Rainbow tables

I'm fascinated by Cryptography. I just never get around to brush up on my mathematics. I have seen the mention of Rainbowtables before. Actually it's quite easily demystified. Most passwords are or should be hashed. A method of one-way encryption. One of the only methods to crack these is through bruteforce. Which is quite resource intensive. How do we get around this? Keep a table of as much possible hashes and perform a lookup. You can't decrypt it but it's kind of a loophole to 'find' the password faster then a simple bruteforce. It is easily defeated using salt. Another disadvantage that a table can never hold 'all' combinations. The bigger the rainbowtable, the bigger chance it contains 'the' password.

The full explanation is here. Also a 'fun' read about cryptography : Cryptonomicon.

Statistics

Average running time for of the demo, using table set SSTIC04-2.7k (1.1GB)

alphanumeric passwords:	1.67 seconds
paswords with one non-alphanumeric half:	26.14 seconds
passwords with two non-alphanumeric halves (not cracked):	42.14 seconds

Cracking times may vary when the server is also doing other calculations