Don't know what type of hash it is? Name That Hash will name that hash type! Identify MD5, SHA256 and 3000+ other hashes. Comes with a neat web app (which is optional). Can also be pulled in as a Python module for use in other projects.
The homepage of Paul Crowley.
The full text of The Handbook of Applied Cryptography, one of the best textbooks available in the field. The original authors have gotten permission from the publisher to put the text online as sets of PostScript and .pdf files for anyone to download and share.
From here you can purchase a DIY kit for a circuit that implements the German Enigma cypher from World War II. Fun for cypherpunks, electronics mavens, and geeks!
3697 links, including 185 private