That's a Federal Information Processing Standard. This one is for DES. If you Google it, and fail to find the real McCoy something's wrong. I got 781000+ hits on FIPS 46, the first of which was the real McCOY.

http://csrc.nist.gov/publicati...ps46-3.pdf

Until you know what you want, you'd best pound on your client/employer to give you firm requirements, particularly an acceptance testing specification. In some respects, cryptography is like black magic. You can waste years on some strategies without getting one implementation that's working right.

The '51 series has an ecryption table that you can use for various encryption schemes. If you can find the old writeups, that might help.

If you can't get a straight answer or can't decide, then do spend a little time with DES. That one is "tried and true," and even NSA has trouble cracking it.

With DES, the real problem becomes one of secure key management.

The first thing you'll want to know, though, is the throughput requirement. The process is slow and tedious, and it consumes a fair amount of time. That's a good thing, because it otherwise doesn't take long to crack it either.

RE