NAME

       srm - secure remove (secure_deletion toolkit)

SYNOPSIS

       srm [-d] [-f] [-l] [-l] [-r] [-v] [-z] files

DESCRIPTION

       srm is designed to delete data on mediums in a secure manner which can not be recovered by
       thieves, 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.

       The secure data deletion process of srm goes like this:

       *      1 pass with 0xff

       *      5 random passes. /dev/urandom is used for a secure RNG if available.

       *      27 passes with special values defined by Peter Gutmann.

       *      5 random passes. /dev/urandom is used for a secure RNG if available.

       *      Rename the file to a random value

       *      Truncate the file

       As an additional measure of security, the file is opened in O_SYNC  mode  and  after  each
       pass  an  fsync()  call  is done.  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.

COMMANDLINE OPTIONS

       -d     ignore  the  two special dot files . and .. on the commandline. (so you can execute
              it like "srm -d .* *")

       -f     fast (and insecure mode): no /dev/urandom, no synchronize mode.

       -l     lessens the security. Only two passes are written: one mode with 0xff and  a  final
              mode random values.

       -l     -l  for  a  second  time  lessons  the  security even more: only one random pass is
              written.

       -r     recursive mode, deletes all subdirectories.

       -v     verbose mode

       -z     wipes the last write with zeros instead of random data

LIMITATIONS

       NFS    Beware of NFS. You can't ensure you really completely  wiped  your  data  from  the
              remote disks.

       Raid   Raid Systems use stripped disks and have got large caches. It's hard to wipe them.

       swap, /tmp, etc.
              Some  of your data might have a temporary (deleted) copy somewhere on the disk. You
              should use sfill which comes with the secure_deletion package  to  ensure  to  wipe
              also  the  free  diskspace.  However, If already a small file acquired a block with
              your precious data, no tool known to me can help you here. For a secure deletion of
              the swap space sswap is available.

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 :)

AUTHOR

       van Hauser / THC <vh@thc.org>

DISTRIBUTION

       The newest version of the secure_deletion package can be obtained from http://www.thc.org

       srm and the secure_deletion package is (C) 1997-2003 by van Hauser / THC (vh@thc.org)

       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.

       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.

SEE ALSO

       sfill (1), sswap (1), sdmem (1)

                                                                                           SRM(1)