NOTE: This will reply will not help you with any Perl coding.

First of all:
what type of algorithm does your UNIX password use?

DES?
You actually got a change of decrypting this in your lifetime ;)

3DES?
If you're even thinking of brute-forcing 3DES you probably should run and get yourself a couple of CRAY's or start building a bad-ass Beowulf.

AES?
Mail me when the universe implodes.

SERIOUS: In order to crack/decrypt you need to know the algorithm.

//PixelRat