reading the whole archive.</li>
                  <li>Because it would not be possible the quickly verify
                    archive signatures (well, see below)<br>
                  </li>
                  <li>Because it would avoid recovering an corrupted archive
                    after the point of corruption</li>
                  <li>Because it would cost much disk space to encrypt an
                    archive for it be readable by more than one recipients<br>
                  </li>
                </ul>
                Yes, you can provide several recipients from your GPG keyring
                giving their email addresses and also at the same time sign the
                archive with one of your private key. The resulting archive will
                be possible to decrypt only by those recipients. And anyone
                knowing your public key will be able to verify that the archive
                has been generated by you. Of course the verification only
                validates the encryption key is from an archive you have
                personnaly generated, a man in the middle could modify the
                archive data located after the key in the archive, however it
                would not be possible to uncipher the tampered data using the
                signed key, or it would mean that the man in the middle could
                generate encrypted data using the same symmetric key that is
                encrypted in the archive. This might be the possible if a
                recipient's private key has been compromised. Thus the signature
                of the key is not sufficient to prove the authenticity of the
                whole archive. To cope with that risks, a better solution is to
                activate the slice hashing (md5 or sha1) and to sign these small
                files to be provided beside the archive slices.<br>
                <br>
              </div>
            </td>
          </tr>
        </tbody>
      </table>
      <hr style="width: 100%; height: 2px;"><a name="overflow"></a><br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Overflow in arithmetic integer operations</h3>
              <br>
              <div style="text-align: justify;">Some code explanation about the
                detection of integer arithmetic operation overflows. We speak
                about *unsigned* integers, and we have only portable standard
                ways to detect overflows when using 32 bits or 64 bits integer
                in place of infinint.<br>
                <br>
                Developed in binary, a number is a finite suite of digits (0 or
                1). To obtain the original number from the binary
                representation, we must multiply each digit by a power of two.
                example the binary representation "101101" designs the number N
                where:<br>
                <br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">N = 2^5 + 2^3
                + 2^2 + 2^0<br>
              </div>
              <div style="text-align: justify;"><br>
                in that context we will say that 5 is the maximum power of N
                (the power of the higher non null binary digit).<br>
                <br>
              </div>
              for the addition "+" operation, if an overflow occurs, the result
              is less than one or both operands, so overflow is not difficult to
              detect. To convince you, let's assume that the result is greater
              both operands while it has overflowed. Thus the real result
              (without overflow) less the first operands should gives the second
              argument, but here we get a value that is greater than the all 1
              bits integer (because there was an overflow and the resulting
              overflowed value is greater than the first second and the first
              operand), so this is absurd, and in case of overflow the resulting
              value is less than one of the operands.<br>
              <div style="text-align: justify;"><br>
                for substraction "-" operation, if the second operand is greater
                than the first there will be an overflow (result must be
                unsigned thus positive) else there will not be any overflow.
                Thus detection is even more simple.<br>
                <br>
                for division "/" and modulo "%" operations, there is never an
                overflow (there is just illicit the division by zero).<br>
                <br>
                for multiplication "*" operation, a heuristic has been chosen to
                quickly detect overflow, the drawback is that it may triggers
                false overflow when number get near the maximum possible integer
                value. Here is the heuristic used:<br>
                <br>
                given A and B two integers, which max powers are m and n
                respectively, we have<br>
                <br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">A &lt;
                2^(m+1)<br>
              </div>
              <div style="text-align: justify;">and<br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">B &lt;
                2^(n+1)<br>
              </div>
              <div style="text-align: justify;"><br>
                thus we also have:<br>
                <br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">A.B &lt;
                2^(m+1).2^(n+1)<br>
              </div>
              <div style="text-align: justify;"><br>
                which is:<br>
                <br>
              </div>
              <div style="margin-left: 40px; text-align: justify;">A.B &lt;
                2^(m+n+2)<br>
              </div>
              <div style="text-align: justify;"><br>
              </div>
              by consequences we know that the maximum power of the product of A
              by B is at most m+n+1 and while m+n+1 is less than or equal to the
              maximum power of the integer field there will not be overflow else
              we consider there will be an overflow even if it may not be always
              the case (this is an heuristic algorithm). </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><a name="strong_encryption"></a><br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Strong encryption</h3>
              <br>
              <div style="text-align: justify;">Several cyphers are available.
                Remind that "scrambling" is not a strong encryption cypher, all
                other are.<br>
                <br>
                to be able to use a strong encrypted archive you need to know
                the three parameters used at creation time:<br>
              </div>
              <ul style="text-align: justify;">
                <li>the cypher used (blowfish, ...)</li>
                <li>the key or password used</li>
                <li>the encryption block size used</li>
              </ul>
              <div style="text-align: justify;">no information about these
                parameters is stored in the generated archive. If you make an
                error on just one of them, you will not be able to use your
                archive. If you forgot one of them, nobody can help you, you can
                just consider the data in this archive as lost. This is the
                drawback of strong encryption. <br>
                <br>
              </div>
              <h4 style="text-align: justify;">How is it implemented?</h4>
              <div style="text-align: justify;">To not completely break the
                possibility to directly access file, the archive is&nbsp; not
                encrypted as a whole (as would do an external program). The
                encryption is done block of data by block of data. Each block
                can be decrypted, and if you want to read some data somewhere
                you need to decrypt the whole block(s) it is in.<br>
                <br>
                In consequence, the larger the block size is, the stronger the
                encryption is. But also the larger the block size is, the longer
                it will take to recover a given file, in particular when the
                file size to restore is much smaller than the encryption block
                size used.<br>
                <br>
                An encryption block size can range from 10 bytes to 4 GB.<br>
                <br>
                If encryption is used as well as compression, compression is
                done first, then encryption is done on compressed data.<br>
                <br>
                An "elastic buffer" is introduced at the beginning and at the
                end of the archive, to protect against plain text attack.&nbsp;
                The elastic buffer size randomly varies and is defined at
                execution time. It is composed of random (srand()) values. Two
                marks characters '&gt;' and '&lt;' delimit the size field, which
                indicate the byte size of the elastic buffer. The size field is
                randomly placed in the buffer. Last, the buffer is encrypted
                with the rest of the data. Typical elastic buffer size range
                from 1 byte to 10 kB, for both initial and terminal elastic
                buffers. <br>
                <br>
                Elastic buffers are also used inside encryption blocks. The
                underlying cypher may not be able to encrypt at the requested
                block size boundary. If necessary a small elastic buffer is
                appended to the data before encryption, to be able, at
                restoration time, to know the amount of data and the amount of
                noise around it.<br>
                <br>
                Let's take an example with blowfish. Blowfish encrypts by
                multiple of 8 bytes (blowfish chain block cypher). An elastic
                buffer is always added to the data of a encryption block, its
                minimal size is 1 byte. <br>
                <br>
                Thus, if you request a encryption block of 3 bytes, these 3
                bytes will be padded by an elastic buffer of 5 bytes for these 8
                bytes to be encrypted. This will make a very poor compression
                ratio as only 3 bytes on 8 bytes are significant.<br>
                <br>
                If you request a encryption block of 8 bytes, as there is no
                room for the minimal elastic buffer of 1 byte, a second 8 byte
                block is used to put the elastic buffer, so the real encryption
                block will be 16 bytes.<br>
                <br>
                Ideally, a encryption block of 7 bytes, will use 8 bytes with 1
                byte for the elastic buffer.<br>
                <br>
                This problem tends to disappear when the encryption block size
                grows, so this should not be a problem in normal conditions.
                Encryption block of 3 bytes is not a good idea to have a strong
                encryption scheme, for information, the default encryption block
                size is 10kB and is user settable to larger values.<br>
                <br>
                <h4>Key Derivation Fonction - KDF<br>
                </h4>
                strong encryption uses secret key, to cipher/uncipher data, we
                will say "password" to simplify in the following. <br>
                <br>
                But directly using a human provided password would provide a
                weak encryption. To overcome this weakness, the state of the art
                is to use a key derivation function, which takes in input the
                human provided password plus a "salt" and outputs a stronger key
                (salt is described below). This function is based on a hash
                algoritm (sha1 by default, but this value can be modified since
                archive format 10/release 2.6.0) and an iteration count (2000
                before format 10, 200000 since release 2.6.0 by default and this
                can be changed), it will mix salt and passphrase then hash the
                result the number of iteration count that is defined, taking as
                hash input the previous hash output at each cycle.<br>
                <br>
                The <span style="font-weight: bold;">salt</span> is a randomly
                chosen value by libdar that is stored in clear in the archive
                header, beside the iteration count and hash algorithm used for
                the KDF. Thus even if the user has the same password for
                different archive, the effective key used for strong encryption
                will differ from archive to archive, making much more difficult
                for an attacker to crack an archive using statiscical methods
                over a large number of archives sharing the same human provided
                password, as the effective encryption key used differs from
                archive to archive thanks to the salt. Even knowing the salt
                (which is available in clear for each archive) the attacker
                should have to use the KDF function for each archive, times each
                password to test in order to leverage the fact several archives
                have been encrypted with the same password. In today computer
                200,000 iteration of sha1 takes almost one second, this is quite
                unoticeable by the real user, but for an attacker wanting to try
                100,000 passwords over 8 archives sharing the same human
                passwords, this would cost 800,000 seconds (around 10 days) just
                be in order to start cracking user archives...<br>
                <br>
                As seen above, an archive is encrypted block by block.
                Independently of a salt per archive, a second level of salt per
                encryption block is used inside a give archive, salt which is
                derived from the block number, <a href="#sym">more details
                  below</a><br>
                <br>
              </div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><a name="thread_safe"></a><br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>libdar and thread-safe requirement</h3>
              <br>
              <div style="text-align: justify;">This is for those who plane to
                use libdar in their own programs.<br>
                <br>
                If you plan to have only one thread using libdar there is no
                problem, of course, you will however have to call one of the
                get_version() first, as usual. Thing change if you intend to
                have several concurrent threads using libdar library.<br>
                <br>
                libdar is thread-safe under certain conditions:<br>
                <br>
                Several 'configure' options have an impact on thread-safe
                support:<br>
                <br>
                --enable-test-memory is a debug option that avoid libdar to be
                thread-safe,&nbsp; so don't use it.<br>
                --enable-special-alloc (now disable by default since version
                2.5.5), makes a thread-safe library only if POSIX mutex are
                available (pthread_mutex_t type).<br>
                --disable-thread-safe avoid looking for mutex, so unless
                --disable-special-alloc is also used, the generated library will
                not be thread safe.<br>
                <br>
                You can check the thread safe capability of a library thanks to
                the get_compile_time_feature(...) call from the API. Or use 'dar
                -V' command, to&nbsp; quickly have the corresponding values and
                check using 'ldd' to see which library has been dynamically
                linked to dar, if applicable.<br>
                <br style="font-weight: bold; text-decoration: underline;">
                <span style="font-weight: bold; text-decoration: underline;">IMPORTANT:</span><br>
                As more as before it is mandatory to call get_version() call
                before any other call, when the call returns, libdar is ready
                for thread safe. Note that even if the prototype does not change
                get_version() *may* now throw an exception, so use
                get_version_noexcept() if you don't want to manage exceptions.<br>
                <br>
                For more information about libdar and its API, check the <a href="api_tutorial.html">doc/api_tutorial.html</a>
                document and the API reference manual under <a href="man/index.html">doc/html/index.html</a><br>
                <br>
              </div>
            </td>
          </tr>
        </tbody>
      </table>
      <hr style="width: 100%; height: 2px;"><a name="dar_manager_deleted"></a>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Dar_manager and delete files</h3>
              <br>
              <div style="text-align: justify;">This is for further reference
                and explanations.<br>
                <br>
                In dar archive when a file has been deleted since the backup of
                reference (in case of differential archive), an entry of a
                special type (called "detruit") is put in the catalogue of the
                archive which only contains the name of the missing file. <br>
                <br>
                In a dar_manager database, to each files that have been found in
                one of the archive used to build this database corresponds a
                list of association. These associations put in relation the
                mtime (date of modification of the file) to the archive number
                where the file has been found in that state. <br>
                <br>
                There is thus no way to record "detruit" entries in a
                dar_manager database, as no date is associated with this type of
                object. Yes, in a dar archive, we can only notice a file has
                been destroyed because it is not present in the filesystem but
                is present in the catalogue of the archive of reference. Thus we
                know the file has been destroyed between the date the archive of
                reference has been done and the date the current archive is
                actually done. Unfortunately, no date is recorded in dar
                archives telling it has been done at which time.<br>
                <br>
                Thus, from dar_manager, inspecting a catalogue, there is no way
                to give a significant date to a "detruit" entry. In
                consequences, for a given file which has been removed, then
                recreated, then removed again along a series of differential
                backups, it is not possible to order the times when this file
                has been removed in the series of date when it has existed. <br>
                <br>
                The ultimate consequence is that if the user asks dar_manager to
                restore a directory in the state just before a given date (-w
                option), it will not be possible to know if that file existed at
                that time. We can effectively see that it was not present in a
                given archive but as we don't know the date of that archive we
                cannot determine if it is before of after the date requested by
                the user, and dar_manager is not able to restore the non
                existence of a file for a given time, we must use dar directly
                with the archive that has been done at the date we wish. <br>
                <br>
                Note that having a date stored in each dar archive would not
                solve the problem without some more informations. First, we
                should assume that the date is consistent from host to host and
                from time to time (What if the user change of time due to
                daylight saving or move around the Earth, or if two users in two
                different places share a filesystem --- with rsync, nfs, or
                other mean --- and do backups alternatively...). Let's assume
                the system time is significant and thus let's imagine what would
                be the matter if in each archive this date of archive
                construction was stored. <br>
                <br>
                Then when a detruit object is met in an archive it can be given
                the date the archive has been built and thus ordered in the
                series of dates when the corresponding file was found in other
                archives. So when the user asks for restoration of a directory a
                given file's state is possible to know, and thus the restoration
                of the corresponding archive will do what we expect : either
                remove the file (if the selected backup contains an&nbsp;
                "detruit" object, or&nbsp; restore the file in the state it
                had).<br>
                <br>
                Suppose now, a dar_manager database built with a series of full
                backup. There will thus no be any "detruit" objects, but a file
                may be present or may be missing in a given archive. The
                solution is thus that once an archive has been integrated in the
                database, the last step is to scan the whole database for files
                that have no date associated with this last archive, thus we can
                assume these files were not present and add the date of the
                archive creation with the information that this file was removed
                at that time. Moreover, if the last archive add a file which was
                not know in archives already present in the database, we must
                consider this file was deleted in each of these previous
                archives, but then we must record the dates of creation for all
                these previous archive to be able to put this information
                properly in the database. But, in that case we would not be able
                to make dar removing a file, as no "detruit" object exist (all
                archive are full backups), and dar_manager should remove itself
                the entry from the filesystem. Beside the fact that it is not
                the role to dar_manager to directly interact with the
                filesystem, dar_manager should record an additional information
                to know if a file is deleted because it has been found a
                "detruit" object in an archive, or if it is deleted because it
                has not been found any entry in an given archive. This is
                necessary to known whether to rely on dar to remove the file or
                to make dar_manager do it itself, or maybe better is to never
                rely on dar to remove a file but always let dar_manager do it
                itself. <br>
                <br>
                Assuming we accept to make dar_manager able to rm entries from
                filesystem without relying on dar, we must store the date of the
                archive creation in each archive, and store these dates for each
                archive in dar_manager databases. Then instead of using the
                mtime of each file, we could do something much more simple in
                database: for each file, record if it was present or not in each
                archive used to built the database, and beside this, store only
                the archive creation date of each archive. This way, dar_manager
                would only have for each file to take the last state of the file
                (deleted or present) before the given date (or the last known
                state if no date is given) and either restore the file from the
                corresponding archive or remove it.<br>
                <br>
                But if a user has removed a file by accident and only notice
                this mistake after several backups, it would become painful to
                restore this file, as the user should find manually at which
                date it was present to be able to feed dar_manager with the
                proper -w option, this worse than looking for the last archive
                that has the file we look for.<br>
                <br>
                Here we are back to the restoration of a file and the
                restoration of a state. By state, I mean the state a directory
                tree had at a given time, like a photo. In its original version
                dar_manager was aimed to restore files, whatever they exist or
                not in the last archive added to a database. It only finds the
                last archive where the file is present. Making dar_manager
                restore a state, and thus considering files that have been
                removed at a given date, is no more no less than restoring from
                a given archive, directly with dar. So all this discussion about
                the fact that dar_manager is not able to handle files that have
                been removed, to arrive to the fact that adding this feature to
                dar_manager will make it become quite useless... sight. But,
                that was necessary. </div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><a name="NLS"></a><br>
      <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
        cellspacing="2" cellpadding="2" border="0">
        <tbody>
          <tr>
            <td style="vertical-align: top;">
              <h3>Native Language Support / gettext / libintl</h3>
              <br>
              <div style="text-align: justify;">Native Language Support (NLS) is
                the fact a given program can display its messages in different
                languages. For dar, this is implemented using the gettext tools.
                This tool must be installed on the system for dar can be able to
                display messages in another language than English.&nbsp; <br>
                <br>
                Things are the following:<br>
                - On a system without gettext dar will not use gettext at all.
                All messages will be in English (OK maybe better saying
                Frenglish) ;-)<br>
                - On a system with gettext dar will use the system's gettext,
                unless you use --disable-nls option with the configure script.<br>
                <br>
                If NLS is available you just have to set the LANG environment
                variable to your locale settings to change the language in which
                dar displays its messages (see ABOUT-NLS for more about the LANG
                variable).<br>
                <br>
                just for information, gettext() is the name of the call that
                makes translations of string in the program. This call is
                implemented in the library called 'libintl' (intl for
                Internationalization). Last point, gettext by translating
                strings, makes the Native Language Support (NLS) possible, in
                other words, it let you have the messages of your
                preferred&nbsp; programs being displayed in you native language
                for those not having the English as mother tong. <br>
                <br>
                This was necessary to say, because you may miss the links
                between "gettext" , "libintl" and "NLS".<br>
                <br>
                READ the ABOUT-NLS file at the root of the source package to
                learn more about the way to display dar's messages in your own
                language. Note that not all languages are yet supported, this is
                up to you to send me a translation in your language and/or
                contact a translating team as explained in ABOUT-NLS.<br>
                <br>
                To know which languages are supported by dar, read the
                po/LINGUAS file and check out for the presence of the
                corresponding *.po files in this directory. </div>
            </td>
          </tr>
        </tbody>
      </table>
      <br>
      <hr style="width: 100%; height: 2px;"><br>
    </center>
    <table style="width: 90%; margin-right: auto; margin-left: auto; text-align: left;"
      cellspacing="2" cellpadding="2" border="0">
      <tbody>
        <tr>
          <td style="vertical-align: top;">
            <h3><span style="font-weight: bold;"><a name="Dar_relase_Process_in_brief"></a>Dar
                Release Process<br>
              </span></h3>
            <div style="text-align: justify;"><span style="font-weight: bold;"></span><span
                style="text-decoration: underline;">Development Phase:</span><br>
              Dar receive new features during the development phase, at this
              stage sources are modified and tested after each feature addition.
              The development sources are stored in a <a href="http://sourceforge.net/p/dar/code/">GIT
                repository</a> at sourceforge, repository you can access in
              read-only. <br>
              <br>
              <span style="text-decoration: underline;">Frozen API Phase:</span><br>
              No new feature that would change the API are added. The API shall
              be documented enough to let API users give their feedback about
              the design and its implementation. During this time, development
              continues, whatever is necessary while it does not changes the
              API, like documentation of the whole project, problem fix in
              libdar, new features in command-line part of the source, and so
              on.<br>
              <br>
              <span style="text-decoration: underline;">Pre-release Phase:</span><br>
              Once the documentation and API is stable, comes the pre-release
              phase, this phase starts and ends by a email to the dar-news
              mailing-list. At this period intensive test is done on the
              pre-release source, feedback and information about <a href="http://dar.linux.free.fr/pre-release">new
pre-release
                packages</a> are exchanged through the <a href="http://lists.sourceforge.net/lists/listinfo/dar-pre-release">pre-release
                mailing-list</a>, this mailing-list lives only during the
              pre-release phases and is not archived, nor visible through a mail
              to news gateway. Of&nbsp; course, you are welcome to participate
              in the testing process and report to the pre-release mailing list
              any problem you could meet with a given pre-release package.<br>
              <br>
              <span style="text-decoration: underline;">Release Phase:</span><br>
              Some little time after pre-release has ended, a first package is
              released (last number version is zero) and <a href="http://sourceforge.net/project/showfiles.php?group_id=65612">available
at
                sourceforge</a> for download. This phase also begins by an email
              to dar-news mailing-list. During that phase, users may report
              bugs/problem about the released software,&nbsp; depending on the
              amount of bugs found and of their importance a new release will
              take place to only fixe these found bugs (no features is added),
              the last number of the version is incremented by one and a new
              mail to dar-news is sent with the list of problem fixed by the new
              release. The release phase ends when a new release phase begins,
              thus during a release phase a concurrent development phase takes
              place, then a frozen API, then a pre-release phase but for a new
              major version (the first or the second number of the version
              changes).<br>
            </div>
            <span style="font-weight: bold;"><br>
            </span>
            <h3><span style="font-weight: bold;"><a name="Dar_version_naming"></a>Dar's
                Versions<br>
              </span></h3>
            <span style="font-weight: bold;"></span>
            <h4>package release version</h4>
            <div style="text-align: justify;">Dar packages are release during
              the pre-release phase (<a href="#Dar_relase_Process_in_brief">see
                above</a>). Each version is identified by three number separated
              by dot like for example, version 2.3.0 . The last number is
              incremented between releases that take place in the same release
              phase (just bug have been fixed), the middle number increments at
              each pre-release phase. Last the first number is incremented when
              a major change in the software structure took place [version 2.0.0
              has seen the split of dar's code in one part related to
              command-line and the rest put in a library called libdar, that can
              be accessed by a well defined API even by external softwares (like
              <a href="http://kdar.sourceforge.net/">kdar</a> for example).
              Version 2.0.0 has also seen the apparition of the configure script
              and the use of the gnu tools autoconf, autmake, libtool and
              gettext, thus in particular the possibility to have
              internationalization]. <br>
              <br>
              Note that release versionning is completely different from what is
              done for the Linux kernel, here for dar all versionnized packages
              are stable released software and thus stability increases with the
              last number of the version.<br>
              <br>
            </div>
            <h4>Libdar version</h4>
            <div style="text-align: justify;">Unfortunately, the release version
              does not give much information about the compatibility of
              different libdar version, from the point of view of an external
              application, that thus has not been released with libdar and may
              be faced to different libdar versions. So, libdar has its own
              version. It is also a three number version, (for example, current
              libdar version is version 3.1.2), but each number has a different
              meaning. The last number increases with a new version that only
              fixes bugs, the middle number increases with when new features has
              been added but stay compatible with older libdar version in the
              way to use older features. Last the first number changes when the
              API has been changed in a way that no ascendant compatibility is
              no more possible for some features.<br>
              <br>
            </div>
            <h4>Other versions</h4>
            <div style="text-align: justify;"><br>
              beside the libdar library, you can find five command-line
              applications: dar, dar_xform, dar_slave, dar_manager and dar_cp.
              These except dar have their own version which is here too made of
              three numbers. Their meaning is the same as the meaning for the
              package release version: The last number increases upon bug fix,
              the middle upon new feature, the first upon major architecture
              changes.<br>
              <br>
              <h4>Archive format version</h4>
              When new features come, it is sometime necessary to change the
              structure of the archive. To be able to know the format used in
              the archive, a field is present in each archive that defines this
              format. Each dar binary can thus read all archive format, well of
              course a particular version cannot guess the format of archive
              that have been defined *after* that dar binary version has been
              released. If you try to open a recent archive with an old dar
              binary, you will have a warning about the fact that dar is
              probably not able to read the archive, dar will then ask you if
              you want to proceed anyway. Of course, you can try to read it, but
              this is at your own risk. In particular, depending on the feature
              used (See the Changelog to know which feature required to upgrade
              the archive format), you may succeed reading a recent archive with
              an old dar binary and get neither error nor warning, but this does
              not mean that dar did all that was necessary to restore the files
              properly, so it is advised to avoid using an archive with a
              version of dar that is tool old to handle the archive format
              properly (and rather reserve this possibility only in case of
              necessity).<br>
            </div>
            <h4>Cross reference matrix</h4>
            <div style="text-align: justify;">OK, you may now find that this is
              a bit complex so a list of version is give below. Just remember
              that there are two points of view: The command-line user and the
              external application developer.<br>
            </div>
            <span style="font-weight: bold;"></span></td>
        </tr>
      </tbody>
    </table>
    <br>
    <table style="width: 90%; text-align: left; margin-left: auto; margin-right: auto;"
      cellspacing="2" cellpadding="2" border="1">
      <tbody>
        <tr>
          <td style="vertical-align: top; width: 15%; font-weight: bold; text-align: center;">Date<br>
          </td>
          <td style="vertical-align: top; width: 10%; text-align: center; font-weight: bold;">release
            (and<br>
            dar version)<br>
          </td>
          <td style="vertical-align: top; text-align: center; width: 10px;"><span
              style="font-weight: bold;">Archive format</span><br>
          </td>
          <td style="vertical-align: top; text-align: center; width: 10px;"><span
              style="font-weight: bold;">Database</span><br style="font-weight: bold;">
            <span style="font-weight: bold;">Format</span><br>
          </td>
          <td style="vertical-align: top; width: 10%; font-weight: bold; text-align: center;">libdar
            version<br>
          </td>
          <td style="vertical-align: top; width: 10%; font-weight: bold; text-align: center;">dar_xform<br>
          </td>
          <td style="vertical-align: top; width: 10%; font-weight: bold; text-align: center;">dar_slave<br>
          </td>
          <td style="vertical-align: top; width: 10%; font-weight: bold; text-align: center;">dar_manager<br>
          </td>
          <td style="vertical-align: top; width: 10%; font-weight: bold; text-align: center;">dar_cp<br>
          </td>
          <td style="vertical-align: top; font-weight: bold; width: 10%; text-align: center;">dar_split</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 2nd, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 24th, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 8th, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 27th, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 26th, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">02<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Nov. 4th, 2002<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Jan. 10th, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">1.1.0</td>
          <td style="vertical-align: top; text-align: center;">1.1.0</td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 19th, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Nov. 2nd, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Nov. 21th, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Dec. 7th, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Dec. 14th, 2003<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.0.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Jan. 3rd, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.0.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 8th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">March 5th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">March 12th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 6th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">July 13th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Sept. 12th, 2004<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Jan. 29th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.1.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">2.0.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Jan. 30th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 20th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 12th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Sept. 13th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Nov. 5th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.1.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Dec. 6th, 2005<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.1.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Jan. 19th, 2006<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.1.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 24th, 2006<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.2.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">3.1.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 24th, 2006<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">05<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.0.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 26th, 2006<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">05<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.0.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Oct. 30th, 2006<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">05<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.0.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0</td>
          <td style="vertical-align: top; text-align: center;">1.3.2</td>
          <td style="vertical-align: top; text-align: center;">1.4.0</td>
          <td style="vertical-align: top; text-align: center;">1.1.0</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 24th, 2007<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">05<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 30th, 2007<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">06<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Aug. 28th, 2007<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">06<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Sept. 29th, 2007<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">06<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Feb. 10th, 2008<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">06<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top;">
            <div style="text-align: right;">June 20th, 2008<br>
            </div>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">07<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">May 22nd, 2009<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">07<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 9th, 2010<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">07<br>
          </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.3.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top;">
            <div style="text-align: right;">March 13th, 2011<br>
            </div>
          </td>
          <td style="vertical-align: top; text-align: center;">2.3.11 </td>
          <td style="vertical-align: top; text-align: center;">07 </td>
          <td style="vertical-align: top; text-align: center;">01 </td>
          <td style="vertical-align: top; text-align: center;">4.5.0 </td>
          <td style="vertical-align: top; text-align: center;">1.4.3 </td>
          <td style="vertical-align: top; text-align: center;">1.3.4 </td>
          <td style="vertical-align: top; text-align: center;">1.4.3 </td>
          <td style="vertical-align: top; text-align: center;">1.2.2 </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">February 25th,
            2012</td>
          <td style="vertical-align: top; text-align: center;">2.3.12</td>
          <td style="vertical-align: top; text-align: center;">07</td>
          <td style="vertical-align: top; text-align: center;">01<br>
          </td>
          <td style="vertical-align: top; text-align: center;">4.5.1</td>
          <td style="vertical-align: top; text-align: center;">1.4.3</td>
          <td style="vertical-align: top; text-align: center;">1.3.4</td>
          <td style="vertical-align: top; text-align: center;">1.4.3</td>
          <td style="vertical-align: top; text-align: center;">1.2.2</td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 2nd, 2011<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.0</td>
          <td style="vertical-align: top; text-align: center;">08</td>
          <td style="vertical-align: top; text-align: center;">02</td>
          <td style="vertical-align: top; text-align: center;">5.0.0</td>
          <td style="vertical-align: top; text-align: center;">1.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">July 21st, 2011<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">02</td>
          <td style="vertical-align: top; text-align: center;">5.1.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.6.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Sept. 5th, 2011<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">02</td>
          <td style="vertical-align: top; text-align: center;">5.1.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.6.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">February 25th,
            2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.2.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.0</td>
          <td style="vertical-align: top; text-align: center;">1.4.0</td>
          <td style="vertical-align: top; text-align: center;">1.7.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">March 17th, 2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.2.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 15th, 2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.2.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 24th, 2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.2.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">July 5th, 2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.2.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">September 9th,
            2012<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.3.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 6th, 2013<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.3.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">March 9th, 2013<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.3.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">Aug. 26th, 2013<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.4.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 19th, 2014<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.12<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.5.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 21st, 2014<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 15th, 2014<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.14<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">September 6th,
            2014<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.15<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 18th, 2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.16<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 31th, 2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.17<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;"><br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">August 30th, 2015
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.18 </td>
          <td style="vertical-align: top; text-align: center;">08.1 </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.5 </td>
          <td style="vertical-align: top; text-align: center;">1.5.6 </td>
          <td style="vertical-align: top; text-align: center;">1.4.6 </td>
          <td style="vertical-align: top; text-align: center;">1.7.8</td>
          <td style="vertical-align: top; text-align: center;">1.2.8 </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 4th, 2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.19<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03</td>
          <td style="vertical-align: top; text-align: center;">5.6.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">November 21th,
            2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.20<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.6.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">----- </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 24th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.21<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03 </td>
          <td style="vertical-align: top; text-align: center;">5.6.8 </td>
          <td style="vertical-align: top; text-align: center;">1.5.9 </td>
          <td style="vertical-align: top; text-align: center;">1.4.9 </td>
          <td style="vertical-align: top; text-align: center;">1.7.11 </td>
          <td style="text-align: center;">1.2.10</td>
          <td style="text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 5th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.22<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03 </td>
          <td style="vertical-align: top; text-align: center;">5.6.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 29th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.23<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03 </td>
          <td style="vertical-align: top; text-align: center;">5.6.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 21st, 2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.4.24<br>
          </td>
          <td style="vertical-align: top; text-align: center;">08.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">03 </td>
          <td style="vertical-align: top; text-align: center;">5.6.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="text-align: center;">-----</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 4th, 2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.0</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.7.0</td>
          <td style="vertical-align: top; text-align: center;">1.5.7</td>
          <td style="vertical-align: top; text-align: center;">1.4.7</td>
          <td style="vertical-align: top; text-align: center;">1.7.9</td>
          <td style="vertical-align: top; text-align: center;">1.2.9</td>
          <td style="vertical-align: top; text-align: center;">1.0.0</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 17th, 2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.1</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.7.1</td>
          <td style="vertical-align: top; text-align: center;">1.5.8</td>
          <td style="vertical-align: top; text-align: center;">1.4.8</td>
          <td style="vertical-align: top; text-align: center;">1.7.10</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.0.0</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">November 21st,
            2015<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.7.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 4th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.7.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 24th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09 </td>
          <td style="vertical-align: top; text-align: center;">04 </td>
          <td style="vertical-align: top; text-align: center;">5.8.0 </td>
          <td style="vertical-align: top; text-align: center;">1.5.9 </td>
          <td style="vertical-align: top; text-align: center;">1.4.9 </td>
          <td style="vertical-align: top; text-align: center;">1.7.11 </td>
          <td style="text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 5th, 2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.5<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.8.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9 </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">September 10th,
            2016<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.6<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04</td>
          <td style="vertical-align: top; text-align: center;">5.8.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9</td>
          <td style="vertical-align: top; text-align: center;">1.4.9</td>
          <td style="vertical-align: top; text-align: center;">1.7.11</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.0.0</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 29th, 2016</td>
          <td style="vertical-align: top; text-align: center;">2.5.7<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.8.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 2nd, 2017</td>
          <td style="vertical-align: top; text-align: center;">2.5.8<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.8.4<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 21st, 2017</td>
          <td style="vertical-align: top; text-align: center;">2.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.9.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 4th, 2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.10.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">June 23rd, 2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.11<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.11.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.12<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">September 2nd,
            2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.12<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.11.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.9<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.12<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">October 28th, 2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.12.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.0.0<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">December 20th,
            2017<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.14<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.12.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.1<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">April 28th, 2018<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.15<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.12.2<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.1<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">July 19th, 2018<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.16<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.12.3<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.1<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">September 30th,
            2018<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.17<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.13.0<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.1<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">December 8th, 2018<br>
          </td>
          <td style="vertical-align: top; text-align: center;">2.5.18<br>
          </td>
          <td style="vertical-align: top; text-align: center;">09<br>
          </td>
          <td style="vertical-align: top; text-align: center;">04<br>
          </td>
          <td style="vertical-align: top; text-align: center;">5.13.1<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.5.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.4.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.7.13<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.2.10<br>
          </td>
          <td style="vertical-align: top; text-align: center;">1.1.1<br>
          </td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 19th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.5.19</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04</td>
          <td style="vertical-align: top; text-align: center;">5.13.2</td>
          <td style="vertical-align: top; text-align: center;">1.5.11</td>
          <td style="vertical-align: top; text-align: center;">1.4.11</td>
          <td style="vertical-align: top; text-align: center;">1.7.14</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.1.1</td>
        </tr>
	<tr>
          <td style="vertical-align: top; text-align: right;">February 9th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.5.20</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04</td>
          <td style="vertical-align: top; text-align: center;">5.13.3</td>
          <td style="vertical-align: top; text-align: center;">1.5.11</td>
          <td style="vertical-align: top; text-align: center;">1.4.11</td>
          <td style="vertical-align: top; text-align: center;">1.7.14</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.1.1</td>
	</tr>
	<tr>
          <td style="vertical-align: top; text-align: right;">May 25th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.5.21</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04</td>
          <td style="vertical-align: top; text-align: center;">5.13.4</td>
          <td style="vertical-align: top; text-align: center;">1.5.11</td>
          <td style="vertical-align: top; text-align: center;">1.4.11</td>
          <td style="vertical-align: top; text-align: center;">1.7.14</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.1.1</td>
        </tr>
	<tr>
          <td style="vertical-align: top; text-align: right;">July 6th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.5.22</td>
          <td style="vertical-align: top; text-align: center;">09</td>
          <td style="vertical-align: top; text-align: center;">04</td>
          <td style="vertical-align: top; text-align: center;">5.13.5</td>
          <td style="vertical-align: top; text-align: center;">1.5.11</td>
          <td style="vertical-align: top; text-align: center;">1.4.11</td>
          <td style="vertical-align: top; text-align: center;">1.7.14</td>
          <td style="vertical-align: top; text-align: center;">1.2.10</td>
          <td style="vertical-align: top; text-align: center;">1.1.1</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">December 16th, 2018</td>
          <td style="vertical-align: top; text-align: center;">2.6.0</td>
          <td style="vertical-align: top; text-align: center;">10</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.0.0</td>
          <td style="vertical-align: top; text-align: center;">1.6.0</td>
          <td style="vertical-align: top; text-align: center;">1.5.0</td>
          <td style="vertical-align: top; text-align: center;">1.8.0</td>
          <td style="vertical-align: top; text-align: center;">1.2.11</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
        </tr>
        <tr>
          <td style="vertical-align: top; text-align: right;">January 19th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.1</td>
          <td style="vertical-align: top; text-align: center;">10</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.0.1</td>
          <td style="vertical-align: top; text-align: center;">1.6.0</td>
          <td style="vertical-align: top; text-align: center;">1.5.0</td>
          <td style="vertical-align: top; text-align: center;">1.8.0</td>
          <td style="vertical-align: top; text-align: center;">1.2.11</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
        </tr>
	<tr>
          <td style="vertical-align: top; text-align: right;">February 9th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.2</td>
          <td style="vertical-align: top; text-align: center;">10</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.0.2</td>
          <td style="vertical-align: top; text-align: center;">1.6.1</td>
          <td style="vertical-align: top; text-align: center;">1.5.1</td>
          <td style="vertical-align: top; text-align: center;">1.8.1</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
        </tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">March 30th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.3</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.1.0</td>
          <td style="vertical-align: top; text-align: center;">1.6.1</td>
          <td style="vertical-align: top; text-align: center;">1.5.1</td>
          <td style="vertical-align: top; text-align: center;">1.8.1</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
        </tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">May 25th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.4</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.1.1</td>
          <td style="vertical-align: top; text-align: center;">1.6.1</td>
          <td style="vertical-align: top; text-align: center;">1.5.1</td>
          <td style="vertical-align: top; text-align: center;">1.8.1</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">July 6th, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.5</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.1.2</td>
          <td style="vertical-align: top; text-align: center;">1.6.1</td>
          <td style="vertical-align: top; text-align: center;">1.5.1</td>
          <td style="vertical-align: top; text-align: center;">1.8.1</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">September 21st, 2019</td>
          <td style="vertical-align: top; text-align: center;">2.6.6</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.0</td>
          <td style="vertical-align: top; text-align: center;">1.6.2</td>
          <td style="vertical-align: top; text-align: center;">1.5.2</td>
          <td style="vertical-align: top; text-align: center;">1.8.2</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">January 12th, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.7</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.1</td>
          <td style="vertical-align: top; text-align: center;">1.6.2</td>
          <td style="vertical-align: top; text-align: center;">1.5.2</td>
          <td style="vertical-align: top; text-align: center;">1.8.2</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">February 8th, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.8</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.2</td>
          <td style="vertical-align: top; text-align: center;">1.6.2</td>
          <td style="vertical-align: top; text-align: center;">1.5.2</td>
          <td style="vertical-align: top; text-align: center;">1.8.2</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">March 22nd, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.9</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.3</td>
          <td style="vertical-align: top; text-align: center;">1.6.2</td>
          <td style="vertical-align: top; text-align: center;">1.5.2</td>
          <td style="vertical-align: top; text-align: center;">1.8.2</td>
          <td style="vertical-align: top; text-align: center;">1.2.12</td>
          <td style="vertical-align: top; text-align: center;">1.1.2</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">May 31st, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.10</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.4</td>
          <td style="vertical-align: top; text-align: center;">1.6.3</td>
          <td style="vertical-align: top; text-align: center;">1.5.3</td>
          <td style="vertical-align: top; text-align: center;">1.8.3</td>
          <td style="vertical-align: top; text-align: center;">1.2.13</td>
          <td style="vertical-align: top; text-align: center;">1.1.3</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">September 5th, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.11</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.5</td>
          <td style="vertical-align: top; text-align: center;">1.6.3</td>
          <td style="vertical-align: top; text-align: center;">1.5.3</td>
          <td style="vertical-align: top; text-align: center;">1.8.3</td>
          <td style="vertical-align: top; text-align: center;">1.2.13</td>
          <td style="vertical-align: top; text-align: center;">1.1.3</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">September 11th, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.12</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.6</td>
          <td style="vertical-align: top; text-align: center;">1.6.3</td>
          <td style="vertical-align: top; text-align: center;">1.5.3</td>
          <td style="vertical-align: top; text-align: center;">1.8.3</td>
          <td style="vertical-align: top; text-align: center;">1.2.13</td>
          <td style="vertical-align: top; text-align: center;">1.1.3</td>
	</tr>
	<tr>
	  <td style="vertical-align: top; text-align: right;">November 8th, 2020</td>
          <td style="vertical-align: top; text-align: center;">2.6.13</td>
          <td style="vertical-align: top; text-align: center;">10.1</td>
          <td style="vertical-align: top; text-align: center;">05</td>
          <td style="vertical-align: top; text-align: center;">6.2.7</td>
          <td style="vertical-align: top; text-align: center;">1.6.3</td>
          <td style="vertical-align: top; text-align: center;">1.5.3</td>
          <td style="vertical-align: top; text-align: center;">1.8.3</td>
          <td style="vertical-align: top; text-align: center;">1.2.13</td>
          <td style="vertical-align: top; text-align: center;">1.1.3</td>
	</tr>
      </tbody>
    </table>
    <br>
    <hr style="width: 100%; height: 2px;"><br>
    <table style="text-align: left; width: 90%; margin-left: auto; margin-right: auto;"
      cellspacing="2" cellpadding="2" border="0">
      <tbody>
        <tr>
          <td style="vertical-align: top;">
            <h3><a name="sym"></a>How symmetric encryption is performed in
              dar/libdar<br>
            </h3>
            <div style="text-align: justify;"> Symmetric encryption are those
              that use a same key/password/passphrase to cipher data and to
              uncipher it, like for example blofish, AES, serpent, camellia,
              twofish and so on.<br>
              <br>
              The user provides:</div>
            <ul>
              <li style="text-align: justify;">a key in the form of a passphrase
                or password</li>
              <li style="text-align: justify;">a cipher algorithm</li>
              <li style="text-align: justify;">a block size (which defaults to
                10 kio)</li>
              <span> </span>
            </ul>
            <span> </span>
            <p style="text-align: justify;"><span>Some additional information is
                stored in clear text in the archive header, information that
                will be used for the key derivation function (KDF):</span></p>
            <div style="text-align: justify;"><span> </span></div>
            <ul style="text-align: justify;">
              <li><span>a salt (random data)</span></li>
              <li><span>a hash algorithm</span></li>
              <li><span>a number of iterations</span></li>
            </ul>
            <div style="text-align: justify;"><span> </span></div>
            <p style="text-align: justify;"><span><strong>Why a KDF?</strong>
                The human provided password/passphrase is usually too simple and
                needs to be "randomized" (in a deterministic manner to be able
                to uncipher the archive later on). This is the reason of the
                KDF, which, from a given key (a string of characters) creates a
                new key using any characters even non printable ones and not
                only alphanumerical ones and punctuation as human do. It will
                pass the key melted with the "salt" into the provided hash
                algorithm the given number of iterations, using at each new
                iteration the resulting key as input for the next round.</span></p>
            <span> </span>
            <p style="text-align: justify;"><span><strong>What is the salt for?</strong>
                Without salt, if we use the same password for many archives, we
                give an attacker a lot of data encrypted with the same key. The
                more data he has, the easier it is to crack this unique key, and
                cracking an archive which is finding the result of the KDF, does
                not lead to crack other archives even if they have been
                encrypted using the same human provided password: Using a
                different salt per archive avoids having the same encryption key
                used for many archives, even if the user provided the same
                password. The salt is stored in clear text beside the hash
                algorithm and the number of iteration in the archive header,
                this is not a problem as the human provided password has still
                to be known for the archive to be uncyphered. For an attacker
                the problem is more complicated as computation done on encrypted
                data to crack the key cannot leverage the fact data has been
                encrypted by the same key thanks to the salt. And the extra work
                due to the salt is proportional to the iteration number times
                the number of archives, thus the more there is data to crack,
                the more the extra work is important, well quite.</span></p>
            <p></p>
            <ul>
            </ul>
            <div style="text-align: justify;">Data to encrypt/decrypt is sliced
              by blocks of given size and each block is provided to the
              encryption engine beside its number inside the archive. To be able
              to encrypt at once 10 kio or more, dar uses the CBC mode (Cipher
              Block Chaining). This mode requires an Initial Vector (IV) to be
              set for each block. The value of this block may be known and
              predictable by an attacker, that's not a problem. Using different
              IV for each block of data avoid having for a given key thus here
              for two different blocks the same encryption result (totally or
              just starting by the same sequence) when clear data is identical
              or starts by the same sequence.<br>
              <br>
              To prevent clear text attack (which is when the attacker has an
              idea of the clear data), each archive starts and ends by an
              elastic buffer, which is pseudo random generated data of variable
              size, both elastic buffers are encrypted with the rest of the real
              data. This way the predictable archive structure is shifted at
              some random place inside the archive, which avoid the possibility
              of a clear text attack (or at least make it much more difficult to
              achieve).<br>
              <br>
              Thanks to the encyrption per block, dar is able to uncipher data
              at random place without having to uncipher the whole archive: only
              the block containing the need data is unciphered. This is
              necessary to face both data corruption and fast restoration of a
              subset of the archive.<br>
              <br>
              Here follows a diagram of the way key, block number, cipher
              algorithm and Initial Vector (IV) are defined:<br>
              <code><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                +------------------- [ algo in CBC mode ]
                -----------------------------&gt; main key handle<br>
                algorithm
                -+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                +---&gt; max key
                len&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
v&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                password ------&gt; [ pkcs5 ] --&gt; hashed_password
                ------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                &nbsp;
                ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                salt
                ----------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;v&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
[
                SHA1/SHA256
                ]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                hash algo
                -----------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
v&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
essiv_password&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                iteration count
                -----+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
v&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
[
                Blowfish/AES256 in ECB mode
                ]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
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essiv
                key
                handle&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                |<br>
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|&nbsp;&nbsp;&nbsp;&nbsp;
                Initialization<br>
                . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|. .
                . . . . . . . . . . . . . | . . . . . . . . . .<br>
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                |<br>
                block_number_in_archive ----------------------------&gt; [
                encrypt ] ------&gt; IV
                -----+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
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                |<br>
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                |<br>
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v&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                v<br>
                data
                ------------------------------------------------------------------------&gt;
                [ encrypt/decrypt ] -----&gt; data<br>
                sliced by block<br>
                of given size</code><br>
              <br>
            </div>
            <br>
          </td>
        </tr>
      </tbody>
    </table>
    <br>
    <hr style="width: 100%; height: 2px;"><br>
    <table style="text-align: left; width: 90%; margin-left: auto; margin-right: auto;"
      cellspacing="2" cellpadding="2" border="0">
      <tbody>
        <tr>
          <td style="vertical-align: top;">
            <h3><a name="asym"></a>How asymmetric encryption is performed in
              dar/libdar<br>
            </h3>
            <div style="text-align: justify;">Dar does not encrypt the whole
              archive with a recipient's public key, but rather randomly chooses
              a (long) password for symmetric encryption (as seen above, except
              it does not need KDF and salt as it can select a much better
              random key than human can do), encrypts that password with the
              recipient's public keys (eventually signing it with your own
              private key) and drops a copy of this ciphered/signed data into
              the archive. At reading time, dar read the archive header to find
              the encrypted password, decrypt it using the user's private key
              then use that password, now in clear, to decrypt the rest of the
              archive with the adhoc symmetric algorithm.<br>
              <br>
              Signing is done on the randomly chosen ciphering key as seen
              above, but also on the catalogue (the table of content located at
              the end of the archive). More precisely the catalogue is
              sha512-hashed and the resulting hash is signed. The catalogue hash
              and its signature are stored encrypted in the archive right after
              the catalogue.<br>
              <br>
              <h4> Why not using only asymmetric encryption end to end? </h4>
              First, for a given fixed amount of data, the resulting ciphered
              data size may vary. Thus sticking ciphered block together in the
              archive would not lead to easily know where a block starts and
              where is located its end. Second, doing that way allows an archive
              to have several different recipients, the password is ciphered for
              each of them and the archive is readable by any specified
              recipient, while they do not share any key. Doing that way has
              very little impact of archive size.<br>
              <br>
              For a multi recipient archive, any recipient has access to the
              signed and encrypted key and could reuses the same encryption key
              which may also be signed by the original sender to build a new
              archive with totally different content, still it should pay
              attention to the fact the catalogue's hash is signed and
              modification should not touch the catalogue in a way the hash
              differ. Last the catalogue contains CRC of file's data/EA/FSA and
              the attacker should pay attention to here too keep the same CRC
              for the whole archive content, not only the catalogue.<br>
              <br>
              Well, this type of attach is pretty accessible by an expert guy,
              but it would take place between an expert guy and his
              friends!&nbsp; See <a href="usage_notes.html#Multi_recipient_signed_archive_weakness">alternatives
                to avoid this pitfall</a><br>
              <br>
              <br>
              <h4>Why not using signing from end to end?</h4>
              First, this can be done without dar, just use gpg on the slices of
              an archive, so there is no advantage in having such feature inside
              dar. The other reason is time, as signing the whole archive would
              be long. it would also be very painful to validate a given archive
              authenticity (time to read a whole archive), here we can leverage
              the fact the archive is encrypted (thus tampering the archive
              would be seen when unciphering it) and that dar uses of several
              mechanismes (compression, clear text CRC) to detect data
              corruption.<br>
            </div>
            <br>
          </td>
        </tr>
      </tbody>
    </table>
    <br>
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