Ultra

Ultra

Jump to: navigation, search
For other uses, see Ultra (disambiguation).
The Enigma cipher machine Enigma-logo.jpg

* Enigma machine
o Enigma rotors
* Breaking Enigma
o Polish Cipher
Bureau
+ Doubles
+ Grill
+ Clock
+ Cyclometer
+ Card catalog
+ Bomba
+ Sheets
o Bletchley Park
+ Banburismus
+ Herivel tip
+ Bombe
+ Hut 6
+ Hut 8
o PC Bruno
o Cadix
* Ultra

This box: view • talk • edit
An Enigma-machine rotor

Ultra (sometimes capitalised ULTRA) was the name used by the British for intelligence resulting from decryption of encrypted German radio communications in World War II. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources. The name arose because the code-breaking success was considered more important than the highest security classification available at the time (Most Secret) and so was regarded as being Ultra secret.

Much of the German cipher traffic was encrypted on the Enigma machine, hence the term "Ultra" has often been used almost synonymously with "Enigma decrypts". However, in terms of the intelligence value, Lorenz SZ 40/42 decrypts were more important.[1]

Polish reconstructions of the Enigma machine and techniques for decrypting ciphers produced on it were presented as a gift by Polish Military Intelligence to their French and British allies in Warsaw on July 26, 1939, just five weeks before the outbreak of World War II. It was not a moment too soon. Former Bletchley Park mathematician-cryptologist Gordon Welchman has written: "Ultra would never have gotten off the ground if we had not learned from the Poles, in the nick of time, the details both of the German military... Enigma machine, and of the operating procedures that were in use."[2]

Until the name "Ultra" was adopted, there were several cryptonyms for intelligence from this source, including Boniface. For some time thereafter, "Ultra" was used only for intelligence from this channel.

F.W. Winterbotham, in The Ultra Secret (1974), quotes the western Supreme Allied Commander, Dwight D. Eisenhower, as at war's end describing Ultra as having been "decisive" to Allied victory in World War II.[3]