Openwall
You're allowed to do whatever you like with this software (including re-distribution in source and/or binary form, with or without modification), provided that credit is given where it is due and any modified versions are marked as such. There's absolutely no warranty. [Note that you don't have to re-distribute this software under these same relaxed terms. In particular, you're free to place modified versions under (L)GPL, thus disallowing further re-distribution in binary-only form.]