RainbowCrack is a general propose implementation of Philippe Oechslin's faster
time-memory trade-off technique.

In short, the RainbowCrack tool is a hash cracker. A traditional brute force
cracker tries all possible plaintexts one by one in cracking time. It is time
consuming to break complex passwords this way. The idea of time-memory trade-off
is to do all cracking time computation in advance and store the result in files
so called "rainbow table". It does take a long time to precompute the tables.
But once the one time precomputation is finished, a time-memory trade-off
cracker can be hundreds of times faster than a brute force cracker, with the
help of precomputed tables.

WWW: http://www.antsight.com/zsl/rainbowcrack/