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)