The Enigma of the Germans

While at the university, I studied a little bit about cryptography where I learned about the Enigma machine in pretty good detail. The Enigma machine was an easy functional encryption device used heavily by the Germans during World War II to communicate - from bases, ships, and submarines. This website covers everything you ever wanted to know about the Enigma machine, particularly things the Germans did incorrectly that enabled the British to crack the code more easily.

Entry points for encrypting the messages.

A) message keys

The operator has to select 3 letters randomly But sometimes they use "AAA", "BBB" or the diagonals of the keyboard (QFL), any abbreviations, his own initials or any dirty words.

A German operator in southern Italy has used frequently his girlfriend initials CILLI and the British called such bad and easy to guess keys CILLIES (sometimes also called Sillies = Dummheiten)

B) A letter never enciphers to itself.

If you type a "A" you will get any letter from B-Z, but never an ``A''. The sequence : AAAAAAA may be XUVGFXY without any ``A''.

A tired German operator has been told to send out dummy messages and he typed only the last letter of the keyboard : ``L''. The British code breaking expert immediately recognized the missing ``L'' in the enciphered message and they got a very big crib (see below).

     [cipher]DAOACQAOFFNNHDYAPSGZHEPTWCFZEPAARVDZOSWJDHXMESGWSGRQYOZ
     [plain]LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL

C) CRIBS (=Eselsbrücke)

A crib is a part of the plain text which is known to correspond with a part of the code.

Knowing the source of the message (army, navy) you can guess the meaning.

For instance most of the messages start with AN (e.g AN GENERAL...) . This was coded as ANXGENERAL

Another possibility was : AN DIE GRUPPE (to the group) The code breakers tested the first 3 letters for ANX.

KEINEBESONDERENEREIGNISSE (no special occurrences, nothing to report) could be a part of the message This crib was placed above the enciphered text and moved left and right until no letter enciphers to itself.

D) KISS

A kiss is a message that has been sent previously on a lower level radio net, which has already been enciphered. This means, the same message was send twice, but with different systems.

The British forced such messages by doing any military activity and then they waited for the messages...

E) Capturing codebooks and secret material

Found codebooks of sunken submarines or captured weather ships and military bases were also very helpful and provided the British with Enigma ground settings for some months and abbreviations for weather reports, which could be used as cribs. Some of these keys has also been used by the U-Boots.