Signals Intelligence Focus/Interest Group


The Signals Intelligence (SigInt) focus group is interested in the processes and tools used to gather intelligence from radio and radio-telegraphy  (signals) and the influence of this intelligence on the conduct and outcome of WW2.  The use of codes, ciphers, cipher machines (like Enigma) and related systems to encrypt and secure information; the corresponding analysis by the other side to untangle those encoded or enciphered messages, and the distribution and use made of such intelligence.

Codes or ciphers have been used for thousands of years because someone was always trying to keep someone else from knowing what they were transmitting.  When the only form of transmission was writing, codes and ciphers were relatively simple.  As technology produced the telegraph and the radio, the ability to transmit information quickly over long distances jumped dramatically.  But it also meant that virtually anyone could intercept the message without either the sender or receiver knowing it.  So, the need for better codes and ciphers arose.  With each improvement in codes and ciphers, those charged with the responsibility of breaking the codes and ciphers had to get smarter and better -- and they did.

Work In Progress


The broad availability of radio communications and and electro-mechanical enciphering machines (like Enigma, Lorenz, the Japanese type 97 machine and others) during WW2 provided both diplomats and the military with seemingly secure and rapid communications.  But were they?  As it turns out, when properly used, the new enciphering systems were virtually unbreakable.  But people have to use them and people are not always as diligent and careful as they should be. 

Glossary of Terms  (this glossary is broader than codes and ciphers circa WW II)

Recommended Books


Mechanical and electro-mechanical cipher machines like Enigma, Lorenz, M209, etc can be simulated on the computer with quite accurate and realistic results.  Computer based simulators range from quite simple to quite elegant.  Links to available simulators can be found here


Links (to relevant sites)


CIA Factbook