Yeah ActivePerl, but I remember taking some time to install it... don't remember, maybe it was the oldschool comp I used to have

I had to write such a program in Perl [I wrote it in Perl because it was easiest] that would need to find the original string that got md5 hashed twice... a basic brute forcing tool, I know. It took only a few lines of code. And yes, it was done for legal purposes [the GEEK challenges ]