Hans Franke wrote:
> For the records, Bletchley Park did not decode _all_ variants
> used during the war - but they did a prety good job for most
> of the stuff. The key was luck and a lot of good work.
And some moderate sloppyness in traffic handling by the German
command.
Different code schemes were used for different services, with
perterbation of the code schemes based on sensitivitiy. As a
consequence, the code schemes for the U-boat fleet were changed
quite often, while the code scheme used for harbor dispatches
remained static for prolonged periods of time.
Not surprisingly, harbor messages were decoded with little
trouble but offered little useful intelligence. Unfortunatly,
there were occasional messages which were shotgunned to multiple
services, which required encoding the same message under different
code schemes. Since the harbor code was compromised for long
periods of time, it provided the plaintext required for the
comparative cryptanalysis needed to reach the point where
traffic for other services could be "routinely" read.
--
Chris Kennedy
chris_at_mainecoon.com
http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97
Received on Tue Apr 04 2000 - 09:57:09 BST