Contrary to popular belief, Unix passwords cannot be decrypted. Unix

passwords are encrypted with a one way function. The login program

encrypts the text you enter at the "password:" prompt and compares

that encrypted string against the encrypted form of your password.

Password cracking software uses wordlists. Each word in the wordlist

is encrypted with each of the 2600 possible salt values and the

results are compared to the encrypted form of the target password.

The best cracking program for Unix passwords is currently Crack by

Alec Muffett. For PC-DOS, the best package to use is currently

CrackerJack.