SHA-1 Cracker

C implementation of a SHA-1 (https://en.wikipedia.org/wiki/SHA-1) cracker with various optimizations.
This was an assignment at university where we had to find the preimage of a given SHA-1 hash. In our scenario, the preimage was guaranteed to be six lower-case letters (for example, "aaaaaa" or "passwd"). In addition to general optimizations such as meet-in-the-middle, initial-step, early-exit (https://hashcat.net/events/p13/), those limitations allowed for further scenario-specific optimizations (mainly by identifying constants).