I’ve also maintained a bit of an amateur interest in cryptography. While I understand a bit about modern ciphers such as DES, IDEAL and RC4, I find it more fun to play with older cryptosystems. When Simon Singh published his book The Code Book, I decided to work through the Cipher Challenge at the back. While I didn’t win the $10,000 prize, I did manage to crack 7 out of 10 ciphers, including the Playfair, ADGVX cipher and the German Enigma machine (which took the most work and was the most fun). I still am fascinated by old crypto machines. My friend Jeff actually owns an M209 field cipher machine, which I dug up a simulator for out of the old Version 6 Unix distribution.

Anyway, while scanning sci.crypt, I ran accross this interesting link to a paper simulation of the 3 rotor German Enigma machine. If
I had this while I was debugging my simulator, it probably would have shaved several weeks off my efforts. Much thanks to Michael Koss, who is a collector
of crypto machines, and to John Malley for putting some of the photos of his collection up on the net. I’m completely jealous.