Hashes and Message Digests
Essentially one-way “digests” of messages. With msg M, function H:
- hard: find different M, M’ where H(M)=H(M’)
- hard: given H(M), find M
- easy: given M, produce H(M)
Common example is MD5
- hashes arbitrarily-long messages to 128-bit signature (RFC1321)
- used for file verification, IPSEC, etc