unixcrypt-breaker is an automated tool for breaking the
encryption of the old unix crypt(1) utility. It can guess
substantial portions of the plaintext without previous knowledge of
It is well-known that unix crypt provides only weak security. Existing software for breaking it includes the Crypt Breaker's Workbench (http://axion.physics.ubc.ca/cbw.html). Unlike the Crypt Breaker's Workbench, unixcrypt-breaker is fully automatic and does not require user interaction. Rather than relying on the user to guess likely plaintexts, unixcrypt-breaker uses a statistical model for guessing plausible plaintexts.
To guess the plaintext correctly, unixcrypt-breaker must first be primed with a body of sample data (the "corpus") that is presumed to be similar to the unknown plaintext. For example, if the plaintext is assumed to be HTML data, then unixcrypt-breaker should be primed with a corpus of HTML data.
For a more detailed list of changes, see the ChangeLog.
February 1, 2008: First public release.
Unixcrypt-Breaker is built from sources using the standard
configure/make commands. Please see the file INSTALL
for detailed instructions. If you would like to ensure the accuracy of
the downloaded files, you can double-check their SHA1 sums.
unixcrypt-breaker -s /tmp/stats.txt -c plain1 plain2 plain3This will write some statistical information about the plaintext files to the file /tmp/stats.txt. Then, decrypt file.cpt with the following command:
unixcrypt-breaker -s /tmp/stats.txt file.cptThe output is written to file.cpt.guess.
|For detailed usage information, see the man page.|
|Copyright © 2006-2008 Peter Selinger.|
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; either version 2, or (at your option)
any later version.|
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.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
The GNU General Public License is contained in the file COPYING that is distributed with this software.