I felt the amount of good and accurate information about World War II era cryptography on everything was rather lacking, so I decided to copy the descriptions I wrote for my thinkquest site into everything. If you like what you read you really might want to check out my site at http://dev.thinkquest.org/C004911/ where you can use java emulators of just about all of the machines I describe.

The articles themselves are written from the point of view of either the US, UK, USSR, Japan or Germany at about 1942.

United States:
SIGABA
The Purple break.
USSR:
One Time Pad
Soviet Espionage Cipher
United Kingdom
Typex
The Enigma break.
Japan
JN-25
Purple
Germany
Enigma