M4 Message Breaking Project

The M4 Message Breaking Project is trying to break three last unencrypted Enigma messages, one message has already been broken.

The fact that it takes 100 celeron processors 4 days to walk the key space demonstrates that the NAZI faith in the enigma machines was not entirely misplaced. The codes were broken because the machine had two relatively minor weaknesses and because the cipher clerks were sloppy.

It appears that Michael Smith's excellent Station X history of the Ultra project is out of print. But this book 'codebreakers' looks interesting, a collection of personal accounts of the project by the codebreakers themselves.