[rc5] Enigma and Purple (was Re: One Time Pad)
gindrup at okway.okstate.edu
Tue Oct 28 15:10:29 EST 1997
Sure. Where's your address?
Enigma was broken initially through exhaustive (mostly manual)
search and then "human factors" were used to continue decoding. In
particular, individual operators had habits in selecting "key phrases"
that could be used to (with very high accuracy) predict a new
The exhaustive search was aided by the knowledge that the wheels
were "linear" in that each character was mapped to and from one and
only one character. The other aid was that the set of wheels was
mostly fixed (except late in the war and on the U-Boats).
Whenever the encryption key was changed to something unguessable, a
large brute force effort was (re-) started to extract the key.
The Enigma code was more like a simple substitution code with a
highly alterable substitution rule. This is why brute force attacks
were conceivable. It's trouble was that an entire sequence of
(similarly encoded) messages made a good statistical sample from which
to apply letter frequency analysis and similar standard tools.
-- Eric Gindrup ! gindrup at Okway.okstate.edu
______________________________ Reply Separator _________________________________
Subject: [rc5] Enigma and Purple (was Re: One Time Pad)
Author: <rc5 at llamas.net > at SMTP
Date: 1997/10/27 15:23
This reminds me a lot of the German Enigma and Japanese Purple
encryption schemes. They used wheeels (4 or 5) which translated what
one letter should be into another. Then after each letter was encrypted
they would move the code wheel to the next notch which would switch the
translation tables for the characters. This sounds like it would
duplicate the otp if the code wheel combinations were longer than the
message and if new code wheels were issued once they were used up
right? Does anyone know the particulars on how those two systems worked
and how we managed to crack them encryption scheme? From what I
remember we managed to crack one of the systems before we actually got
a hold of the code wheels. Is this because in actuality the code wheel
combinations weren't longer than the message or that the wheels weren't
R a n j i t A n n a m a l a i
Page me at 1-888-pagoo-44 id:4088935 http://www.netwalk.com/~meena
To unsubscribe, send email to majordomo at llamas.net with 'unsubscribe rc5' in the
To unsubscribe, send email to majordomo at llamas.net with 'unsubscribe rc5' in the body.
More information about the rc5