<pre>Internet Engineering Task Force (IETF)                       C. Petrucci
Request for Comments: 6109                                       DigitPA
Category: Informational                                        F. Gennai
ISSN: 2070-1721                                                A. Shahin
                                                                ISTI-CNR
                                                          A. Vinciarelli
                                                              April 2011


  <span class="h1">La Posta Elettronica Certificata - Italian Certified Electronic Mail</span>

Abstract

   Since 1997, the Italian laws have recognized electronic delivery
   systems as legally usable.  In 2005, after two years of technical
   tests, the characteristics of an official electronic delivery
   service, named certified electronic mail (in Italian "Posta
   Elettronica Certificata") were defined, giving the system legal
   standing.

   The design of the entire system was carried out by the National
   Center for Informatics in the Public Administration of Italy
   (DigitPA), followed by efforts for the implementation and testing of
   the service.  The DigitPA has given the Italian National Research
   Council (CNR), and in particular the Institute of Information Science
   and Technologies at the CNR (ISTI), the task of running tests on
   providers of the service to guarantee the correct implementation and
   interoperability.  This document describes the certified email system
   adopted in Italy.  It represents the system as it is at the moment of
   writing, following the technical regulations that were written based
   upon the Italian Law DPR.  November 2, 2005.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It has been approved for publication by the Internet
   Engineering Steering Group (IESG).  Not all documents approved by the
   IESG are a candidate for any level of Internet Standard; see <a href="./rfc5741#section-2">Section</a>
   <a href="./rfc5741#section-2">2 of RFC 5741</a>.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   <a href="http://www.rfc-editor.org/info/rfc6109">http://www.rfc-editor.org/info/rfc6109</a>.





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Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





































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Table of Contents

   <a href="#section-1">1</a>. Introduction ....................................................<a href="#page-5">5</a>
      <a href="#section-1.1">1.1</a>. Scope ......................................................<a href="#page-5">5</a>
      <a href="#section-1.2">1.2</a>. Notational Conventions .....................................<a href="#page-6">6</a>
           <a href="#section-1.2.1">1.2.1</a>. Requirement Conventions .............................<a href="#page-6">6</a>
           <a href="#section-1.2.2">1.2.2</a>. Acronyms ............................................<a href="#page-6">6</a>
           <a href="#section-1.2.3">1.2.3</a>. Terminology and Definitions .........................<a href="#page-7">7</a>
   <a href="#section-2">2</a>. PEC Model .......................................................<a href="#page-8">8</a>
      <a href="#section-2.1">2.1</a>. System-Generated Messages ..................................<a href="#page-8">8</a>
           <a href="#section-2.1.1">2.1.1</a>. Message Types ......................................<a href="#page-10">10</a>
      <a href="#section-2.2">2.2</a>. Basic Structure ...........................................<a href="#page-12">12</a>
           <a href="#section-2.2.1">2.2.1</a>. Access Point .......................................<a href="#page-12">12</a>
           <a href="#section-2.2.2">2.2.2</a>. Incoming Point .....................................<a href="#page-14">14</a>
           <a href="#section-2.2.3">2.2.3</a>. Delivery Point .....................................<a href="#page-16">16</a>
           <a href="#section-2.2.4">2.2.4</a>. Storage ............................................<a href="#page-17">17</a>
           <a href="#section-2.2.5">2.2.5</a>. Provider Service Mailbox ...........................<a href="#page-17">17</a>
           <a href="#section-2.2.6">2.2.6</a>. Provider Service Email Address .....................<a href="#page-17">17</a>
      <a href="#section-2.3">2.3</a>. Log .......................................................<a href="#page-17">17</a>
   <a href="#section-3">3</a>. Message Processing .............................................<a href="#page-18">18</a>
      <a href="#section-3.1">3.1</a>. Access Point ..............................................<a href="#page-18">18</a>
           <a href="#section-3.1.1">3.1.1</a>. Formal Checks on Messages ..........................<a href="#page-18">18</a>
           3.1.2. Non-Acceptance PEC Notification Due to
                  Formal Exceptions ..................................<a href="#page-19">19</a>
           3.1.3. Non-Acceptance PEC Notification Due to
                  Virus Detection ....................................<a href="#page-20">20</a>
           <a href="#section-3.1.4">3.1.4</a>. Server-User Acceptance PEC Notification ............<a href="#page-20">20</a>
           <a href="#section-3.1.5">3.1.5</a>. PEC Transport Envelope .............................<a href="#page-21">21</a>
           <a href="#section-3.1.6">3.1.6</a>. Timeout Delivery Error PEC Notification ............<a href="#page-23">23</a>
      <a href="#section-3.2">3.2</a>. Incoming Point ............................................<a href="#page-24">24</a>
           <a href="#section-3.2.1">3.2.1</a>. Server-Server Acceptance PEC Notification ..........<a href="#page-24">24</a>
           <a href="#section-3.2.2">3.2.2</a>. PEC Anomaly Envelope ...............................<a href="#page-25">25</a>
           <a href="#section-3.2.3">3.2.3</a>. Virus Detection PEC Notification ...................<a href="#page-27">27</a>
           <a href="#section-3.2.4">3.2.4</a>. Virus-Induced Delivery Error PEC notification ......<a href="#page-28">28</a>
      <a href="#section-3.3">3.3</a>. Delivery Point ............................................<a href="#page-29">29</a>
           <a href="#section-3.3.1">3.3.1</a>. Checks on Incoming Messages ........................<a href="#page-29">29</a>
           <a href="#section-3.3.2">3.3.2</a>. Delivery PEC Notification ..........................<a href="#page-29">29</a>
           <a href="#section-3.3.3">3.3.3</a>. Non-Delivery PEC Notification ......................<a href="#page-34">34</a>
      <a href="#section-3.4">3.4</a>. Sender and Receiver Belonging to the Same Domain ..........<a href="#page-34">34</a>
      <a href="#section-3.5">3.5</a>. Example: Complete Transaction between Two PEC Domains .....<a href="#page-34">34</a>
   <a href="#section-4">4</a>. Formats ........................................................<a href="#page-35">35</a>
      <a href="#section-4.1">4.1</a>. Temporal Reference ........................................<a href="#page-35">35</a>
      <a href="#section-4.2">4.2</a>. User Date/Time ............................................<a href="#page-36">36</a>
      <a href="#section-4.3">4.3</a>. Format of a PEC Message Body ..............................<a href="#page-36">36</a>
           <a href="#section-4.3.1">4.3.1</a>. User Readable Text .................................<a href="#page-37">37</a>
           <a href="#section-4.3.2">4.3.2</a>. Original Message ...................................<a href="#page-37">37</a>
           <a href="#section-4.3.3">4.3.3</a>. Certification Data .................................<a href="#page-37">37</a>
      <a href="#section-4.4">4.4</a>. Certification Data Scheme .................................<a href="#page-37">37</a>



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      <a href="#section-4.5">4.5</a>. PEC Providers Directory Scheme ............................<a href="#page-39">39</a>
           <a href="#section-4.5.1">4.5.1</a>. providerCertificateHash Attribute ..................<a href="#page-41">41</a>
           <a href="#section-4.5.2">4.5.2</a>. providerCertificate Attribute ......................<a href="#page-41">41</a>
           <a href="#section-4.5.3">4.5.3</a>. providerName Attribute .............................<a href="#page-41">41</a>
           <a href="#section-4.5.4">4.5.4</a>. mailReceipt Attribute ..............................<a href="#page-42">42</a>
           <a href="#section-4.5.5">4.5.5</a>. managedDomains Attribute ...........................<a href="#page-42">42</a>
           <a href="#section-4.5.6">4.5.6</a>. LDIFLocationURL Attribute ..........................<a href="#page-43">43</a>
           <a href="#section-4.5.7">4.5.7</a>. providerUnit Attribute .............................<a href="#page-43">43</a>
           <a href="#section-4.5.8">4.5.8</a>. LDIFLocationURLObject Object Class .................<a href="#page-44">44</a>
           <a href="#section-4.5.9">4.5.9</a>. Provider Object Class ..............................<a href="#page-44">44</a>
           <a href="#section-4.5.10">4.5.10</a>. LDIF File Example .................................<a href="#page-44">44</a>
   <a href="#section-5">5</a>. Security-Related Aspects .......................................<a href="#page-48">48</a>
      <a href="#section-5.1">5.1</a>. Digital Signature .........................................<a href="#page-48">48</a>
      <a href="#section-5.2">5.2</a>. Authentication ............................................<a href="#page-48">48</a>
      <a href="#section-5.3">5.3</a>. Secure Interaction ........................................<a href="#page-49">49</a>
      <a href="#section-5.4">5.4</a>. Virus .....................................................<a href="#page-49">49</a>
      <a href="#section-5.5">5.5</a>. S/MIME Certificate ........................................<a href="#page-49">49</a>
           <a href="#section-5.5.1">5.5.1</a>. Provider-Related Information (Subject) .............<a href="#page-50">50</a>
           <a href="#section-5.5.2">5.5.2</a>. Certificate Extensions .............................<a href="#page-50">50</a>
           <a href="#section-5.5.3">5.5.3</a>. Example ............................................<a href="#page-51">51</a>
      <a href="#section-5.6">5.6</a>. PEC Providers Directory ...................................<a href="#page-55">55</a>
   <a href="#section-6">6</a>. PEC System Client Technical and Functional Prerequisites .......<a href="#page-55">55</a>
   <a href="#section-7">7</a>. Security Considerations ........................................<a href="#page-55">55</a>
   <a href="#section-8">8</a>. IANA Considerations ............................................<a href="#page-56">56</a>
      <a href="#section-8.1">8.1</a>. Registration of PEC Message Header Fields .................<a href="#page-56">56</a>
           <a href="#section-8.1.1">8.1.1</a>. Header Field: X-Riferimento-Message-ID: ............<a href="#page-56">56</a>
           <a href="#section-8.1.2">8.1.2</a>. Header Field: X-Ricevuta: ..........................<a href="#page-56">56</a>
           <a href="#section-8.1.3">8.1.3</a>. Header Field: X-VerificaSicurezza: .................<a href="#page-57">57</a>
           <a href="#section-8.1.4">8.1.4</a>. Header Field: X-Trasporto: .........................<a href="#page-57">57</a>
           <a href="#section-8.1.5">8.1.5</a>. Header Field: X-TipoRicevuta: ......................<a href="#page-57">57</a>
           <a href="#section-8.1.6">8.1.6</a>. Header Field: X-Mittente: ..........................<a href="#page-58">58</a>
      <a href="#section-8.2">8.2</a>. Registration of LDAP Object Identifier Descriptors ........<a href="#page-58">58</a>
           8.2.1. Registration of Object Classes and
                  Attribute Types ....................................<a href="#page-58">58</a>
   <a href="#section-9">9</a>. References .....................................................<a href="#page-59">59</a>
      <a href="#section-9.1">9.1</a>. Normative References ......................................<a href="#page-59">59</a>
      <a href="#section-9.2">9.2</a>. Informative References ....................................<a href="#page-61">61</a>
   <a href="#section-10">10</a>. Acknowledgments ...............................................<a href="#page-62">62</a>
   <a href="#appendix-A">Appendix A</a>. Italian Fields and Values in English ..................<a href="#page-63">63</a>












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<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>.  Introduction</span>

   Since 1997, the Italian laws have recognized electronic delivery
   systems as legally usable.  In 2005, after two years of technical
   tests, the characteristics of an official electronic delivery
   service, named certified electronic mail (in Italian Posta
   Elettronica Certificata, from now on "PEC") were defined, giving the
   system legal standing.

   This document represents the English version of the Italian
   specifications
   (<a href="http://www.digitpa.gov.it/sites/default/files/normativa/Pec_regole_tecniche_DM_2-nov-2005.pdf">http://www.digitpa.gov.it/sites/default/files/normativa/</a>
   <a href="http://www.digitpa.gov.it/sites/default/files/normativa/Pec_regole_tecniche_DM_2-nov-2005.pdf">Pec_regole_tecniche_DM_2-nov-2005.pdf</a>); the Italian version is the
   normative PEC reference.

   IETF review did not result in community consensus.  Since this
   specification describes existing deployment and implementation, the
   issues identified by the IETF community have not been addressed in
   this document.  However, these issues would need to be addressed
   before a successor to this document could be published.  At a
   minimum, the successor document would need to include:

   * A clear statement of the requirements/goals that need to be
      satisfied by the protocol;

   * A comprehensive diagram and description of the overall message flow
      and delivery sequence required to achieve the requirements;

   * Alignment with traditional terminology for IETF email and security

   * A review of prior art; and

   * A replacement of the unregistered LDAP DN name space used in this
      specification, which may lead to conflict with other registered or
      unregistered names, with a registered name space.

<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>.  Scope</span>

   To ensure secure transactions over the Internet, cryptography can be
   associated with electronic messages in order to provide some
   guarantee on sender identity, message integrity, confidentiality, and
   non-repudiation of origin.  Many end-to-end techniques exist to
   accomplish such goals, and some offer a high level of security.  The
   downside of end-to-end cryptography is the need for an extensive
   penetration of technology in society, because it is essential for
   every user to have asymmetric keys and certificates signed by a
   Certification Authority.  Along with that, users would need to have
   an adequate amount of knowledge regarding the use of such technology.



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   PEC, on the other hand, uses applications running on servers to
   digitally sign messages, thus avoiding the complexity end-to-end
   systems bring about.  By doing so, the user need only have an
   ordinary mail client with which to interact.  The downside is that
   the level of security drops, since the protection does not cover the
   entire transaction.  Nonetheless, application is simpler and does not
   require specific user skills, making it easily more widespread among
   users.

   This document describes PEC's technical aspects and features.  It
   presents the details of the protocol and the messages that are sent
   between service providers, introducing the system adopted by the
   Italian government for the exchange of certified emails.

<span class="h3"><a class="selflink" id="section-1.2" href="#section-1.2">1.2</a>.  Notational Conventions</span>

<span class="h4"><a class="selflink" id="section-1.2.1" href="#section-1.2.1">1.2.1</a>.  Requirement Conventions</span>

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [<a href="#ref-REQ" title="&quot;Key words for use in RFCs to Indicate Requirement Levels&quot;">REQ</a>].

<span class="h4"><a class="selflink" id="section-1.2.2" href="#section-1.2.2">1.2.2</a>.  Acronyms</span>

      CMS:      Cryptographic Message Syntax
      CNIPA:    Italian National Agency for Digital Administration
                (Centro Nazionale per l'Informatica nella Pubblica
                Amministrazione)
      CNR:      Italian National Research Council (Consiglio Nazionale
                delle Ricerche)
      CRL:      Certificate Revocation List
      CRL DP:   Certificate Revocation List Distribution Point
      DNS:      Domain Name Service
      DTD:      Document Type Definition
      FQDN:     Fully Qualified Domain Name
      ISTI:     The Institute of Information Science and Technologies
                at the CNR (Istituto di Scienza e Tecnologie
                dell'Informazione "A.Faedo")
      LDAP:     Lightweight Directory Access Protocol
      LDIF:     LDAP Data Interchange Format
      MIME:     Multipurpose Internet Mail Extensions
      PEC:      Certified Electronic Mail (Posta Elettronica
                Certificata)
      S/MIME:   Secure/MIME
      SMTP:     Simple Mail Transfer Protocol
      TLS:      Transport Layer Security
      XML:      eXtensible Markup Language




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<span class="h4"><a class="selflink" id="section-1.2.3" href="#section-1.2.3">1.2.3</a>.  Terminology and Definitions</span>

   Certification data: A set of data certified by the sender's PEC
   provider that describes the original message.  It includes the date
   and time of dispatch, sender email address, recipient(s) email
   address(es), subject, and message identifier.

   Certified electronic mail: A service based on electronic mail, as
   defined by the [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] and [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>] standards and extensions, which
   permits the transmission of documents produced with informatics
   tools.

   DigitPA: Ex-CNIPA.

   Holder: The person or organization to whom a PEC mailbox is assigned.

   Message sent: A PEC message is considered sent when the sender's PEC
   provider, after several checks, accepts the email and returns a
   server-user acceptance PEC notification to the sender.

   Message received: A PEC message is considered received when it is
   stored in the receiver's mailbox, after which the receiver PEC
   provider returns a delivery PEC notification to the sender.

   Msgid: Is the message identifier generated by the email client, as
   defined in [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>], before the message is submitted to the PEC
   system.

   Ordinary mail: Non-PEC email messages.

   Original message: Is the user-generated message before its arrival to
   the sender Access Point.  The original message is delivered to the
   recipient inside a PEC transport envelope.

   PEC domain: Corresponds to a DNS domain dedicated to the holders'
   mailboxes.

   PEC mailbox: An electronic mailbox for which delivery PEC
   notifications are issued upon reception of PEC messages.  Such a
   mailbox can be defined exclusively within a PEC domain.

   PEC msgid: Is a unique identifier generated by the PEC system, which
   will substitute the msgid.








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   PEC provider: The entity that handles one or more PEC domains with
   their relative points of Access, Reception, and Delivery.  It is the
   holder of the key that is used for signing PEC notifications and
   envelopes, and it interacts with other PEC providers for
   interoperability with other holders.

   PEC provider's key: Is a key released by DigitPA to every PEC
   provider.  It is used to sign PEC notifications and envelopes and to
   authorize access to the PEC providers directory.

   PEC providers directory: Is an LDAP server positioned in an area
   reachable by all PEC service providers.  It constitutes the technical
   structure related to the public list of PEC service providers and
   contains the list of PEC domains and service providers with relevant
   certificates.

   Service mailbox: A mailbox for the sole use of the provider,
   dedicated for the reception of server-server acceptance and virus
   detection PEC notifications.

   Time stamp: Digital evidence with which a temporal reference, that
   can't be repudiated, is attributed to one or more documents.

<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>.  PEC Model</span>

<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>.  System-Generated Messages</span>

   The PEC system generates messages in MIME format composed of a
   descriptive textual part and other [<a href="#ref-MIME1" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies&quot;">MIME1</a>] parts, the number and
   content of which varies according to the type of message generated.

   A system-generated message falls into one of the following
   categories:

   o  Notifications;

   o  Envelopes.

   The message is inserted in an S/MIME v3 structure in CMS format and
   signed with the PEC provider's private key.  The X.509v3 certificate
   associated with the key MUST be included in the aforementioned
   structure.  The S/MIME format used to sign system-generated messages
   is the "multipart/signed" format (.p7s), as described in <a href="#section-3.4.3">section</a>
   <a href="#section-3.4.3">3.4.3</a> of [<a href="#ref-SMIMEV3" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification&quot;">SMIMEV3</a>].

   To guarantee the verifiability of signatures on as many mail clients
   as possible, X.509v3 certificates used by certified email systems
   MUST abide by the profile found in <a href="#section-6.5">section 6.5</a>.



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   In order for the receiving mail client to verify the signature, the
   sender address MUST coincide with the one indicated within the
   X.509v3 certificate.  For this mechanism, PEC transport envelopes
   MUST indicate in the "From:" field a single author's address which is
   different from the one contained in the original message.  To allow
   for better message usability by the receiving user, the author's mail
   address in the original message is inserted as a "display name".  For
   example, a "From:" field such as:

         From: "John Smith" &lt;john.smith@domain.example.com&gt;

   would result in the following "From:" value in the respective PEC
   transport envelope:

         From: "On behalf of: john.smith@domain.example.com"
                                  &lt;certified-mail@provider.example.com&gt;

   Both "From:" and "Sender:" fields MUST contain the same value.  In
   order for replies to be correctly sent back to the proper
   destination, the "Reply-To:" field in the PEC transport envelope MUST
   contain the same unaltered value of the original message's
   "Reply-To:" field.  When it is not explicitly specified in the
   original message, the system that generates the PEC transport
   envelope creates it by extracting the information from the "From:"
   field in the original message.

   When PEC notifications are sent, the system MUST use the original
   message sender's address as the destination address, as is specified
   in the reverse path data of the SMTP protocol.  PEC notifications
   MUST be sent to the sender's PEC mailbox without taking into account
   the "Reply-To:" field, which might be present in the original
   message's header.

   All system-generated PEC messages are identifiable for having a
   specific header defined in PEC according to the type of message
   generated.

   To determine the certification data, the elements used for the actual
   routing of the message are employed.  In SMTP dialog phases, the
   reverse path and forward path data ("MAIL FROM" and "RCPT TO"
   commands) are thus considered certification data of both the sender
   and the recipients, respectively.  Addressing data present in the
   message body ("To:" and "Cc:" fields) are used solely in order to
   discriminate between primary and carbon copy recipients when
   necessary; addressing data present in the "Bcc:" field MUST be
   considered invalid by the system.





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<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


<span class="h4"><a class="selflink" id="section-2.1.1" href="#section-2.1.1">2.1.1</a>.  Message Types</span>

   All system-generated messages inherit their header fields and values
   from the original message, with extra fields added according to the
   type of message generated.

<span class="h5"><a class="selflink" id="section-2.1.1.1" href="#section-2.1.1.1">2.1.1.1</a>.  PEC Notifications</span>

   They have the purpose of informing the sending user and interacting
   providers of the progress the message is making within the PEC
   network.

<span class="h6"><a class="selflink" id="section-2.1.1.1.1" href="#section-2.1.1.1.1">2.1.1.1.1</a>.  Success PEC Notifications</span>

   These notifications indicate an acknowledgment on the provider's side
   for the reception or handling of a PEC message.  More specifically,
   it can indicate one of three situations: server-user acceptance,
   server-server acceptance, or delivery.

   Added header fields are:

   o  X-Ricevuta:

   o  X-Riferimento-Message-ID:

   The field "X-Ricevuta:" indicates the type of PEC notification
   contained in the message, whereas "X-Riferimento-Message-ID:"
   contains the message identifier generated by the mail client (msgid).

   Body contents differ according to notification type.  This is
   described more thoroughly in <a href="#section-3">section 3</a>.

   o  A server-user acceptance PEC notification informs the user that
      his provider has accepted the message and will be taking care of
      passing it on to the provider(s) of the addressee(s).

   o  A server-server acceptance PEC notification is an inter-provider
      communication only, it MUST NOT be sent to the users.  With this
      notification, the receiving provider simply informs the sending
      one that it has received a PEC message, and will take the
      responsibility of forwarding it to the addressee(s).  From then
      on, the sender provider is no longer held responsible as to the
      whereabouts of the message, but is limited to notifying its user
      of the success or failure of delivery.

   o  Delivery PEC notifications take place as the final communication
      of a transaction, indicating overall success in handing the
      message over to the addressee(s).



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<span class="h6"><a class="selflink" id="section-2.1.1.1.2" href="#section-2.1.1.1.2">2.1.1.1.2</a>.  Delay PEC Notifications</span>

   Delay PEC notifications are sent out 12 hours after a message has
   been dispatched from the sending provider, and no server-server
   acceptance or delivery PEC notification has been received.  These
   have the sole purpose of notifying the user of the delay.

   If another 12 hours go by without any sign of a server-server
   acceptance or delivery PEC notification (amounting to a 24-hour
   delay), another delay PEC notification is dispatched to the user
   informing him of the possible delivery failure.  The provider will
   not keep track of the delay any further.

<span class="h6"><a class="selflink" id="section-2.1.1.1.3" href="#section-2.1.1.1.3">2.1.1.1.3</a>.  Failure PEC Notifications</span>

   They are sent when there is some error in transmission or reception.
   More specifically, a failure PEC notification can indicate either a
   formal-exception error or a virus detection.

   Added header fields are:

   o  X-Ricevuta:

   o  X-Riferimento-Message-ID:

   o  X-VerificaSicurezza: [optional]

   "X-Ricevuta:" and "X-Riferimento-Message-ID:" have the same role as
   indicated in <a href="#section-2.1.1.1.1">section 2.1.1.1.1</a> (Success Notifications).
   "X-VerificaSicurezza:" (security verification) is an optional header
   field, used for virus-related PEC notifications.

   Body contents differ according to notification type.  This is
   described more thoroughly in <a href="#section-3">section 3</a>.

<span class="h5"><a class="selflink" id="section-2.1.1.2" href="#section-2.1.1.2">2.1.1.2</a>.  PEC Envelopes</span>

   Messages entering the PEC network are inserted within specific PEC
   messages, called envelopes, before they are allowed to circulate
   further within the network.  These envelopes MUST inherit the
   following header fields, along with their unmodified values, from the
   message itself:

   o  Received:

   o  To:

   o  Cc:



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   o  Return-Path:

   o  Reply-To: (if present)

   Depending on the type of message requesting admission into the PEC
   network, it will be inserted in either a PEC transport envelope or a
   PEC anomaly envelope.  Distinction will be possible through the
   addition of the "X-Trasporto:" header field.

<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>.  Basic Structure</span>

                +-------------+               +------------+
                |    +--+     |               |            |
                |    |AP|     |      PEC      |            |
      +----+    |    +--+     |   messages &amp;  | +---+ +--+ |    +----+
      |user|&lt;--&gt;|             |&lt;-------------&gt;| |InP| |DP| |&lt;--&gt;|user|
      +----+    | +--+  +---+ | notifications | +---+ +--+ |    +----+
                | |DP|  |InP| |               |            |
                | +--+  +---+ |               |            |
                +-------------+               +------------+
                     PEC                            PEC
                    sender                        receiver
                   provider                       provider

      where:

      AP = Access Point
      DP = Delivery Point
      InP = Incoming Point

<span class="h4"><a class="selflink" id="section-2.2.1" href="#section-2.2.1">2.2.1</a>.  Access Point</span>

   This is what the user client at the sender side interacts with,
   giving the user access to PEC services set up by the provider.

   Such access MUST be preceded by user authentication on the system
   (see <a href="#section-5.2">section 5.2</a>).  The Access Point receives the original messages
   its user wishes to send, runs some formal checks, and acts according
   to the outcome:

   o  if the message passes all checks, the Access Point generates a
      server-user acceptance PEC notification and inserts the original
      message inside a PEC transport envelope;

   o  if a formal exception is detected, the Access Point refuses the
      message and emits the relevant non-acceptance PEC notification
      (see <a href="#section-3.1.1">section 3.1.1</a>);




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   o  if a virus is detected, the Access Point generates a non-
      acceptance PEC notification and inserts the original message as is
      in the provider's special store.

   Generation of the server-user acceptance notification indicates to
   the user that the message was accepted by the system, certifying also
   the date and time of the event.  The notification MUST contain user-
   readable text, and an XML part containing the certification data.
   The notification MAY also contain other attachments for extra
   features offered by the provider.

   Using the data available in the PEC providers directory (see <a href="#section-4.5">section</a>
   <a href="#section-4.5">4.5</a>), the Access Point runs checks on every recipient in the "To:"
   and "Cc:" fields present in the original message to verify whether
   they belong to the PEC infrastructure or to non-PEC domains.  Such
   checks are done by verifying the existence, through a case-
   insensitive search, of the recipients' domains in the
   "managedDomains" attribute found within the PEC providers directory.
   Therefore, the server-user acceptance PEC notification (and relevant
   certification data) relates to, for each address, the typology of its
   domain; PEC or non-PEC.

   The message identifier (PEC msgid) of accepted original messages
   within the PEC infrastructure MUST be unambiguous in order to consent
   correct tracking of messages and relative PEC notifications.  The
   format of such an identifier is:

        [alphanumeric string]@[provider mail domain]

   or:

        [alphanumeric string]@[FQDN mail server]

   Therefore, both the original message and the corresponding PEC
   transport envelope MUST contain the following header field:

        Message-ID: &lt;[unique identifier]&gt;

   When an email client that is interacting with the Access Point has
   already inserted a message identifier (msgid) in the original
   message, that msgid SHALL be substituted by a PEC msgid.  In order to
   allow the sender to link the message sent with the relative PEC
   notifications, the msgid MUST be inserted in the original message as
   well as the relative PEC notifications and transport envelope.  If
   present, the msgid is REQUIRED in the original message's header by
   adding the following header field:

        X-Riferimento-Message-ID: &lt;[msgid]&gt;



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   which will also be inserted in the PEC transport envelope and
   notifications, and related in the certification data (see <a href="#section-4.4">section</a>
   <a href="#section-4.4">4.4</a>).

<span class="h4"><a class="selflink" id="section-2.2.2" href="#section-2.2.2">2.2.2</a>.  Incoming Point</span>

   This point permits the exchange of PEC messages and notifications
   between PEC providers.  It is also the point through which ordinary
   mail messages can be inserted within the system of certified mail.

   The exchange of messages between providers takes place through SMTP-
   based transactions, as defined in [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>].  If SMTP communication
   errors occur, they MAY be handled using the standard error
   notification mechanisms, as provided by SMTP in [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>] and
   [<a href="#ref-SMTP-DSN" title="&quot;Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)&quot;">SMTP-DSN</a>].  The same mechanism is also adopted for handling
   transitory errors, that result in long idling periods, during an SMTP
   transmission phase.  In order to guarantee that an error is returned
   to the user, as defined in <a href="#section-3.3.3">section 3.3.3</a>, the system that handles PEC
   traffic MUST adopt a time limit for message idleness equal to 24
   hours.

   Once a message arrives, the Incoming Point runs the following list of
   checks and operations:

   o  verifies correctness and type of the incoming message;

   o  if the incoming message is a correct and undamaged PEC transport
      envelope:

      - emits a server-server acceptance PEC notification towards the
        sender provider (<a href="#section-3.2.1">section 3.2.1</a>);

      - forwards the PEC transport envelope to the Delivery Point
        (<a href="#section-3.3">section 3.3</a>).

   o  if the incoming message is a correct and undamaged PEC
      notification, forwards the notification to the Delivery Point.

   o  if the incoming message does not conform to the prerequisites of a
      correct and undamaged PEC transport envelope or notification, but
      comes from a PEC provider, i.e., passes the verifications
      regarding existence, origin, and validity of the signature, then
      the message MUST be propagated towards the recipient.

      Therefore, the Incoming Point:

      -  inserts the incoming message in a PEC anomaly envelope (<a href="#section-3.2.2">section</a>
         <a href="#section-3.2.2">3.2.2</a>);



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      -  forwards the PEC anomaly envelope to the Delivery Point.

   o  if the incoming message does not originate from a PEC system,
      i.e., fails verifications regarding existence, origin, and
      validity of the signature, then the message will be treated as
      ordinary email, and, if propagated to the recipient:

      - is inserted in a PEC anomaly envelope (<a href="#section-3.2.2">section 3.2.2</a>);

      - the PEC anomaly envelope is forwarded to the Delivery Point.

      The server-server acceptance PEC notification is generated by the
      receiving provider and sent to the sending provider.  Its purpose
      is to keep track of the message in its transition from one
      provider to another, and is therefore strictly intra-provider
      communication; the end user knows nothing about it.

      To check the correctness and integrity of a PEC transport envelope
      or notification, the Incoming Point runs the following tests:

   o  Signature existence - the system verifies the presence of an
      S/MIME signature structure within the incoming message;

   o  Signature origin - the system verifies whether or not the
      signature belongs to a PEC provider by extracting the certificate
      used for signing and verifying its presence in the PEC providers
      directory.  To ease the check, it is possible to calculate the
      certificate's [<a href="#ref-SHA1" title="&quot;US Secure Hash Algorithm 1 (SHA1)&quot;">SHA1</a>] hash value and perform a case-insensitive
      search of its hexadecimal representation within the
      "providerCertificateHash" attribute found in the PEC providers
      directory.  This operation allows one to easily identify the
      sender provider for subsequent and necessary matching checks
      between the extracted certificate and the one present in the
      provider's record;

   o  Signature validity - S/MIME signature correctness is verified by
      recalculating the signature value, checking the entire
      certification path, and verifying the [<a href="#ref-CRL" title="&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile&quot;">CRL</a>] and temporal validity
      of the certificate.  In case some caching mechanism is used for
      CRL contents, an update interval MUST be adopted so that the most
      up-to-date data is guaranteed, thus minimizing the possible delay
      between a publication revocation by the Certification Authority
      and the variation acknowledgment by the provider;

   o  Formal correctness - the provider performs sufficient and
      necessary checks to guarantee that the incoming message is
      compliant with the formats specified in this document (PEC
      transport envelope and notifications).



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      If a virus-infected PEC transport envelope passes the checks just
      mentioned, it is still considered correct and undamaged.  The
      presence of the virus will be detected in a second phase, during
      which the contents of the PEC transport envelope are verified.
      Thus, the Incoming Point will refrain from forwarding the message
      to the recipient, instead sending the appropriate PEC notification
      of non-delivery and storing the virus-infected message in the
      provider's special storage.

      In case ordinary mail messages are received, the PEC provider
      SHALL perform virus checks in order to prevent the infiltration of
      potentially dangerous mail messages within the PEC system.  If a
      virus is detected in an ordinary mail message, the latter can be
      discarded at the Incoming Point before it enters the PEC system.
      In other words, no special treatment is reserved for the error; it
      is handled in a manner that is conformant to the procedures
      usually followed for messages going through the Internet.

      When the receiving provider detects a virus inside a PEC transport
      envelope during the reception phase, it emits a virus detection
      PEC notification to the sending provider, which then realizes its
      checks failed to detect that virus.  When this happens, the
      sending provider MUST:

   o  check what virus typologies were not detected by its own antivirus
      to verify the possibility of interventions

   o  send a virus-induced non-delivery PEC notification to the sender's
      mailbox.

<span class="h4"><a class="selflink" id="section-2.2.3" href="#section-2.2.3">2.2.3</a>.  Delivery Point</span>

   This point is the point that receives messages from the Incoming
   Point and forwards them to the final recipient.

   It MUST run a series of tests on received messages before forwarding
   them to the user (see <a href="#section-3.3.1">section 3.3.1</a>).  It first verifies the typology
   of the message and decides whether or not a PEC notification should
   be issued to the sender.  The delivery PEC notification (<a href="#section-3.3.2">section</a>
   <a href="#section-3.3.2">3.3.2</a>) is emitted after the message was delivered to the recipient's
   PEC mailbox and only at reception of a valid PEC transport envelope
   (sections <a href="#section-2.2.2">2.2.2</a> and <a href="#section-3.1.5">3.1.5</a>).

   In all other cases, such as PEC anomaly envelopes and PEC
   notifications, the delivery PEC notification is not emitted.
   Regardless, the message received from the Delivery Point MUST be
   delivered unmodified to the recipient's mailbox.




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   The delivery PEC notification indicates to the sender that the
   message sent was in fact conveyed to the specified recipient's
   mailbox and certifies the date and time of delivery through use of
   user-readable text and an XML part containing certification data,
   along with other possible attachments added for extra features
   offered by the provider.

   If a PEC transport envelope received at the Delivery Point can't be
   delivered to the destination mailbox, the Delivery Point emits a non-
   delivery PEC notification (<a href="#section-3.3.3">section 3.3.3</a>).  If, on the other hand,
   the delivery error concerns a message that arrives from Internet
   (i.e., a non-PEC message), no such notification is emitted.

<span class="h4"><a class="selflink" id="section-2.2.4" href="#section-2.2.4">2.2.4</a>.  Storage</span>

   Each provider MUST dedicate a special storage for the deposition of
   any virus-infected messages encountered.  Whether the virus be
   detected by the sender's Access Point or the receiver's Incoming
   Point, the provider that detects it MUST store the mail message in
   its own storage, and keep it for 30 months.

<span class="h4"><a class="selflink" id="section-2.2.5" href="#section-2.2.5">2.2.5</a>.  Provider Service Mailbox</span>

   For exclusive use of the provider, dedicated to the reception of PEC
   notifications in two cases only:

   o  server-server acceptance notification; and

   o  virus detection notification.

<span class="h4"><a class="selflink" id="section-2.2.6" href="#section-2.2.6">2.2.6</a>.  Provider Service Email Address</span>

   Each provider MUST register a special purpose email address for use
   when sending PEC transport envelopes and notifications, as delineated
   in <a href="#section-3">section 3</a>.  This address MAY coincide with that of the service
   mailbox described in <a href="#section-2.2.5">section 2.2.5</a>.

<span class="h3"><a class="selflink" id="section-2.3" href="#section-2.3">2.3</a>.  Log</span>

   The server administrator MUST keep track of any and all operations
   carried out in a specific message log file.  The information kept in
   the log for each operation is the following:

   o  message identifier (msgid)

   o  date and time of event

   o  sender of original message



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   o  recipient(s) of original message

   o  subject of original message

   o  event type (reception, delivery, PEC notification emission, etc.)

   o  message identifiers of related generated messages

   o  sending provider

   The service provider MUST store this data and preserve it unmodified.
   Italian laws have specified that the service provider retain the data
   for 30 months.

<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>.  Message Processing</span>

<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>.  Access Point</span>

   The Access Point acts as a submission service as defined in
   [<a href="#ref-SUBMISSION" title="&quot;Message Submission for Mail&quot;">SUBMISSION</a>].

<span class="h4"><a class="selflink" id="section-3.1.1" href="#section-3.1.1">3.1.1</a>.  Formal Checks on Messages</span>

   When the Access Point receives a message the user wishes to send, it
   MUST guarantee said message's formal conformity as defined in
   [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>], and verify that the:

   o  [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] header section contains a "From:" header field holding an
      [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] compliant email address;

   o  [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] header section contains a "To:" header field holding one
      or more [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] compliant email addresses;

   o  sender's address, specified in the SMTP reverse path, coincides
      with the one in the message's "From:" header field;

   o  recipients' addresses specified in the SMTP forward path coincide
      with the ones present in the "To:" or "Cc:" header fields of the
      message;

   o  "Bcc:" header field does not contain any value;

   o  total message size falls within the limits accepted by the
      provider.  Such limits apply depending on the number of recipients
      as well; by multiplying it to the message size, the outcome MUST
      fall within the limits accepted by the provider.  Italian laws
      have specified this limit as being 30 MB.




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   If the message does not pass the tests, the Access Point MUST NOT
   accept the message within the PEC system, thus emitting the relative
   PEC notification of non-acceptance.

<span class="h4"><a class="selflink" id="section-3.1.2" href="#section-3.1.2">3.1.2</a>.  Non-Acceptance PEC Notification Due to Formal Exceptions</span>

   When the Access Point cannot forward the message received due to
   failure in passing formal checks, the sender is notified of such an
   outcome.  If the error is caused by the message failing size checks,
   a non-acceptance PEC notification is sent as long as the size remains
   bound by a certain limit.  If the size exceeds said limit, error
   handling is left to SMTP.

   The notification header will contain the following fields:

        X-Ricevuta: non-accettazione
        Date: [date of notification emission]
        Subject: AVVISO DI NON ACCETTAZIONE: [original subject]
        From: posta-certificata@[mail domain]
        To: [original sender]
        X-Riferimento-Message-ID: [msgid]

   The notification body will contain a text part that constitutes the
   actual notification in readable format according to a model that
   relates the following information:

      Error in message acceptance
      On [date] at [time] ([time zone]), in the message "[subject]"
      originating from "[original sender]" and addressed to:
      [recipient_1]
      [recipient_2]
      [recipient_n]
      a problem was detected that prevents its acceptance due to
      [error description].
      The message was not accepted.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification information is inserted in an XML file to be
   added to the notification body, thus allowing automatic checks on the
   message (<a href="#section-4.4">section 4.4</a>).  Parsing MUST be done on the XML part only.
   Additional parts MAY be included by the provider for provider-
   specific services.  Regardless, the original message MUST NOT be
   included.  The message MUST follow the format described in <a href="#section-4.3">section</a>
   <a href="#section-4.3">4.3</a>.






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<span class="h4"><a class="selflink" id="section-3.1.3" href="#section-3.1.3">3.1.3</a>.  Non-Acceptance PEC Notification Due to Virus Detection</span>

   The Access Point MUST run some tests on the content of messages it
   receives from its users and reject them if a virus is detected.  In
   which case, a virus-detection-induced non-acceptance PEC notification
   MUST be emitted to clearly inform the user of the reason the message
   was refused.

   The notification header contains the following fields:

      X-Ricevuta: non-accettazione
      X-VerificaSicurezza: errore
      Date: [notification emission date]
      Subject: AVVISO DI NON ACCETTAZIONE PER VIRUS: [original
               subject]
      From: posta-certificata@[mail domain]
      To: [original sender]
      X-Riferimento-Message-ID: [msgid]

   The body contains a readable text part according to the following
   model:

      Error in message acceptance due to virus presence
      On [date] at [time] ([time zone]), in the message "[subject]"
      originating from "[original sender]" and addressed to:
      [recipient_1]
      [recipient_2]
      [recipient_n]
      a security problem was detected [ID of detected content type].
      The message was not accepted.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file added to the
   notification to allow for automatic checks (<a href="#section-4.4">section 4.4</a>).  Parsing
   MUST be done on the XML part only.  Additional parts MAY be included
   by the provider for provider-specific services.  Regardless, the
   original message MUST NOT be included.  The message MUST follow the
   format described in <a href="#section-4.3">section 4.3</a>.

<span class="h4"><a class="selflink" id="section-3.1.4" href="#section-3.1.4">3.1.4</a>.  Server-User Acceptance PEC Notification</span>

   The server-user acceptance PEC notification is a message sent to the
   sender by his server, containing date and time of message acceptance
   into the system, sender and recipient data, and subject.






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   The header contains the following fields:

      X-Ricevuta: accettazione
      Date: [actual date of server-user acceptance]
      Subject: ACCETTAZIONE: [original subject]
      From: posta-certificata@[mail domain]
      To: [original sender]
      X-Riferimento-Message-ID: [msgid]

   The message body contains a text part that constitutes the
   notification in readable format, according to a model that relates
   the following information:

      Server-User Acceptance PEC notification
      On [date] at [time] ([time zone]), the message "[subject]"
       originating from "[original sender]" and addressed to:
      [recipient_1] (["certified mail" | "ordinary mail"])
      [recipient_2] (["certified mail" | "ordinary mail"])
      [recipient_n] (["certified mail" | "ordinary mail"])
      was accepted by the system and forwarded to the recipient(s).
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file added to the
   notification message, allowing automatic checks on it (<a href="#section-4.4">section 4.4</a>).
   Parsing MUST be done on the XML part only.  Additional parts MAY be
   included by the provider for provider-specific services.  The message
   MUST follow the format described in <a href="#section-4.3">section 4.3</a>.

<span class="h4"><a class="selflink" id="section-3.1.5" href="#section-3.1.5">3.1.5</a>.  PEC Transport Envelope</span>

   A PEC transport envelope is a message generated by the Access Point
   that contains the original message as well as certification data.

   As mentioned in <a href="#section-2.1.1.2">section 2.1.1.2</a>, the PEC transport envelope inherits
   from the original message the values of the following header fields,
   which MUST be related unmodified:

   o  Received:

   o  To:

   o  Cc:

   o  Return-Path:

   o  Reply-To: (if present)




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   On the other hand, the following fields MUST be modified, or inserted
   if necessary:

      X-Trasporto: posta-certificata
      Date: [actual date of server-user acceptance]
      Subject: POSTA CERTIFICATA: [original subject]
      From: "On behalf of: [original sender]"
                           &lt;certified-mail@[mail_domain]&gt;
      Reply-To: [original sender] (inserted only if not present)
      Message-ID: [PEC msgid generated as in <a href="#section-2.2.1">section 2.2.1</a>]
      X-Riferimento-Message-ID: [msgid]
      X-TipoRicevuta: [completa/breve/sintetica]

   The "X-TipoRicevuta:" field indicates the type of delivery PEC
   notification the sender wishes to receive -- complete, brief, or
   concise.

   The body of the PEC transport envelope contains a text part that
   constitutes the readable format of the message according to a model
   that relates the following certification data:

      Certified mail message
      On [date] at [time] ([time zone]), the message "[subject]" was
      sent by "[original sender]" and addressed to:
      [recipient_1]
      [recipient_2]
      [recipient_n]
      The original message is included in attachment.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   Within the PEC transport envelope, the entire, non-modified original
   message is inserted in a format compliant with [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] (except for
   what has been said regarding the message identifier), as well as an
   XML part, which contains the certification data that was already
   related in text format, and information on the type of message and
   PEC notification requested (<a href="#section-4.4">section 4.4</a>).  Parsing MUST be done on
   the XML part only.  Additional parts MAY be included by the provider
   for provider-specific services.  The message MUST follow the format
   described in <a href="#section-4.3">section 4.3</a>.

   Note that the routing data of the PEC transport envelope (forward and
   reverse paths) remain unaltered.








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<span class="h4"><a class="selflink" id="section-3.1.6" href="#section-3.1.6">3.1.6</a>.  Timeout Delivery Error PEC Notification</span>

   If the sending provider doesn't receive a server-server acceptance or
   delivery PEC notification from the receiving provider within 12 hours
   of the message dispatch, it informs the user that the recipient's
   provider might not be able to deliver the message.  In case the
   sending provider doesn't receive a delivery PEC notification within
   24 hours after message dispatch, it emits another non-delivery PEC
   notification to the user by the 24-hour timeout, but not before 22
   hours have passed.

   Such a communication takes place through a PEC notification of non-
   delivery due to timeout, the header of which contains the following
   fields:

      X-Ricevuta: preavviso-errore-consegna
      Date: [date of notification emission]
      Subject: AVVISO DI MANCATA CONSEGNA PER SUP.  TEMPO MASSIMO:
               [original subject]
      From: posta-certificata@[mail domain]
      To: [original recipient]
      X-Riferimento-Message-ID: [msgid]

   The body of the first non-delivery PEC notification (12-hour timeout)
   contains a text part that represents the readable format of the
   notification which will relate the following data:

      Non-delivery PEC notification
      On [date] at [time] ([time zone]), the message
      "[subject]" originating from "[original sender]"
      and addressed to "[recipient]"
      has not been delivered within the first 12 hours following
      its dispatch.  Not excluding that the message might eventually
      be delivered, it is deemed useful to consider that dispatch
      might not have a positive outcome.  The system will see to
      sending another non-delivery PEC notification if in the
      following twelve hours no confirmation is received from the
      recipient.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   On the other hand, 24-hour-timeout induced PEC notifications, which
   have the same header as described above, will have the following text
   in their body:







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      Non-delivery PEC notification
      On [date] at [time] ([time zone]), the message
      "[subject]" originating from "[original sender]"
      and addressed to "[recipient]"
      has not been delivered within 24 hours of its dispatch.

      The transaction is deemed to be considered terminated with a
      negative outcome.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file added to both
   PEC notification types to allow automatic checks (<a href="#section-4.4">section 4.4</a>).

   Parsing MUST be done on the XML part only.  Additional parts MAY be
   added for services supplied by the PEC provider.  Regardless, the
   original message MUST NOT be included.  The message MUST follow the
   format described in <a href="#section-4.3">section 4.3</a>.

   A timeout PEC notification is generated if one of the following
   scenarios occurs:

   o  the sending provider receives a server-server acceptance PEC
      notification during the first 12 hours following message dispatch,
      but does not receive a delivery PEC notification at all.  In this
      case, it would be a 24-hour timeout PEC notification.

   o  the sending provider does not receive a server-server acceptance
      PEC notification, but receives a delivery PEC notification after
      12 hours and before the 24-hour timeout.  In this case it would be
      a 12-hour timeout PEC notification.

   o  the sending provider doesn't receive either a server-server
      acceptance or a delivery PEC notification.  In this case, two
      timeout PEC notifications are generated; a 12-hour and a 24-hour
      timeout PEC notification.

<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>.  Incoming Point</span>

<span class="h4"><a class="selflink" id="section-3.2.1" href="#section-3.2.1">3.2.1</a>.  Server-Server Acceptance PEC Notification</span>

   When correct PEC transport envelopes (as defined in <a href="#section-2.2.2">section 2.2.2</a>.)
   are exchanged between PEC providers, the receiver MUST send a server-
   server acceptance PEC notification to the sender.  The single
   dispatched notification concerns all recipients who belong to the
   same provider, and to whom the incoming message was addressed, as
   stated in the routing data (forward and reverse paths) of the SMTP
   transaction.  Within the certification data of a single server-server



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   acceptance PEC notification, all recipients of the message to which
   it refers are listed.  In general, when receiving a PEC transport
   envelope, each provider MUST emit one or more server-server
   acceptance PEC notifications to cover, in absence of SMTP transport
   errors, all the recipients in its jurisdiction.

   The header of a server-server acceptance PEC notification contains
   the following fields:

      X-Ricevuta: presa-in-carico
      Date: [date of server-server acceptance]
      Subject: PRESA IN CARICO: [original subject]
      From: posta-certificata@[mail domain]
      To: [sender provider service mailbox]
      X-Riferimento-Message-ID: [msgid]

   The provider's service email address is obtained from the PEC
   providers directory during the necessary queries made in the
   signature verification stage.

   The body contains a text part that follows the underlying model:

      Server-server acceptance PEC notification
      On [date] at [time] ([time zone]), the message "[subject]"
      originating from "[original sender]" and addressed to:
      [recipient_1]
      [recipient_2]
      [recipient_n]
      was accepted by the system.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file which is added
   to the notification message to allow for automatic checks (<a href="#section-4.4">section</a>
   <a href="#section-4.4">4.4</a>).  Parsing MUST be done on the XML part only.  Additional parts
   MAY be added by the provider for provider-specific services.  The
   message MUST follow the format described in <a href="#section-4.3">section 4.3</a>.

<span class="h4"><a class="selflink" id="section-3.2.2" href="#section-3.2.2">3.2.2</a>.  PEC Anomaly Envelope</span>

   If the tests on an incoming message detect an error, or the message
   is identified as being ordinary mail and the provider is set to
   forward it to the recipient, the system MUST insert such a message in
   a PEC anomaly envelope.  Before delivery, the entire message received







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   at the Incoming Point is inserted in a format compliant with [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]
   as a [<a href="#ref-MIME1" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies&quot;">MIME1</a>] part inside a new message that MUST inherit the
   unmodified values for the following header fields from the received
   message:

   o  Received:

   o  To:

   o  Cc:

   o  Return-Path:

   o  Message-ID:

   Whereas, the following header fields MUST be modified or inserted:

      X-Trasplorto: errore
      Date: [mlessage arrival date]
      Subject: ANOMALIA MESSAGGIO: [original subject]
      From: "On behalf of: [original sender]"
                             &lt;posta-certificata@[mail_domain]&gt;
      Reply-To: [original sender (inserted only if not already
                present)]

   The body contains a user-readable text part according to a model that
   relates the following data:

      Message anomaly
      On [date] at [time] ([time zone]), the message "[subject]"
      originating from "[original sender]" and addressed to:
      [recipient_1]
      [recipient_2]
      [recipient_n]
      was received.
      The data has not been certified due to the following error:
      [concise description of error]
      The original message is attached.

   Due to uncertainty regarding origin and/or conformity of the message
   received, the PEC anomaly envelope MUST NOT contain [<a href="#ref-MIME1" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies&quot;">MIME1</a>] parts
   other than the entire message that arrived at the Incoming Point.

   Note that the routing data of such an envelope (forward and reverse
   paths) remain unaltered.  Doing so guarantees both message forwarding
   to the recipients, and reception of SMTP error notifications, if any
   occur, by the sender (as specified in [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>] and [<a href="#ref-SMTP-DSN" title="&quot;Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)&quot;">SMTP-DSN</a>]).




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<span class="h4"><a class="selflink" id="section-3.2.3" href="#section-3.2.3">3.2.3</a>.  Virus Detection PEC Notification</span>

   If the Incoming Point receives virus-infected PEC messages, it MUST
   NOT forward them.  Rather it MUST inform the sending provider, which
   will in turn inform the sending user, of the failed transmission.  A
   separate PEC notification of virus detection MUST be sent on behalf
   of every recipient within the provider's domain.

   In case a virus is detected during the reception phase of a message
   whose origin was asserted through sender signature verification, the
   system generates a virus-detected PEC notification indicating the
   error found, and sends it to the sending provider's service mailbox.

   The header of this PEC notification contains the following fields:

      X-Ricevuta: rilevazione-virus
      X-Mittente: [original sender]
      Date: [date of notification emission]
      Subject: PROBLEMA DI SICUREZZA: [original subject]
      From: posta-certificata@[mail domain]
      To: [sender provider notifications]
      X-Riferimento-Message-ID: [msgid]

   The body contains a readable text part according to a model that
   relates the following data:

      Virus detection PEC notification
      On [date] at [time] ([time zone]), in the message "[subject]"
      originating from "[original sender]" and addressed to
      "[recipient]"
      a security problem was detected [ID of content type detected].
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file and added to
   the notification to allow for automatic checks (<a href="#section-4.4">section 4.4</a>).
   Parsing MUST be done on the XML part only.  Additional parts MAY be
   included by the provider for provider-specific services.  Regardless,
   the original message MUST NOT be included.  The message MUST follow
   the format described in <a href="#section-4.3">section 4.3</a>.

   The message body MUST contain the reason for which the transmission
   could not be completed.








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<span class="h4"><a class="selflink" id="section-3.2.4" href="#section-3.2.4">3.2.4</a>.  Virus-Induced Delivery Error PEC notification</span>

   At the reception of a virus detection PEC notification from the
   receiving provider, the sender provider emits a non-delivery PEC
   notification to the sending user.

   The header for this notification contains the following fields:

      X-Ricevuta: errore-consegna
      X-VerificaSicurezza: errore
      Date: [date of notification emission]
      Subject: AVVISO DI MANCATA CONSEGNA PER VIRUS: [original
               subject]
      From: posta-certificata@[mail domain]
      To: [original sender]
      X-Riferimento-Message-ID: [msgid]

   The body contains a readable text part according to a model that
   relates the following data:

      Delivery error PEC notification due to virus
      On [date] at [time] ([time zone]), in the message "[subject]"
      addressed to "[recipient]"
      a security problem was detected [ID of content type detected
      by the anti-virus].
      The message was not delivered.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   All the information necessary for the construction of such a PEC
   notification can be obtained from the correlated virus-detected PEC
   notification.

   The same certification data is inserted in an XML file and added to
   the notification message to allow for automatic checks (<a href="#section-4.4">section 4.4</a>).
   Parsing MUST be done on the XML part only.  Additional parts MAY be
   included by the provider for provider-specific services.  The reason
   the transaction was not completed MUST be specified in the message,
   which MUST follow the format described in <a href="#section-4.3">section 4.3</a>.












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<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>.  Delivery Point</span>

<span class="h4"><a class="selflink" id="section-3.3.1" href="#section-3.3.1">3.3.1</a>.  Checks on Incoming Messages</span>

   When a message arrives at the Delivery Point, the system verifies:

   o  message type

   o  whether or not a PEC notification has to be returned.

<span class="h4"><a class="selflink" id="section-3.3.2" href="#section-3.3.2">3.3.2</a>.  Delivery PEC Notification</span>

   A delivery PEC notification is issued only after a correct PEC
   transport envelope (sections <a href="#section-2.2.2">2.2.2</a> and <a href="#section-3.1.5">3.1.5</a>) has been delivered to
   the recipient's mailbox.

   In all other cases (e.g., PEC anomaly envelopes, PEC notifications),
   the delivery PEC notification is not issued.  Regardless, the message
   received at the Delivery Point MUST be delivered to the recipient's
   mailbox unchanged.

   This notification tells the user that his/her message has been
   successfully delivered to the specified recipient.  It includes
   readable text that certifies the date and time of delivery, sender
   and receiver data, and the subject.  It also contains an XML
   certification data file and other optional parts for functionalities
   offered by the provider.

   The following fields are inserted in the header:

      X-Ricevuta: avvenuta-consegna
      Date: [delivery date]
      Subject: CONSEGNA: [original subject]
      From: posta-certificata@[mail domain]
      To: [original sender]
      X-Riferimento-Message-ID: [msgid]

   The value of the "X-TipoRicevuta:" header field in the PEC transport
   envelope is derived from the original message, thus allowing the
   sender to determine the type of delivery PEC notification requested
   from the primary recipients of the original message.  The
   notification MUST follow the format described in <a href="#section-4.3">section 4.3</a>.

<span class="h5"><a class="selflink" id="section-3.3.2.1" href="#section-3.3.2.1">3.3.2.1</a>.  Delivery PEC Notification: Complete</span>

   This is the default value for delivery PEC notifications.  When no
   value for "X-TipoRicevuta:" is specified, or when it contains the
   value "completa" (complete), the system will require a complete



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   delivery PEC notification from addressees in the "To:" field, while a
   concise PEC notification (<a href="#section-3.3.2.3">section 3.3.2.3</a>) will be required from
   those in the "Cc:" field.  The distinction between primary recipients
   and those in carbon copy is done through an analysis of the "To:" and
   "Cc:" fields.  For PEC notifications sent on behalf of primary
   recipients, a complete copy of the original message along with any
   attachments is inserted in the notification.  In case the system in
   charge of delivery is not able to determine the recipient type due to
   ambiguity problems in the "To:" and "Cc:" fields, delivery MUST be
   considered as if addressed to a primary recipient and include the
   complete copy of the original message.

   The notification body contains a readable text part that relates
   certification data according to the following model:

      Delivery PEC notification
      On [date] at [time] ([time zone]), the message "[subject]"
      originating from "[original sender]" and addressed to
      "[recipient]"
      was placed in the destination's mailbox.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file and added to
   the notification (<a href="#section-4.4">section 4.4</a>), along with any other parts that MAY
   be inserted by the provider for provider-specific services.  Parsing
   MUST be done on the XML part only.  The delivery PEC notification
   MUST be issued on behalf of every recipient of the message, and MUST
   follow the format described in <a href="#section-4.3">section 4.3</a>.

<span class="h5"><a class="selflink" id="section-3.3.2.2" href="#section-3.3.2.2">3.3.2.2</a>.  Delivery PEC Notification: Brief</span>

   In order to decrease the amount of data flowing, it is possible for
   the sender to ask for a delivery PEC notification in "brief" format.
   The brief delivery PEC notification contains the original message and
   a ciphered hash value for each of its parts.  The hash value SHOULD
   be calculated on base64 encoded parts.  As specified in <a href="#section-5.3">section 5.3</a>,
   PEC messages MUST transit only on machines that belong to the PEC
   network and that MUST NOT alter the encoding of the message during
   its transition/processing.

   NOTE: Even though PEC uses these relaxed specifications, PEC
   interoperability tests between over 20 service providers have never
   revealed any problems.  This is probably due to mail servers leaning
   more towards leaving the messages they receive intact without






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   applying any changes.  But issues might arise if a server decides to
   modify encoded parts; for example, change the base64 line length,
   whose hash value calculated at the receiver's end would then differ
   from that at the sender's side.

   To be able to verify the transmitted contents it is necessary for the
   sender to keep the unaltered original copy of the part(s) to which
   the hash values refer.

   If the PEC transport envelope contains the header:

        X-TipoRicevuta: breve

   the Delivery Point emits a brief delivery PEC notification on behalf
   of the primary recipients, and a concise one (<a href="#section-3.3.2.3">section 3.3.2.3</a>) on
   behalf of carbon copy recipients.  The value of the header field in
   the PEC transport envelope is derived from the original message.

   The notification body contains a readable text part according to a
   model that relates the following certification data:

      Brief delivery PEC notification
      On [date] at [time] ([time zone]), the message "[subject]"
      originating from "[original sender]" and addressed to
      "[recipient]"
      was placed in the destination's mailbox.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted in an XML file and added to
   the notification (<a href="#section-4.4">section 4.4</a>), along with other parts that MAY be
   included for specific provider-supplied services.  Parsing MUST be
   done on the XML part only.  The delivery PEC notification is issued
   on behalf of every recipient of the message, and MUST follow the
   format described in <a href="#section-4.3">section 4.3</a>.

   The MIME structure of the original message is unaltered as it is
   added to the notification, but each MIME part with a "name" parameter
   in the header field "Content-Type:" or a "filename" parameter in the
   header field "Content-Disposition:" MUST be substituted by a text
   file containing that MIME part's hash value.

   When the original message has an S/MIME format, it is necessary not
   to alter the integrity of the message structure.  Verification of the
   S/MIME part in the original message takes place when the MIME type of
   the top-level entity (which coincides with the message itself) is
   checked.  An S/MIME message MAY have the following MIME types (as per
   [<a href="#ref-SMIMEV3" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification&quot;">SMIMEV3</a>]):



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   o  multipart/signed

      Represents an original message signed by the sender using the
      structure described in [<a href="#ref-MIME-SECURE" title="&quot;Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted&quot;">MIME-SECURE</a>].  The message is made up of
      two MIME parts: the first is the message itself before the
      application of the sender's signature, whereas the second contains
      signature data.  The second part (generally of type
      "application/pkcs7-signature" or "application/x-pkcs-signature")
      contains data added during the signing phase and MUST be left
      unchanged to avoid compromising the overall message structure;

   o  "application/pkcs7-mime" or "application/x-pkcs7-mime"

      The message is composed of a sole CMS object within the MIME part.
      Given that attachments cannot be separated from the CMS object,
      the MIME part is left intact (i.e., it is not replaced by the hash
      value); therefore, the brief PEC notification is the same as the
      complete PEC notification.

   If the original message contains parts whose "Content-Type:" is
   "message/rfc822", i.e., contains an email message as attachment, the
   entire attached message is substituted with its corresponding hash
   value.

   Therefore, when emitting a brief delivery PEC notification, the
   provider MUST:

   1. identify and extract all the parts from the first MIME part of the
     multipart/signed S/MIME message;

   2. calculate the hash values of all the files attached by the sender
     to the original message;

   3. substitute originals with their hash values.

   In general, in the case of original messages in S/MIME format, the
   copy of the message inserted within the brief delivery PEC
   notification will have the following characteristics:

   o  if the original message is signed, the S/MIME structure and
      signature-relative data will remain unchanged.  The message will
      generate an error in a future signature integrity verification
      phase following the substitution of attachments with the
      corresponding hash values.

   o  if the original message contains the "application/pkcs7-mime" or
      "application/x-pkcs7-mime" MIME type, attachments present in the
      message will not be substituted by their hash values, due to



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      impossibility of identification within a CMS structure.  The
      content of the brief delivery PEC notification will coincide with
      that of a normal delivery PEC notification.

   The algorithm used for hash calculation is the [<a href="#ref-SHA1" title="&quot;US Secure Hash Algorithm 1 (SHA1)&quot;">SHA1</a>], calculated on
   the entire content of the part.  To allow distinction between hash
   files and the files to which they refer, the suffix ".hash" is added
   to the original filename.  The hash value is written in the file
   using a hexadecimal representation as a single sequence of 40
   characters.  The MIME type of these attachments is set to
   "text/plain" to highlight their textual nature.

<span class="h5"><a class="selflink" id="section-3.3.2.3" href="#section-3.3.2.3">3.3.2.3</a>.  Delivery PEC Notification: Concise</span>

   If the PEC transport envelope contains the header:

        X-TipoRicevuta: sintetica

   the Delivery Point emits, both to primary and carbon copy recipients,
   a concise delivery PEC notification that does not contain the
   original message.

   The message body of the notification contains a readable text part
   according to a model that relates the following certification data:

      Concise delivery PEC notification
      On [date] at [time] ([time zone]), the message "[subject]"
      originating from "[original sender]" and addressed to
      "[recipient]"
      was placed in the destination's mailbox.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted within an XML file and added
   to the notification (<a href="#section-4.4">section 4.4</a>), along with additional parts that
   MAY be included for provider-specific services.  Parsing MUST be done
   on the XML part only.  The notification is sent to each one of the
   recipients to whom the message is delivered, and MUST follow the
   format described in <a href="#section-4.3">section 4.3</a>.

   The concise delivery PEC notification follows the same emission rules
   as the delivery PEC notification; added to it is only the XML file
   containing the certification data, not the original message.








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<span class="h4"><a class="selflink" id="section-3.3.3" href="#section-3.3.3">3.3.3</a>.  Non-Delivery PEC Notification</span>

   If an error occurs during the delivery of a correct PEC transport
   message, the system returns to the sender a non-delivery PEC
   notification that indicates the error condition.

   The header will contain the following fields:

      X-Ricevuta: errore-consegna
      Date: [date of notification emission]
      Subject: AVVISO DI MANCATA CONSEGNA: [original subject]
      From: posta-certificata@[mail domain]
      To: [original sender]
      X-Riferimento-Message-ID: [msgid]

   The notification body contains a readable text part according to a
   model that relates the following data:

      Non-delivery PEC notification
      On [date] at [time] ([time zone]), in the message "[subject]"
      originating from "[original sender]" and addressed to
      "[recipient]"
      an error was detected [brief error description].
      The message was refused by the system.
      Message identifier: [PEC msgid of corresponding
      PEC transport envelope]

   The same certification data is inserted within an XML file and added
   to the notification in order to allow for automatic checks (<a href="#section-4.4">section</a>
   <a href="#section-4.4">4.4</a>).  Parsing MUST be done on the XML part only.  Additional parts
   MAY be included by the PEC provider for provider-specific services.
   The notification MUST follow the format described in <a href="#section-4.3">section 4.3</a>.

<span class="h3"><a class="selflink" id="section-3.4" href="#section-3.4">3.4</a>.  Sender and Receiver Belonging to the Same Domain</span>

   PEC messages MUST be processed even if both sender and receiver(s)
   belong to the same PEC domain.

<span class="h3"><a class="selflink" id="section-3.5" href="#section-3.5">3.5</a>.  Example: Complete Transaction between Two PEC Domains</span>

   A correct transaction between two PEC domains goes through the
   following steps:

   o  The sending user sends an email to his provider's Access Point;

   o  The Access Point runs all checks and emits a server-user
      acceptance PEC notification to the user;




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   o  The Access Point creates a PEC transport envelope and forwards it
      to the Incoming Point of the receiving provider;

   o  The receiver's Incoming Point verifies the PEC transport envelope
      and creates a server-server acceptance PEC notification to be sent
      to the sending provider;

   o  The sender's Incoming Point verifies the validity of the server-
      server acceptance PEC notification and forwards it to the Delivery
      Point;

   o  The sender's Delivery Point saves the server-server acceptance PEC
      notification in the provider's service mailbox;

   o  The receiver's Incoming Point forwards the PEC transport envelope
      to the receiver's Delivery Point;

   o  The receiver's Delivery Point verifies the contents of the PEC
      transport envelope and saves it in the recipient's mailbox;

   o  The receiver's Delivery Point creates a delivery PEC notification
      and sends it to the sender's Incoming Point;

   o  The sender's Incoming Point verifies the validity of the delivery
      PEC notification and forwards it to the sender's Delivery Point;

   o  The sender's Delivery Point saves the delivery PEC notification in
      the sending user's mailbox;

   o  The receiving user has the message at his disposition.

   NOTE: Some of these steps might occur in parallel, thus the
   interaction might complete in a different order.

<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>.  Formats</span>

<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>.  Temporal Reference</span>

   For all operations carried out during message, notification, and log
   elaboration processes by the Access, Incoming, and Delivery Points,
   it is necessary to have an accurate temporal reference available.
   All events (generation of PEC notifications, transport envelopes,
   logs, etc.) that constitute the transaction of message elaboration at
   the Access, Incoming, and Delivery Points MUST employ a sole temporal
   value obtained from within the transaction itself.






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   Doing this renders the instant of message elaboration unambiguous
   within PEC logs, notifications, messages, etc., generated by the
   server.

<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>.  User Date/Time</span>

   Temporal indications supplied by the service in readable format (text
   in PEC notifications, transport envelopes, etc.) are provided with
   reference to the legal time at the moment of the operation.
   Following is the specification using the syntax description notation
   defined in [<a href="#ref-ABNF" title="&quot;Augmented BNF for Syntax Specifications: ABNF&quot;">ABNF</a>].

   date-fullyear   = 4DIGIT
   date-month      = 2DIGIT  ; 01-12
   date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
                             ; month/year
   time-hour       = 2DIGIT  ; 00-23
   time-minute     = 2DIGIT  ; 00-59
   time-second     = 2DIGIT  ; 00-58, 00-59, 00-60 based on leap second
                             ; rules

   time-offset     = "(" ("+" / "-") time-hour ":" time-minute ")"

   partial-time    = time-hour ":" time-minute ":" time-second

   full-date       = date-mday "/" date-month "/" date-fullyear
   full-time       = partial-time time-offset

   NOTE: For number of days in a month, leap year, and leap second
         restrictions see section 5.7 of [<a href="#ref-TIMESTAMP" title="&quot;Date and Time on the Internet: Timestamps&quot;">TIMESTAMP</a>].

<span class="h3"><a class="selflink" id="section-4.3" href="#section-4.3">4.3</a>.  Format of a PEC Message Body</span>

   This section describes the characteristics of the various components
   of PEC messages and notifications generated by a PEC system.  If one
   of the message parts contains characters with values outside of the
   range 0-127 (7-bit ASCII), that part will have to be adequately
   encoded so that 7-bit transportation compatibility is guaranteed
   (e.g., quoted-printable, base64 as per [<a href="#ref-MIME1" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies&quot;">MIME1</a>]).

   Before applying the signature, the message body has Content-Type:
   multipart/mixed.  Each part is described in the sections below.  The
   first part is the user readable text generated by the PEC system,
   while the second and third parts are interchangeable in order and
   contain the original message and the XML file for the certification
   data.





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<span class="h4"><a class="selflink" id="section-4.3.1" href="#section-4.3.1">4.3.1</a>.  User Readable Text</span>

   Character set: ISO-8859-1 (Latin-1)
   MIME type: text/plain or multipart/alternative

   The multipart/alternative MIME type MAY be used to add an HTML
   version of the body of system-generated messages.  In this case, two
   sub-parts MUST be present: one of type text/plain, the other
   text/html.  For the HTML part:

   o  it MUST contain the same information as related in the text part;

   o  it MUST NOT contain references to elements (e.g., images, sounds,
      font, style sheets), neither internal to the message (added MIME
      parts) nor external (e.g., hosted on the provider's server);

   o  it MUST NOT have active content (e.g., JavaScript, VBscript, Plug-
      in, ActiveX).

<span class="h4"><a class="selflink" id="section-4.3.2" href="#section-4.3.2">4.3.2</a>.  Original Message</span>

   MIME type: message/rfc822
   Attachment name: postacert.eml

<span class="h4"><a class="selflink" id="section-4.3.3" href="#section-4.3.3">4.3.3</a>.  Certification Data</span>

   Character set: UTF-8
   MIME type: application/xml
   Attachment name: certdata.xml

<span class="h3"><a class="selflink" id="section-4.4" href="#section-4.4">4.4</a>.  Certification Data Scheme</span>

   Following is the DTD relative to the [<a href="#ref-XML" title="&quot;Extensible Markup Language (XML) 1.0 (Fifth Edition)&quot;">XML</a>] file that contains
   certification data attached to PEC notifications.

   &lt;!--Use the element "postacert" as root--&gt;
   &lt;!--"tipo" indicates the typology of the PEC message--&gt;
   &lt;!--The attribute "errore" can have the following values--&gt;
   &lt;!--"nessuno" = no error--&gt;
   &lt;!--"no-dest" (with type="errore-consegna") = --&gt;
   &lt;!--                                        wrong recipient--&gt;
   &lt;!--"no-dominio" (with type="errore-consegna") = --&gt;
   &lt;!--                                           wrong domain--&gt;
   &lt;!--"virus" (with type="errore-consegna") = virus--&gt;
   &lt;!--"virus" (with type="non-accettazione") = virus--&gt;
   &lt;!--"altro" = generic error--&gt;
   &lt;!ELEMENT postacert (intestazione, dati)&gt;
   &lt;!ATTLIST postacert



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         tipo (accettazione |
               non-accettazione |
               presa-in-carico |
               avvenuta-consegna |
               posta-certificata |
               errore-consegna |
               preavviso-errore-consegna |
               rilevazione-virus) #REQUIRED
         errore (nessuno |
                 no-dest |
                 no-dominio |
                 virus |
                 altro) "nessuno"&gt;

   &lt;!--Header of the original message--&gt;
   &lt;!ELEMENT intestazione (mittente,
                           destinatari+,
                           risposte,
                           oggetto?)&gt;

   &lt;!--Sender ("From:" field) of the original message--&gt;
   &lt;!ELEMENT mittente (#PCDATA)&gt;

   &lt;!--Complete list of recipients ("To:" and "Cc:" fields)--&gt;
   &lt;!--of the original message--&gt;
   &lt;!--"tipo" indicates the typology of the recipient--&gt;
   &lt;!ELEMENT destinatari (#PCDATA)&gt;
   &lt;!ATTLIST destinatari
         tipo (certificato | esterno) "certificato"&gt;

   &lt;!--Value of the "Reply-To:" field of the original message--&gt;
   &lt;!ELEMENT risposte (#PCDATA)&gt;
   &lt;!--Value of the "Subject:" field of the original message--&gt;
   &lt;!ELEMENT oggetto (#PCDATA)&gt;

   &lt;!--PEC message data--&gt;
   &lt;!ELEMENT dati (gestore-emittente,
                   data,
                   identificativo,
                   msgid?,
                   ricevuta?,
                   consegna?,
                   ricezione*,
                   errore-esteso?)&gt;

   &lt;!--Descriptive string of the provider that certifies --&gt;
   &lt;!--the data--&gt;
   &lt;!ELEMENT gestore-emittente (#PCDATA)&gt;



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   &lt;!--Date/time of message elaboration--&gt;
   &lt;!--"zona" is the difference between local time and UTC in --&gt;
   &lt;!--"[+|-]hhmm" format--&gt;
   &lt;!ELEMENT data (giorno, ora)&gt;
   &lt;!ATTLIST data
         zona CDATA #REQUIRED&gt;

   &lt;!--Day in "dd/mm/yyyy" format--&gt;
   &lt;!ELEMENT giorno (#PCDATA)&gt;
   &lt;!--Local hour in "hh:mm:ss" format--&gt;
   &lt;!ELEMENT ora (#PCDATA)&gt;

   &lt;!--PEC msgid--&gt;
   &lt;!ELEMENT identificativo (#PCDATA)&gt;

   &lt;!--msgid of the original message before modifications--&gt;
   &lt;!ELEMENT msgid (#PCDATA)&gt;

   &lt;!--For PEC transport envelopes and delivery notifications--&gt;
   &lt;!--indicate the type of PEC notification requested by the--&gt;
   &lt;!--sender--&gt;
   &lt;!ELEMENT ricevuta EMPTY&gt;
   &lt;!ATTLIST ricevuta
         tipo (completa |
               breve   |
               sintetica ) #REQUIRED&gt;

   &lt;!--For delivery, non-delivery, virus-induced non-delivery, --&gt;
   &lt;!-- virus detection, and timeout PEC notifications--&gt;
   &lt;!--Recipient address to which delivery has been carried --&gt;
   &lt;!--out/tried--&gt;
   &lt;!ELEMENT consegna (#PCDATA)&gt;
   &lt;!--For server-server acceptance PEC notifications--&gt;
   &lt;!--recipients for whom it is the relative PEC notification--&gt;
   &lt;!ELEMENT ricezione (#PCDATA)&gt;

   &lt;!--In case of error--&gt;
   &lt;!--brief description of the error--&gt;
   &lt;!ELEMENT errore-esteso (#PCDATA)&gt;

<span class="h3"><a class="selflink" id="section-4.5" href="#section-4.5">4.5</a>.  PEC Providers Directory Scheme</span>

   The PEC providers directory is created through a centralized LDAP
   server that contains the providers' data and their corresponding PEC
   mail domains.






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   The following are the directory scheme's attributes:

   - providerCertificateHash: hash of provider's certificate

   - providerCertificate: provider certificate

   - providerName: provider name

   - mailReceipt: provider reception email address

   - managedDomains: managed domains

   - LDIFLocationURL: provider LDIF record URL

   - providerUnit: secondary operating environment name

   The directory's base root is "o=postacert" and the
   "DistinguishedName" of single records is of the type
   "&lt;providerName=&lt;name&gt;,o=postacert&gt;".  Search within the directory is
   carried out mainly in case-sensitive mode using the
   "providerCertificateHash" attribute (during envelope signature
   verification phase) or the "managedDomains" attribute (during message
   acceptance phase).  It is possible for the record of a single
   provider to contain multiple "providerCertificate" attributes with
   the related "providerCertificateHash" attributes in order to allow
   the handling of the renewal of expiring certificates.  The provider
   MUST make sure to update its record with sufficient advance before
   the certificate expiration date, by adding a new certificate whose
   validity overlaps that of the previous one.

   The data of all PEC providers is encompassed in a [<a href="#ref-LDIF" title="&quot;The LDAP Data Interchange Format (LDIF) - Technical Specification&quot;">LDIF</a>] file, which
   is available as an [<a href="#ref-HTTPS" title="&quot;HTTP Over TLS&quot;">HTTPS</a>] object and can be found at the URL to
   which the 'LDIFLocationURL' attribute in the "dn: o=postacert" record
   points (see <a href="#section-4.5.6">section 4.5.6</a>).  To guarantee authenticity, that file
   MUST be signed by the provider for the operations regarding its PEC
   services using the method described for single providers.  The file,
   the signature, and the X.509v3 certificate MUST be inserted in a
   PKCS#7 structure in binary ASN.1 DER format as a file with ".p7m"
   extension.  The centralized [<a href="#ref-LDAP" title="&quot;Lightweight Directory Access Protocol (LDAP): Technical Specification Road Map&quot;">LDAP</a>] system downloads that file on a
   daily basis and, after suitable verifications of the signature,
   applies it to the provider's record.

   Through the [<a href="#ref-LDIF" title="&quot;The LDAP Data Interchange Format (LDIF) - Technical Specification&quot;">LDIF</a>] file, single providers MUST keep a copy of the
   directory locally, updated on a daily basis, in order to improve
   system performance by avoiding continuous request dispatches to the
   central system for every message elaboration phase.





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   If secondary environments are present, the [<a href="#ref-LDIF" title="&quot;The LDAP Data Interchange Format (LDIF) - Technical Specification&quot;">LDIF</a>] file indicated in
   the main environment's record MUST relate the contents of all the
   provider-relevant records.

      NOTE: This specification uses an unregistered LDAP DN name space
            that may lead to conflict with other registered or
            unregistered names.

<span class="h4"><a class="selflink" id="section-4.5.1" href="#section-4.5.1">4.5.1</a>.  providerCertificateHash Attribute</span>

   The 'providerCertificateHash' attribute is a hexadecimal
   representation of the hash in SHA1 format of the X.509v3 certificate
   used by the provider for PEC notifications and envelope signatures.

   ( 1.3.6.1.4.1.16572.2.2.1  NAME 'providerCertificateHash'
     DESC 'Hash SHA1 of X.509 certificate in hexadecimal format'
     EQUALITY caseIgnoreIA5Match
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

   The IA5String ( 1.3.6.1.4.1.1466.115.121.1.26 ) syntax is defined in
   [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

<span class="h4"><a class="selflink" id="section-4.5.2" href="#section-4.5.2">4.5.2</a>.  providerCertificate Attribute</span>

   The 'providerCertificate' attribute holds a set of certificate(s)
   used by the provider to sign PEC notifications and transport
   envelopes.

   ( 1.3.6.1.4.1.16572.2.2.2  NAME 'providerCertificate'
     DESC 'X.509 certificate in ASN.1 DER binary format'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.8 )

   The Certificate syntax ( 1.3.6.1.4.1.1466.115.121.1.8 ) is defined in
   [<a href="./rfc4523" title="&quot;Lightweight Directory Access Protocol (LDAP) Schema Definitions for X.509 Certificates&quot;">RFC4523</a>].

   As required by this attribute type's syntax, values of this attribute
   are requested and transferred using the attribute description
   "providerCertificate;binary" [<a href="./rfc4522" title="&quot;Lightweight Directory Access Protocol (LDAP): The Binary Encoding Option&quot;">RFC4522</a>].

<span class="h4"><a class="selflink" id="section-4.5.3" href="#section-4.5.3">4.5.3</a>.  providerName Attribute</span>

   The 'providerName' attribute contains the name of the PEC provider.
   All records MUST contain their provider's name in this attribute.








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   ( 1.3.6.1.4.1.16572.2.2.3  NAME 'providerName'
     DESC 'PEC provider name'
     EQUALITY caseIgnoreMatch
     SUBSTR caseIgnoreSubstringsMatch
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
     SINGLE-VALUE )

   The Directory String ( 1.3.6.1.4.1.1466.115.121.1.15 ) syntax is
   defined in [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

<span class="h4"><a class="selflink" id="section-4.5.4" href="#section-4.5.4">4.5.4</a>.  mailReceipt Attribute</span>

   The 'mailReceipt' attribute contains the provider's email address
   within the provider to which server-server acceptance and virus
   detection PEC notifications are sent.  This address is a limited
   version of the addr-spec construct described in [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] (without
   angle brackets); it only permits the dot-atom-text form on both the
   left- and right-hand sides of the "@", and does not have internal
   CFWS.

   ( 1.3.6.1.4.1.16572.2.2.4 NAME 'mailReceipt'
     DESC 'E-mail address of the service mailbox'
     EQUALITY caseIgnoreIA5Match
     SUBSTR caseIgnoreIA5SubstringsMatch
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.26
     SINGLE-VALUE )

   The IA5String ( 1.3.6.1.4.1.1466.115.121.1.26 ) syntax is defined in
   [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

<span class="h4"><a class="selflink" id="section-4.5.5" href="#section-4.5.5">4.5.5</a>.  managedDomains Attribute</span>

   The 'managedDomains' attribute holds a set of domains [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>] that are
   handled by a PEC provider.  Domains are limited to dot-atom form
   ([<a href="./rfc1034" title="&quot;Domain names - concepts and facilities&quot;">RFC1034</a>], [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]).

   ( 1.3.6.1.4.1.16572.2.2.5 NAME 'managedDomains'
     DESC 'Domains handled by the PEC provider'
     EQUALITY caseIgnoreIA5Match
     SUBSTR caseIgnoreIA5SubstringsMatch
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

   The IA5String ( 1.3.6.1.4.1.1466.115.121.26 ) syntax is defined in
   [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

   The 'managedDomains' attribute holds a set of domains [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>] that are
   handled by a PEC provider.  Domains are limited to dot-atom form
   ([<a href="./rfc1034" title="&quot;Domain names - concepts and facilities&quot;">RFC1034</a>], [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]).



<span class="grey">Petrucci, et al.              Informational                    [Page 42]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-43" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


<span class="h4"><a class="selflink" id="section-4.5.6" href="#section-4.5.6">4.5.6</a>.  LDIFLocationURL Attribute</span>

   The 'LDIFLocationURL' attribute contains an [<a href="#ref-HTTPS" title="&quot;HTTP Over TLS&quot;">HTTPS</a>] URL that points
   to the location of the [<a href="#ref-LDIF" title="&quot;The LDAP Data Interchange Format (LDIF) - Technical Specification&quot;">LDIF</a>] file defining the provider's record.
   When the attribute is present in the record "dn: o=postacert", then
   it contains the definition of the entire directory in [<a href="#ref-LDIF" title="&quot;The LDAP Data Interchange Format (LDIF) - Technical Specification&quot;">LDIF</a>] format.
   The LDIF file will have a MIME type of application/pkcs7-mime, with
   the parameter smime-type/signed-data.  [<a href="#ref-SMIMEV3" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification&quot;">SMIMEV3</a>] The LDIF file is
   encoded using the UTF-8 character set.

   Secondary environment records MUST NOT contain the 'LDIFLocationURL'
   attribute which is obtained from the main environment's attributes
   for all records connected to the provider.

   ( 1.3.6.1.4.1.16572.2.2.6 NAME 'LDIFLocationURL'
     DESC 'URL of the LDIF file that defines the entry'
     EQUALITY caseExactMatch
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
     SINGLE-VALUE )

   The Directory String ( 1.3.6.1.4.1.1466.115.121.1.15 ) syntax is
   defined in [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

<span class="h4"><a class="selflink" id="section-4.5.7" href="#section-4.5.7">4.5.7</a>.  providerUnit Attribute</span>

   The 'providerUnit' attribute contains the name of secondary operating
   environments -- an attribute not present for the main environment.
   It is possible for the provider to define several distinct records,
   each indicating a single, different, secondary operating environment,
   for which it is possible to declare specific attributes that are, if
   need be, distinct from those relative to the main and other
   environments.

   The "DistinguishedName" of the records relative to the secondary
   operating environments are of the type
   "&lt;providerUnits=&lt;environment&gt;,providerName=&lt;name&gt;,o=postacert&gt;".
   Every provider MUST have a record associated to its own main
   environment, distinguishable for the absence of the "providerUnit"
   attribute within the record and the DistinguishedName.

   ( 1.3.6.1.4.1.16572.2.2.7 NAME 'providerUnit'
     DESC 'Name of the secondary operative environment'
     EQUALITY caseIgnoreMatch
     SUBSTR caseIgnoreSubstringsMatch
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
     SINGLE-VALUE )





<span class="grey">Petrucci, et al.              Informational                    [Page 43]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-44" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


   The Directory String ( 1.3.6.1.4.1.1466.115.121.1.15 ) syntax is
   defined in [<a href="#ref-LDAP-SYNTAXES" title="&quot;Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules&quot;">LDAP-SYNTAXES</a>].

<span class="h4"><a class="selflink" id="section-4.5.8" href="#section-4.5.8">4.5.8</a>.  LDIFLocationURLObject Object Class</span>

   The schema definition of the 'LDIFLocationURLObject' object class:

   ( 1.3.6.1.4.1.16572.2.1.1 NAME 'LDIFLocationURLObject'
     SUP top AUXILIARY
     MAY ( LDIFLocationURL ) )

<span class="h4"><a class="selflink" id="section-4.5.9" href="#section-4.5.9">4.5.9</a>.  Provider Object Class</span>

   The schema definition of the 'provider' object class:

   ( 1.3.6.1.4.1.16572.2.1.2 NAME 'provider'
     SUP top STRUCTURAL
     MUST ( providerCertificateHash
            providerCertificate
            providerName
            mailReceipt
            managedDomains )

     MAY ( description
           LDIFLocationURL
           providerUnit )

<span class="h4"><a class="selflink" id="section-4.5.10" href="#section-4.5.10">4.5.10</a>.  LDIF File Example</span>

   The following LDIF file represents an example of a providers'
   directory, containing a base root and two fictitious providers.  The
   inserted certificates are two self-signed certificates used for
   example purposes only:

       dn: o=postacert
       objectclass: top
       objectclass: organization
       objectClass: LDIFLocationURLObject
       o: postacert
       LDIFLocationURL: <a href="https://igpec.rupa.example.com/igpec.ldif.p7m">https://igpec.rupa.example.com/igpec.ldif.p7m</a>
       description: Base root for the PEC providers directory
       dn: providerName=Anonymous Certified Mail S.p.A.,o=postacert
       objectclass: top
       objectclass: provider
       providerName: Anonymous Certified Mail S.p.A.
       providerCertificateHash:
        7E7AEF1059AE0F454F2643A95F69EC3556009239
       providerCertificate;binary::



<span class="grey">Petrucci, et al.              Informational                    [Page 44]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-45" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


        MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
        JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
        QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
        J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
        A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
        EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
        bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
        KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
        2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
        alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
        wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
        SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
        AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
        5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
        cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
        Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
        XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9
        5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
       mailReceipt: ssacceptance@postalser.example.com
       LDIFLocationURL: https://anpocert.example.com/anpocert.ldif.p7m
       managedDomains: mail.anpocert.example.com
       managedDomains: cert.company.example.com
       managedDomains: costmec.example.com
       description: Certified mail services for companies

       dn: providerName=Postal Services S.p.A,o=postacert
       objectclass: top
       objectclass: provider
       providerName: Postal Services S.p.A
       providerCertificateHash:
        e00fdd9d88be0e2cc766b893315caf93d5701a6a
       providerCertificate;binary::
        MIIDHjCCAoegAwIBAgIBADANBgkqhkiG9w0BAQQFADBuMQswCQYDVQQGEw
        JJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIFMuci5sLjEPMA0GA1UE
        CxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0YS1jZXJ0aWZpY2F0YU
        BzZXJwb3N0YWwuaXQwHhcNMDIxMjA5MTczMjE2WhcNMDMxMjA5MTczMjE2
        WjBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIF
        Muci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0
        YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXQwgZ8wDQYJKoZIhvcNAQEBBQ
        ADgY0AMIGJAoGBAKoc7n6zA+sO8NATMcfJ+U2aoDEsrj/cObG3QAN6Sr+l
        ygWxYXLBZNfSDWqL1K4edLr4gCZIDFsq0PIEaYZhYRGjhbcuJ9H/ZdtWdX
        xcwEWN4mwFzlsASogsh5JeqS8db3A1JWkvhO9EUfaCYk8YMAkXYdCtLD9s
        9tCYZeTE2ut9AgMBAAGjgcswgcgwHQYDVR0OBBYEFHPw7VJIoIM3VYhuHa
        eAwpPF5leMMIGYBgNVHSMEgZAwgY2AFHPw7VJIoIM3VYhuHaeAwpPF5leM
        oXKkcDBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YW
        xpIFMuci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5w
        b3N0YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXSCAQAwDAYDVR0TBAUwAw
        EB/zANBgkqhkiG9w0BAQQFAAOBgQApqeXvmOyEjwhMrXezPAXELMZwv4qq



<span class="grey">Petrucci, et al.              Informational                    [Page 45]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-46" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


        r5ri4XuxTq6sS9jRsEbZrS+NmbcJ7S7eFwNQMNxYFVJqdWoLh8qExsTLXn
        sKycSnHbCfuphrKvXjQvR2da75U4zGSkroiyvJ2s9TtiCcT3lQtIjmvrFb
        aSBiyzj+za7foFUCQmxCLtDaA==
       mailReceipt: takecharge@postalser.example.com
       LDIFLocationURL: https://postalser.example.com/ldif.txt.p7m
       managedDomains: postal-services.example.com
       managedDomains: receivedmail.example.com
       description: Certified mail services for the public

   The following LDIF file represents an example of a PEC providers'
   directory, containing a base root and two fictitious providers, the
   first of which handles a secondary environment as well.  The
   certificates inserted are two self-signed certificates used for
   example purposes only:

       dn: o=postacert
       objectclass: top
       objectclass: organization
       objectClass: LDIFLocationURLObject
       o: postacert
       LDIFLocationURL: <a href="https://igpec.rupa.example.com/igpec.ldif.p7m">https://igpec.rupa.example.com/igpec.ldif.p7m</a>
       description: Base root for the PEC providers directory

       dn: providerName=Anonymous Certified Mail S.p.A.,o=postacert
       objectclass: top
       objectclass: provider
       providerName: Anonymous Certified Mail S.p.A.

       providerCertificateHash:
        7E7AEF1059AE0F454F2643A95F69EC3556009239
       providerCertificate;binary::
        MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
        JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
        QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
        J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
        A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
        EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
        bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
        KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
        2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
        alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
        wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
        SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
        AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
        5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
        cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
        Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
        XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9



<span class="grey">Petrucci, et al.              Informational                    [Page 46]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-47" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


        5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
       mailReceipt: notifications@anpocert.it.example
       LDIFLocationURL: http://anpocert.example.com/anpocert.ldif.p7m
       managedDomains: mail.anpocert.example.com
       managedDomains: cert.company.example.com
       managedDomains: costmec.example.com
       description: Certified mail services for companies
       dn: providerUnit=Secondary Environment, providerName=Anonymous
        Certified Mail S.p.A.,o=postacert
       objectclass: top
       objectclass: provider
       providerName: Certified Mail S.p.A.
       providerUnit: Secondary Environment
       providerCertificateHash:
        7E7AEF1059AE0F454F2643A95F69EC3556009239
       providerCertificate;binary::
        MIIDBjCCAm+gAwIBAgIBADANBgkqhkiG9w0BAQQFADBmMQswCQYDVQQGEw
        JJVDEpMCcGA1UEChMgQW5vbmltYSBQb3N0YSBDZXJ0aWZpY2F0YSBTLnAu
        QS4xLDAqBgkqhkiG9w0BCQEWHXBvc3RhLWNlcnRpZmljYXRhQGFucG9jZX
        J0Lml0MB4XDTAyMTIwOTE3MjQxNVoXDTAzMTIwOTE3MjQxNVowZjELMAkG
        A1UEBhMCSVQxKTAnBgNVBAoTIEFub25pbWEgUG9zdGEgQ2VydGlmaWNhdG
        EgUy5wLkEuMSwwKgYJKoZIhvcNAQkBFh1wb3N0YS1jZXJ0aWZpY2F0YUBh
        bnBvY2VydC5pdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr8J+qK
        KdxV9LzDMPqwnEy0P8H/KwbI0Szs8p6UZajZdpeUK0Ncbrv1QyXZNNtSMC
        2uL09HDyx8agjgZWdhypnehguiSK3busha15RSpMGhiqxmz2b0HhOG73Gf
        alZelqrwqmElna4MNUaLhbOvTd/sqPUS378w5IaIhWxzy34XcCAwEAAaOB
        wzCBwDAdBgNVHQ4EFgQUN8lC0znQWEs0xspZ/aBzsaGvRZMwgZAGA1UdIw
        SBiDCBhYAUN8lC0znQWEs0xspZ/aBzsaGvRZOhaqRoMGYxCzAJBgNVBAYT
        AklUMSkwJwYDVQQKEyBBbm9uaW1hIFBvc3RhIENlcnRpZmljYXRhIFMucC
        5BLjEsMCoGCSqGSIb3DQEJARYdcG9zdGEtY2VydGlmaWNhdGFAYW5wb2Nl
        cnQuaXSCAQAwDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQQFAAOBgQA58B
        Z+q1qSKpuffzTBpMtbeFkDIxMqMa+ycnxdMNvcWgCm1A9ZiFJsvqYhDDqA
        XxfHjkrzXuSZkYq6WiQCsLp0aYVy40QCIwbOunhrvsxh3vsG5CgN76JzZ9
        5Z/1OCFNhLfqf1VH2NSS8TaYCCi/VO7W1Q1KkcA2VlxlQP7McSUw==
       mailReceipt: notifications@secondary.anpocert.example.com
       managedDomains: management.anpocert.example.com
       managedDomains: personnel.anpocert.example.com
       description: Corporate internal services
       dn: providerName=Postal Services S.r.l.,o=postacert
       objectclass: top
       objectclass: provider
       providerName: Postal Services S.r.l.
       providerCertificateHash:
        e00fdd9d88be0e2cc766b893315caf93d5701a6a
       providerCertificate;binary::
        MIIDHjCCAoegAwIBAgIBADANBgkqhkiG9w0BAQQFADBuMQswCQYDVQQGEw
        JJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIFMuci5sLjEPMA0GA1UE
        CxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0YS1jZXJ0aWZpY2F0YU



<span class="grey">Petrucci, et al.              Informational                    [Page 47]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-48" ></span>
<span class="grey"><a href="./rfc6109">RFC 6109</a>                Certified Electronic Mail             April 2011</span>


        BzZXJwb3N0YWwuaXQwHhcNMDIxMjA5MTczMjE2WhcNMDMxMjA5MTczMjE2
        WjBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YWxpIF
        Muci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5wb3N0
        YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXQwgZ8wDQYJKoZIhvcNAQEBBQ
        ADgY0AMIGJAoGBAKoc7n6zA+sO8NATMcfJ+U2aoDEsrj/cObG3QAN6Sr+l
        ygWxYXLBZNfSDWqL1K4edLr4gCZIDFsq0PIEaYZhYRGjhbcuJ9H/ZdtWdX
        xcwEWN4mwFzlsASogsh5JeqS8db3A1JWkvhO9EUfaCYk8YMAkXYdCtLD9s
        9tCYZeTE2ut9AgMBAAGjgcswgcgwHQYDVR0OBBYEFHPw7VJIoIM3VYhuHa
        eAwpPF5leMMIGYBgNVHSMEgZAwgY2AFHPw7VJIoIM3VYhuHaeAwpPF5leM
        oXKkcDBuMQswCQYDVQQGEwJJVDEfMB0GA1UEChMWU2Vydml6aSBQb3N0YW
        xpIFMuci5sLjEPMA0GA1UECxMGRC5DLkMuMS0wKwYJKoZIhvcNAQkBFh5w
        b3N0YS1jZXJ0aWZpY2F0YUBzZXJwb3N0YWwuaXSCAQAwDAYDVR0TBAUwAw
        EB/zANBgkqhkiG9w0BAQQFAAOBgQApqeXvmOyEjwhMrXezPAXELMZwv4qq
        r5ri4XuxTq6sS9jRsEbZrS+NmbcJ7S7eFwNQMNxYFVJqdWoLh8qExsTLXn
        sKycPSnHbCfuphrKvXjQvR2da75U4zGSkroiyvJ2s9TtiCcT3lQtIjmvrF
        baSBiyzj+za7foFUCQmxCLtDaA==
       mailReceipt: ssacceptance@postalser.example.com
       LDIFLocationURL: http://postalser.example.com/ldif.txt.p7m
       managedDomains: postal-services.example.com
       managedDomains: receivedmail.example.com
       description: Certified mail services for the public

<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>.  Security-Related Aspects</span>

<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>.  Digital Signature</span>

   It is recommended that a dedicated hardware module be used to handle
   private key and signature operations, the specifications of which are
   outside the scope of this document.  It's up to the PEC providers to
   conform to security requisites expected for the service.

<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>.  Authentication</span>

   User access to PEC services through the Access Point MUST be allowed
   only upon successful user authentication on the system.

   For example, authentication might use user-ID and password, or, if
   available and considered necessary for the type of service provided,
   an electronic ID card or the national services card.  Choice of
   authentication method is left to the better judgment of the service
   provider.  Authentication is necessary to guarantee as much as
   possible that the message is sent by a PEC user whose identification
   data is congruent with the specified sender, so as to avoid
   falsification of the latter.







<span class="grey">Petrucci, et al.              Informational                    [Page 48]</span></pre>
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<span class="h3"><a class="selflink" id="section-5.3" href="#section-5.3">5.3</a>.  Secure Interaction</span>

   To guarantee that the original message remains unaltered during
   transaction, envelopment and signature are applied on outgoing
   messages at the Access Point, and subsequent verification of incoming
   messages is done at the Incoming Point.

   All communications within the PEC network MUST use secure channels.
   Integrity and confidentiality of connections between PEC provider and
   user MUST be guaranteed through the use of secure protocols, such as
   those based on [<a href="#ref-TLS" title="&quot;The Transport Layer Security (TLS) Protocol Version 1.2&quot;">TLS</a>] and those that create a secure transport channel
   on which non-secure protocols can transmit (e.g., IPsec).

   The interaction between providers MUST take place using SMTP on
   [<a href="#ref-TLS" title="&quot;The Transport Layer Security (TLS) Protocol Version 1.2&quot;">TLS</a>], as per [<a href="#ref-SMTP-TLS" title="&quot;SMTP Service Extension for Secure SMTP over Transport Layer Security&quot;">SMTP-TLS</a>].  The Incoming Point MUST provide and
   announce its support for the STARTTLS extension, as well as accept
   both unencrypted connections (for ordinary mail) and protected ones.
   To guarantee complete traceability in the flow of PEC messages, these
   MUST NOT transit on systems external to the PEC network.  When
   exchanging messages between different providers, all transactions
   MUST take place between machines that belong to the PEC network or
   are directly managed by the provider.  An "MX" type record MAY be
   associated to each PEC domain defined within the system for name
   resolution, in which case secondary reception systems specified in
   that record MUST be under direct control of the provider.  All in
   conformance with [<a href="#ref-SMTP" title="&quot;Simple Mail Transfer Protocol&quot;">SMTP</a>].

<span class="h3"><a class="selflink" id="section-5.4" href="#section-5.4">5.4</a>.  Virus</span>

   Another important security aspect that concerns the PEC system, is
   related to the technical and functional architecture that MUST block
   the presence of viruses from endangering the security of all handled
   messages.  It is therefore REQUIRED to have installations and
   continuous updates of anti-virus systems that hinder infections as
   much as possible without intervening on the content of the certified
   mail, in compliance with what has been discussed thus far.

<span class="h3"><a class="selflink" id="section-5.5" href="#section-5.5">5.5</a>.  S/MIME Certificate</span>

   In this document the S/MIME certificate profile is defined for use in
   the certification of PEC messages done by the providers.  The
   proposed profile of the S/MIME certificate is based on the IETF
   standards [<a href="#ref-SMIMECERT" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Certificate Handling&quot;">SMIMECERT</a>] and [<a href="#ref-CRL" title="&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile&quot;">CRL</a>], which in turn are based on the
   standard ISO/IEC 9594-8:2001.







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<span class="h4"><a class="selflink" id="section-5.5.1" href="#section-5.5.1">5.5.1</a>.  Provider-Related Information (Subject)</span>

   The information related to the PEC provider holder of the certificate
   MUST be inserted in the Subject field (Subject DN).  More precisely,
   the Subject DN MUST contain the PEC provider's name as it is in the
   "providerName" attribute published in the PEC providers directory
   (<a href="#section-4.5">section 4.5</a>), but the Subject DN does not have to match the Provider
   entry DN in the LDIF.  The providerName MUST be present in the
   CommonName or OrganizationName attributes of the "Subject:" field in
   the certificate.

   Certificates MUST contain an Internet mail address, which MUST have a
   value in the subjectAltName extension, and SHOULD NOT be present in
   the Subject Distinguished Name.

   Valid subjectDN are:

        C=IT, O=AcmePEC S.p.A, CN=Posta Certificata

        C=IT, O=ServiziPEC S.p.A, CN=Posta Certificata

   Valorization of other attributes in the Subject DN, if present, MUST
   be done in compliance with [<a href="#ref-CRL" title="&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile&quot;">CRL</a>].

<span class="h4"><a class="selflink" id="section-5.5.2" href="#section-5.5.2">5.5.2</a>.  Certificate Extensions</span>

   Extensions that MUST be present in the S/MIME certificate are:

   o  Key Usage

   o  Authority Key Identifier

   o  Subject Key Identifier

   o  Subject Alternative Name

   The Basic Constraints extension (Object ID:2.5.29.19) MUST NOT be
   present.

   The valorization of the above listed extensions for the described
   profile follows.

   The Key Usage extension (Object ID: 2.5.29.15) MUST have the
   digitalSignature bit (bit 0) activated and MUST be marked as
   critical.  The extension MAY contain other active bits corresponding
   to different Key Usage, as long as that doesn't contrast with the
   indications in [<a href="#ref-CRL" title="&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile&quot;">CRL</a>].




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   The Authority Key Identifier (Object ID: 2.5.29.35) MUST contain at
   least the keyIdentifier field and MUST NOT be marked as critical.

   The Subject Key Identifier extension (Object ID: 2.5.29.14) MUST
   contain at least the keyIdentifier field and MUST NOT be marked as
   critical.

   The Subject Alternative Name (Object ID: 2.5.29.17) MUST contain at
   least the rfc822Name field and MUST NOT be marked as critical.

   Adding other extensions that have not been described in this document
   is to be considered OPTIONAL, as long as it remains compliant with
   [<a href="#ref-CRL" title="&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile&quot;">CRL</a>]; such added extensions MUST NOT be marked as critical.

<span class="h4"><a class="selflink" id="section-5.5.3" href="#section-5.5.3">5.5.3</a>.  Example</span>

   Following is an example of an S/MIME certificate compliant with the
   minimal requisites described in this profile.  Values used are of
   fictitious providers generated for example purposes only.

<span class="h5"><a class="selflink" id="section-5.5.3.1" href="#section-5.5.3.1">5.5.3.1</a>.  General-Use Certificate in Annotated Version</span>

   An asterisk near the label of an extension means that such an
   extension has been marked as critical.

       VERSION: 3
       SERIAL: 11226 (0x2bda)
       INNER SIGNATURE:
         ALG. ID: id-sha1-with-rsa-encryption
         PARAMETER: 0
       ISSUER:
         Country Name: IT
         Organization Name: Certifier 1
         Organizational Unit Name: Certification Service Provider
         Common Name: Certifier S.p.A.
       VALIDITY:
         Not Before: Oct 5, 04 09:04:23 GMT
         Not After: Oct 5, 05 09:04:23 GMT
       SUBJECT:
         Country Name: IT
         Organization Name: AcmePEC S.p.A.
         Common Name: Certified Mail
       PUBLIC KEY: (key size is 1024 bits)
       ALGORITHM:
         ALG. ID: id-rsa-encryption
         PARAMETER: 0
       MODULUS: 0x00afbeb4 5563198a aa9bac3f 1b29b5be
                7f691945 89d01569 ca0d555b 5c33d7e9



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                ...
                d15ff128 6792def5 b3f884e6 54b326db
                cf
       EXPONENT: 0x010001
       EXTENSIONS:
         Subject Alt Name:
         RFC Name: posta-certificata@acmepec.it
         Key Usage*: Digital Signature
         Authority Key Identifier: 0x12345678 aaaaaaaa bbbbbbbb
                                   cccccccc dddddddd
         Subject Key Identifier: 0x3afae080 6453527a 3e5709d8 49a941a8
                                 a3a70ae1
       SIGNATURE:
         ALG. ID: id-sha1-with-rsa-encryption
         PARAMETER: 0
         VALUE: 0x874b4d25 70a46180 c9770a85 fe7923ce
                b22d2955 2f3af207 142b2aba 643aaa61
                ...
                d8fd10b4 c9e00ebc c089f7a3 549a1907
                ff885220 ce796328 b0f8ecac 86ffb1cc

<span class="h5"><a class="selflink" id="section-5.5.3.2" href="#section-5.5.3.2">5.5.3.2</a>.  General-Use Certificate in Dump ASN.1</span>

   0 30  794: SEQUENCE {
   4 30  514:  SEQUENCE {
   8 A0   3:   [0] {
   10 02  1:    INTEGER 2
       :      }
   13 02  2:   INTEGER 11226
   17 30   13:  SEQUENCE {
   19 06  9:    OBJECT IDENTIFIER
         :      sha1withRSAEncryption (1 2 840 113549 1 1 5)
   30 05  0:    NULL
         :    }
   32 30  101:  SEQUENCE {
   34 31   11:   SET {
   36 30   9:     SEQUENCE {
   38 06   3:      OBJECT IDENTIFIER countryName (2 5 4 6)
   43 13   2:      PrintableString 'IT'
         :      }
         :    }
   47 31   28:   SET {
   49 30   26:    SEQUENCE {
   51 06   3:      OBJECT IDENTIFIER organizationName (2 5 4 10)
   56 13   19:     PrintableString 'Certificatore 1'
         :      }
         :    }
   77 31   22:   SET {



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   79 30   20:    SEQUENCE {
   81 06   3:   OBJECT IDENTIFIER organizationalUnitName (2 5 4 11)
   86 13   13:    PrintableString 'Certification Service Provider'
         :      }
         :    }
   101 31  32:   SET {
   103 30  30:    SEQUENCE {
   105 06  3:      OBJECT IDENTIFIER commonName (2 5 4 3)
   110 13  23:     PrintableString 'Certificatore S.p.A.'
         :      }
         :    }
         :  }
   135 30  30:  SEQUENCE {
   137 17  13:   UTCTime '041005090423Z'
   152 17  13:   UTCTime '051005090423Z'
         :     }
   167 30  66:  SEQUENCE {
   169 31  11:   SET {
   171 30  9:     SEQUENCE {
   173 06  3:      OBJECT IDENTIFIER countryName (2 5 4 6)
   178 13  2:      PrintableString 'IT'
         :      }
         :    }
   182 31  23:  SET {
   184 30  21:   SEQUENCE {
   186 06  3:     OBJECT IDENTIFIER organizationName (2 5 4 10)
   191 13  14:    PrintableString 'AcmePEC S.p.A.'
         :      }
         :    }
   207 31  26:  SET {
   209 30  24:   SEQUENCE {
   211 06  3:     OBJECT IDENTIFIER commonName (2 5 4 3)
   216 13  17:    PrintableString 'Posta Certificata'
         :      }
         :    }
         :  }
   235 30  159: SEQUENCE {
   238 30  13:   SEQUENCE {
   240 06  9:     OBJECT IDENTIFIER rsaEncryption (1 2 840 113549
                  1 1 1)
   251 05  0:     NULL
         :      }
   253 03  141:  BIT STRING 0 unused bits
         :     30 81 89 02 81 81 00 AF BE B4 55 63 19 8A AA 9B
         :     AC 3F 1B 29 B5 BE 7F 69 19 45 89 D0 15 69 CA 0D
         :     55 5B 5C 33 D7 E9 C8 6E FC 14 46 C3 C3 09 47 DD
         :     CD 10 74 1D 76 4E 71 14 E7 69 42 BE 1C 47 61 85
         :     4D 74 76 DD 0B B5 78 4F 1E 84 DD B4 86 7F 96 DF



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         :     5E 7B AF 0E CE EA 12 57 0B DF 9B 63 67 4D F9 37
         :     B7 48 35 27 C2 89 F3 C3 54 66 F7 DA 6C BE 4F 5D
         :     85 55 07 A4 97 8C D1 5F F1 28 67 92 DE F5 B3 F8
         :         [ Another 12 bytes skipped ]
         :    }
   397 A3  123: [3] {
   399 30  121:  SEQUENCE {
   401 30  39:    SEQUENCE {
   403 06  3:      OBJECT IDENTIFIER subjectAltName (2 5 29 17)
   408 04  32:     OCTET STRING
         :      30 1E 81 1C 70 6F 73 74 61 2D 63 65 72 74 69 66
         :      69 63 61 74 61 40 61 63 6D 65 70 65 63 2E 69 74
         :     }
   442 30  14:   SEQUENCE {
   444 06  3:     OBJECT IDENTIFIER keyUsage (2 5 29 15)
   449 01  1:     BOOLEAN TRUE
   452 04  4:     OCTET STRING
         :      03 02 07 80
         :      }
   458 30  31:   SEQUENCE {
   460 06  3:  OBJECT IDENTIFIER authorityKeyIdentifier (2 5 29 35)
   465 04  24:    OCTET STRING
         :     30 16 11 11 11 11 AA AA AA AA AA BB BB BB BB CC CC
         :     CC CC DD DD DD DD
         :      }
   491 30  29:   SEQUENCE {
   493 06  3:    OBJECT IDENTIFIER subjectKeyIdentifier (2 5 29 14)
   498 04  22:    OCTET STRING
         :      04 14 3A FA E0 80 64 53 52 7A 3E 57 09 D8 49 A9
         :      41 A8 A3 A7 0A E1
         :      }
         :     }
         :    }
         :   }
   522 30  13: SEQUENCE {
   524 06  9:   OBJECT IDENTIFIER
         :      sha1withRSAEncryption (1 2 840 113549 1 1 5)
   535 05  0:   NULL
         :    }
   537 03  257: BIT STRING 0 unused bits
         :     87 4B 4D 25 70 A4 61 80 C9 77 0A 85 FE 79 23 CE
         :     B2 2D 29 55 2F 3A F2 07 14 2B 2A BA 64 3A AA 61
         :     1F F0 E7 3F C4 E6 13 E2 09 3D F0 E1 83 A0 C0 F2
         :     C6 71 7F 3A 1C 80 7F 15 B3 D6 1E 22 79 B8 AC 91
         :     51 83 F2 3A 84 86 B6 07 2B 22 E8 01 52 2D A4 50
         :     9F C6 42 D4 7C 38 B1 DD 88 CD FC E8 C3 12 C3 62
         :     64 0F 16 BF 70 15 BC 01 16 78 30 2A DA FA F3 70
         :     E2 D3 0F 00 B0 FD 92 11 6C 55 45 48 F5 64 ED 98



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         :         [ Another 128 bytes skipped ]
         : }

<span class="h3"><a class="selflink" id="section-5.6" href="#section-5.6">5.6</a>.  PEC Providers Directory</span>

   The contents of the PEC providers directory MUST be queried via
   [<a href="#ref-HTTP" title="&quot;Hypertext Transfer Protocol -- HTTP/1.1&quot;">HTTP</a>] on a Secure Socket Layer (SSL), as described in [<a href="#ref-TLS" title="&quot;The Transport Layer Security (TLS) Protocol Version 1.2&quot;">TLS</a>],
   exclusively by licensed providers that have the necessary user
   certificates; this access modality guarantees authenticity,
   integrity, and confidentiality of data.  Each provider downloads the
   LDIF file through an [<a href="#ref-HTTPS" title="&quot;HTTP Over TLS&quot;">HTTPS</a>] session, which is authenticated by
   checking the X.509 certificate issued by a certification authority.

<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>.  PEC System Client Technical and Functional Prerequisites</span>

   This section lists the prerequisites that must be respected by a
   client in order to guarantee the minimal operative functionalities to
   the user of a general PEC system:

   o  handling of Access and Delivery Points through secure channels;

   o  handling of user authentication in message dispatch and reception
      which make use of standard protocols, such as [<a href="#ref-IMAP" title="&quot;INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1&quot;">IMAP</a>], [<a href="#ref-POP3" title="&quot;Post Office Protocol - Version 3&quot;">POP3</a>], and
      [<a href="#ref-HTTP" title="&quot;Hypertext Transfer Protocol -- HTTP/1.1&quot;">HTTP</a>];

   o  support for MIME format according to [<a href="#ref-MIME1" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies&quot;">MIME1</a>] and [<a href="#ref-MIME5" title="&quot;Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples&quot;">MIME5</a>];

   o  support for "ISO-8859-1 (Latin-1)" character set;

   o  support for S/MIME v3 standard, as in [<a href="#ref-SMIMEV3" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification&quot;">SMIMEV3</a>], for verification
      of signatures applied to PEC envelopes and notifications.

<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>.  Security Considerations</span>

   All security considerations from [<a href="#ref-CMS" title="&quot;Cryptographic Message Syntax (CMS)&quot;">CMS</a>] and [<a href="#ref-SMIMEV3" title="&quot;Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification&quot;">SMIMEV3</a>] apply to
   applications that use procedures described in this document.

   The centralized LDAP server is a critical point for the security of
   the whole PEC system.  An attack could compromise the whole PEC
   system.  PEC providers that periodically download the LDIF file
   SHOULD use the best security technology to protect it from local
   attacks.  A PEC provider could be compromised if an attacker changed
   a certificate or modified the list of domains associated to it in the
   LDIF file that was copied to the PEC provider system.







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   When verifying the validity of the signature of a message, the
   recipient system SHOULD verify that the certificate included in the
   [<a href="#ref-CMS" title="&quot;Cryptographic Message Syntax (CMS)&quot;">CMS</a>] message is present in the LDIF file (<a href="#section-4.5">section 4.5</a>) and that the
   domain extracted by the [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>] "From:" header is listed in the
   managedDomains attribute associated to said certificate.

<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>.  IANA Considerations</span>

<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>.  Registration of PEC Message Header Fields</span>

   This document defines new header fields used in the messages that
   transit in the PEC network.  As specified and required by
   [<a href="#ref-HEADERS-IANA" title="&quot;Registration Procedures for Message Header Fields&quot;">HEADERS-IANA</a>], this document registers new header fields as
   Provisional Message Header Fields as follows.

<span class="h4"><a class="selflink" id="section-8.1.1" href="#section-8.1.1">8.1.1</a>.  Header Field: X-Riferimento-Message-ID:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional

   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Specification document: this document, <a href="#section-2.2.1">section 2.2.1</a>, <a href="#appendix-A">Appendix A</a>.

<span class="h4"><a class="selflink" id="section-8.1.2" href="#section-8.1.2">8.1.2</a>.  Header Field: X-Ricevuta:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional

   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it





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   Specification document: this document, sections <a href="#section-2.1.1.1.1">2.1.1.1.1</a>, <a href="#section-3.1.2">3.1.2</a>,
                           3.1.3, 3.1.4, 3.1.6, 3.2.1, 3.2.3, 3.2.4,
                           3.3.2, 3.3.3, <a href="#appendix-A">Appendix A</a>.

<span class="h4"><a class="selflink" id="section-8.1.3" href="#section-8.1.3">8.1.3</a>.  Header Field: X-VerificaSicurezza:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional

   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Specification document: this document, sections <a href="#section-2.1.1.1.3">2.1.1.1.3</a>, <a href="#section-3.1.3">3.1.3</a>,
                           3.2.4, <a href="#appendix-A">Appendix A</a>.

<span class="h4"><a class="selflink" id="section-8.1.4" href="#section-8.1.4">8.1.4</a>.  Header Field: X-Trasporto:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional

   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Specification document: this document, sections <a href="#section-3.1.5">3.1.5</a>, <a href="#section-3.2.2">3.2.2</a>,
                           <a href="#appendix-A">Appendix A</a>.

<span class="h4"><a class="selflink" id="section-8.1.5" href="#section-8.1.5">8.1.5</a>.  Header Field: X-TipoRicevuta:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional






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   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Specification document: this document, sections <a href="#section-3.1.5">3.1.5</a>, <a href="#section-3.3.2">3.3.2</a>,
                           3.3.2.1, 3.3.2.2, 3.3.2.3, <a href="#appendix-A">Appendix A</a>.

<span class="h4"><a class="selflink" id="section-8.1.6" href="#section-8.1.6">8.1.6</a>.  Header Field: X-Mittente:</span>

   Applicable protocol: mail [<a href="#ref-EMAIL" title="&quot;Internet Message Format&quot;">EMAIL</a>]

   Status: provisional

   Author/Change controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Specification document: this document, sections <a href="#section-3.2.3">3.2.3</a>, <a href="#appendix-A">Appendix A</a>.

<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>.  Registration of LDAP Object Identifier Descriptors</span>

   This document defines new LDAP attributes and object classes for
   object identifier descriptors.  As specified and required by
   [<a href="#ref-LDAP-IANA" title="&quot;Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)&quot;">LDAP-IANA</a>], this document registers new descriptors as follows per
   the Expert Review.

<span class="h4"><a class="selflink" id="section-8.2.1" href="#section-8.2.1">8.2.1</a>.  Registration of Object Classes and Attribute Types</span>

   Subject: Request for LDAP Descriptor Registration

   Descriptor (short name): See comments

   Object Identifier: See comments

   Person &amp; email address to contact for further information:
      See "Author/Change Controller"

   Usage: See comments



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   Specification: (I-D)

   Author/Change Controller:

      Claudio Petrucci
      DigitPA
      Viale Carlo Marx 31/49
      00137 Roma
      Italy
      EMail: PETRUCCI@digitpa.gov.it

   Comments:

      The following object identifiers and associated object classes/
      attribute types are requested to be registered.

   OID                         Descriptor              Usage
   ------------------------    ---------------------   ------
   1.3.6.1.4.1.16572.2.1.1     LDIFLocationURLObject      O
   1.3.6.1.4.1.16572.2.1.2     provider                   O
   1.3.6.1.4.1.16572.2.2.1     providerCertificateHash    A
   1.3.6.1.4.1.16572.2.2.2     providerCertificate        A
   1.3.6.1.4.1.16572.2.2.3     providerName               A
   1.3.6.1.4.1.16572.2.2.4     mailReceipt                A
   1.3.6.1.4.1.16572.2.2.5     managedDomains             A
   1.3.6.1.4.1.16572.2.2.6     LDIFLocationURL            A
   1.3.6.1.4.1.16572.2.2.7     providerUnit               A

   Legend
   -------------------
   O =&gt; Object Class
   A =&gt; Attribute Type

<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>.  References</span>

<span class="h3"><a class="selflink" id="section-9.1" href="#section-9.1">9.1</a>.  Normative References</span>

   [<a id="ref-ABNF">ABNF</a>]          Crocker, D., Ed., and P. Overell, "Augmented BNF for
                   Syntax Specifications: ABNF", STD 68, <a href="./rfc5234">RFC 5234</a>,
                   January 2008.

   [<a id="ref-CMS">CMS</a>]           Housley, R., "Cryptographic Message Syntax (CMS)",
                   STD 70, <a href="./rfc5652">RFC 5652</a>, September 2009.

   [<a id="ref-CRL">CRL</a>]           Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
                   Housley, R., and W. Polk, "Internet X.509 Public Key
                   Infrastructure Certificate and Certificate Revocation
                   List (CRL) Profile", <a href="./rfc5280">RFC 5280</a>, May 2008.



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   [<a id="ref-EMAIL">EMAIL</a>]         Resnick, P., Ed., "Internet Message Format", <a href="./rfc5322">RFC</a>
                   <a href="./rfc5322">5322</a>, October 2008.

   [<a id="ref-HEADERS-IANA">HEADERS-IANA</a>]  Klyne, G., Nottingham, M., and J. Mogul,
                   "Registration Procedures for Message Header Fields",
                   <a href="https://www.rfc-editor.org/bcp/bcp90">BCP 90</a>, <a href="./rfc3864">RFC 3864</a>, September 2004.

   [<a id="ref-HTTP">HTTP</a>]          Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
                   Masinter, L., Leach, P., and T. Berners-Lee,
                   "Hypertext Transfer Protocol -- HTTP/1.1", <a href="./rfc2616">RFC 2616</a>,
                   June 1999.

   [<a id="ref-HTTPS">HTTPS</a>]         Rescorla, E., "HTTP Over TLS", <a href="./rfc2818">RFC 2818</a>, May 2000.

   [<a id="ref-IMAP">IMAP</a>]          Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -
                   VERSION 4rev1", <a href="./rfc3501">RFC 3501</a>, March 2003.

   [<a id="ref-LDAP">LDAP</a>]          Zeilenga, K., Ed., "Lightweight Directory Access
                   Protocol (LDAP): Technical Specification Road Map",
                   <a href="./rfc4510">RFC 4510</a>, June 2006.

   [<a id="ref-LDAP-IANA">LDAP-IANA</a>]     Zeilenga, K., "Internet Assigned Numbers Authority
                   (IANA) Considerations for the Lightweight Directory
                   Access Protocol (LDAP)", <a href="https://www.rfc-editor.org/bcp/bcp64">BCP 64</a>, <a href="./rfc4520">RFC 4520</a>, June 2006.

   [<a id="ref-LDAP-SYNTAXES">LDAP-SYNTAXES</a>] Legg, S., Ed., "Lightweight Directory Access Protocol
                   (LDAP): Syntaxes and Matching Rules", <a href="./rfc4517">RFC 4517</a>, June
                   2006.

   [<a id="ref-LDIF">LDIF</a>]          Good, G., "The LDAP Data Interchange Format (LDIF) -
                   Technical Specification", <a href="./rfc2849">RFC 2849</a>, June 2000.

   [<a id="ref-MIME1">MIME1</a>]         Freed, N. and N. Borenstein, "Multipurpose Internet
                   Mail Extensions (MIME) Part One: Format of Internet
                   Message Bodies", <a href="./rfc2045">RFC 2045</a>, November 1996.

   [<a id="ref-MIME5">MIME5</a>]         Freed, N. and N. Borenstein, "Multipurpose Internet
                   Mail Extensions (MIME) Part Five: Conformance
                   Criteria and Examples", <a href="./rfc2049">RFC 2049</a>, November 1996.

   [<a id="ref-SUBMISSION">SUBMISSION</a>]    Gellens, R. and J. Klensin, "Message Submission for
                   Mail", <a href="./rfc4409">RFC 4409</a>, April 2006.

   [<a id="ref-POP3">POP3</a>]          Myers, J. and M. Rose, "Post Office Protocol -
                   Version 3", STD 53, <a href="./rfc1939">RFC 1939</a>, May 1996.






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   [<a id="ref-REQ">REQ</a>]           Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.

   [<a id="ref-SHA1">SHA1</a>]          Eastlake 3rd, D. and P. Jones, "US Secure Hash
                   Algorithm 1 (SHA1)", <a href="./rfc3174">RFC 3174</a>, September 2001.

   [<a id="ref-MIME-SECURE">MIME-SECURE</a>]   Galvin, J., Murphy, S., Crocker, S., and N. Freed,
                   "Security Multiparts for MIME: Multipart/Signed and
                   Multipart/Encrypted", <a href="./rfc1847">RFC 1847</a>, October 1995.

   [<a id="ref-SMIMEV3">SMIMEV3</a>]       Ramsdell, B. and S. Turner, "Secure/Multipurpose
                   Internet Mail Extensions (S/MIME) Version 3.2 Message
                   Specification", <a href="./rfc5751">RFC 5751</a>, January 2010.

   [<a id="ref-SMIMECERT">SMIMECERT</a>]     Ramsdell, B. and S. Turner, "Secure/Multipurpose
                   Internet Mail Extensions (S/MIME) Version 3.2
                   Certificate Handling", <a href="./rfc5750">RFC 5750</a>, January 2010.

   [<a id="ref-SMTP">SMTP</a>]          Klensin, J., "Simple Mail Transfer Protocol", <a href="./rfc5321">RFC</a>
                   <a href="./rfc5321">5321</a>, October 2008.

   [<a id="ref-SMTP-DSN">SMTP-DSN</a>]      Moore, K., "Simple Mail Transfer Protocol (SMTP)
                   Service Extension for Delivery Status Notifications
                   (DSNs)", <a href="./rfc3461">RFC 3461</a>, January 2003.

   [<a id="ref-SMTP-TLS">SMTP-TLS</a>]      Hoffman, P., "SMTP Service Extension for Secure SMTP
                   over Transport Layer Security", <a href="./rfc3207">RFC 3207</a>, February
                   2002.

   [<a id="ref-TIMESTAMP">TIMESTAMP</a>]     Klyne, G. and C. Newman, "Date and Time on the
                   Internet: Timestamps", <a href="./rfc3339">RFC 3339</a>, July 2002.

   [<a id="ref-TLS">TLS</a>]           Dierks, T. and E. Rescorla, "The Transport Layer
                   Security (TLS) Protocol Version 1.2", <a href="./rfc5246">RFC 5246</a>,
                   August 2008.

   [<a id="ref-XML">XML</a>]           W3C, "Extensible Markup Language (XML) 1.0 (Fifth
                   Edition)", W3C Recommendation, November 2008,
                   &lt;<a href="http://www.w3.org/TR/2006/REC-xml-20060816/">http://www.w3.org/TR/2006/REC-xml-20060816/</a>&gt;.

<span class="h3"><a class="selflink" id="section-9.2" href="#section-9.2">9.2</a>. Informative References</span>

   [<a id="ref-RFC1034">RFC1034</a>]       Mockapetris, P., "Domain names - concepts and
                   facilities", STD 13, <a href="./rfc1034">RFC 1034</a>, November 1987.







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   [<a id="ref-RFC4522">RFC4522</a>]       Legg, S., "Lightweight Directory Access Protocol
                   (LDAP): The Binary Encoding Option", <a href="./rfc4522">RFC 4522</a>, June
                   2006.

   [<a id="ref-RFC4523">RFC4523</a>]      Zeilenga, K., "Lightweight Directory Access Protocol
                   (LDAP) Schema Definitions for X.509 Certificates",
                   <a href="./rfc4523">RFC 4523</a>, June 2006.

<span class="h2"><a class="selflink" id="section-10" href="#section-10">10</a>.  Acknowledgments</span>

   The Italian document on which this document is based, is a product of
   the collaboration of many with the supervision of the National Center
   for Informatics in the Public Administration of Italy (DigitPA).






































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<span class="h2"><a class="selflink" id="appendix-A" href="#appendix-A">Appendix A</a>.  Italian Fields and Values in English</span>

   NOTE: The right column represents a translation of the Italian fields
         for readability's sake only.  Header fields that MUST be used
         are the ones in the left column.

    X-Riferimento-Message-ID        Reference Message Identifier
    X-Ricevuta                      Notification
      non-accettazione                non acceptance
      accettazione                    server-user acceptance
      preavviso-errore-consegna       delivery error advance notice
      presa-in-carico                 server-server acceptance
      rilevazione-virus               virus detection
      errore-consegna                 delivery error
      avvenuta-consegna               message delivered
    X-Mittente                      Sender
    X-VerificaSicurezza             Security Verification
      errore                          error
    X-Trasporto                     Transport
      posta-certificata               certified mail
      errore                          error
    X-TipoRicevuta                  Notification Type
      completa                        complete
      breve                           brief
      sintetica                       concise

    certificatore                   certificator

    Subject values:

      Accettazione                   SERVER-USER ACCEPTANCE
      Posta certificata              CERTIFIED MAIL
      Presa in carico                SERVER-SERVER ACCEPTANCE
      Consegna                       DELIVERY
      Anomalia messaggio             MESSAGE ANOMALY
      Problema di sicurezza          SECURITY PROBLEM
      Avviso di non accettazione     NON ACCEPTANCE PEC NOTIFICATION
      Avviso di non accettazione     VIRUS DETECTION INDUCED NON
      per virus                      ACCEPTANCE PEC NOTIFICATION
      Avviso di mancata consegna     NON DELIVERY PEC NOTIFICATION
      Avviso di mancata consegna     NON DELIVERY DUE TO VIRUS PEC
      per virus                      NOTIFICATION
      Avviso di mancata consegna     NON DELIVERY DUE TO TIMEOUT PEC
      per sup. tempo massimo         NOTIFICATION







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   Italian terms in the DTD relative to the certification XML file:

      accettazione                   server-user acceptance
      altro                          other
      avvenuta-consegna              delivered
      certificato                    certificate
      consegna                       delivery
      data                           date
      dati                           data
      destinatari                    recipients
      esterno                        external
      errore                         error
      errore-consegna                delivery error
      errore-esteso                  extensive error
      gestore-emittente              transmitting provider
      giorno                         day
      identificativo                 identifier
      intestazione                   header
      mittente                       sender
      no-dest(inatario)              no recipient
      no-dominio                     no domain
      non-accettazione               non acceptance
      nessuno                        none
      oggetto                        subject
      ora                            hour
      posta-certificata              certified mail
      preavviso-errore-consegna      delivery error advance notice
      presa-in-carico                server-server acceptance
      ricevuta                       notification
      ricezione                      receipt (the act of receiving)
      rilevazione-virus              virus detection
      risposte                       replies
      tipo                           type


















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Authors' Addresses

   Claudio Petrucci
   DigitPA
   Viale Marx 31/49
   00137 Roma
   Italy

   EMail: petrucci@digitpa.gov.it

   Francesco Gennai
   ISTI-CNR
   Via Moruzzi, 1
   56126 Pisa
   Italy

   EMail: francesco.gennai@isti.cnr.it


   Alba Shahin
   ISTI-CNR
   Via Moruzzi, 1
   56126 Pisa
   Italy

   EMail: alba.shahin@isti.cnr.it


   Alessandro Vinciarelli
   Via delle Vigne di Morena 113
   00118 Roma
   Italy

   EMail: alessandro.vinciarelli@gmail.com

















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