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.\" This definition swiped from the gcc(1) man page
.de Sp
.if n .sp
.if t .sp 0.4
..
.TH SRM 1
.SH NAME
srm \- secure remove (secure_deletion toolkit)
.SH SYNOPSIS
.B srm [-d] [-f] [-l] [-l] [-r] [-v] [-z] files
.SH DESCRIPTION
.I srm
is designed to delete data on mediums in a secure manner which can not be
recovered by thiefs, law enforcement or other threats.
The wipe algorythm is based on the paper "Secure Deletion of Data from
Magnetic and Solid-State Memory" presented at the 6th Usenix Security
Symposium by Peter Gutmann, one of the leading civilian cryptographers.
.PP
The
.I secure data deletion
process of srm goes like this:
.PP
.TP
.B *
1 pass with 0xff
.TP
.B *
5 random passes. /dev/urandom is used for a secure RNG if available.
.TP
.B *
27 passes with special values defined by Peter Gutmann.
.TP
.B *
5 random passes. /dev/urandom is used for a secure RNG if available.
.TP
.B *
Rename the file to a random value
.TP
.B *
Truncate the file
.PP
.PP
As an additional measure of security, the file is opened in O_SYNC mode
and after each pass an fsync() call is done.
.I srm
writes 32k blocks for the purpose of speed, filling buffers of disk caches
to force them to flush and overwriting old data which belonged to the file.
.PP
.SH COMMANDLINE OPTIONS
.PP
.TP
.B \-d
ignore the two special dot files . and .. on the commandline. (so you can
execute it like "srm -d .* *")
.TP
.B \-f
fast (and insecure mode): no /dev/urandom, no synchronize mode.
.TP
.B \-l
lessens the security. Only two passes are written: one mode with 0xff
and a final mode random values.
.TP
.B \-l
-l for a second time lessons the security even more: only one random pass
is written.
.TP
.B \-r
recursive mode, deletes all subdirectories.
.TP
.B \-v
verbose mode
.TP
.B \-z
wipes the last write with zeros instead of random data
.PP
.SH LIMITATIONS
.TP
.B NFS
Beware of NFS. You can't ensure you really completely wiped your data
from the remote disks.
.TP
.B Raid
Raid Systems use stripped disks and have got large caches. It's hard to wipe
them.
.TP
.B swap, /tmp, etc.
Some of your data might have a temporary (deleted) copy somewhere on the
disk. You should use
.I sfill
which comes with the
.I secure_deletion package
to ensure to wipe also the free diskspace. However, If already a small
file aquired a block with your precious data, no tool known to me can help
you here. For a secure deletion of the swap space
.I sswap
is available.
.PP
.SH BUGS
No bugs. There was never a bug in the secure_deletion package (in contrast
to my other tools, whew, good luck ;-)
Send me any that you find. Patches are nice too :)
.SH AUTHOR
.Sp
van Hauser / THC
.I <vh@thc.org>
.SH DISTRIBUTION
The newest version of the
.I secure_deletion package
can be obtained from
.I http://www.thc.org
.Sp
.I srm
and the
.I secure_deletion package
is (C) 1997-2003 by van Hauser / THC (vh@thc.org)
.Sp
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; Version 2.
.Sp
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
.SH SEE ALSO
.I sfill
(1),
.I sswap
(1),
.I smem
(1)
|
