As of 2011, a home computer with a dual-core processor will
find a 40 bit rc4 key within approximately one week. Since
rc4_40bit_key_search has been developed with support for
multi-core systems, the time to break a 40 bit rc4 key is
expected to come down in the future. Rc4 keys that are
shorter than 40 bits will also be found.

To build rc4_40bit_key_search type 'make' (or 'gmake' if you
have BSD-make as default). You will need GNU Make and a recent
version of GCC. OpenMP is also required, as rc4_40bit_key_search
has been developed with support for multi-core systems.

rc4_40bit_key_search requires to input parameters. These are the
original (unencrypted) string and its encrypted version. Both of
these strings must be specified in hexadecimal format. A
hexadecimal string will typically look like ABCD120570. Mind you
the input and the ouput string must be equal in length.

Code and documentation are copyright 2010 Daniela MANTOVANI.

Parts of rc4_40bit_key_search.c and rc4_40bit_key_search.h have
been derived/copied/inspired from pdfcrack. Pdfcrack is
copyright 2006-2008 Henning Norén.

The program is distributed under GPL version 2 (or later).