Alan Turing's Remarkable, Nearly-Forgotten Voice Encryption Device
The article details Alan Turing's development of the Delilah, a secure voice encryption system created after World War II. Though technically successful, the device was nearly forgotten because the British government lost interest in portable voice encryption after the war. The piece highlights Turing's innovative work beyond his famous codebreaking at Bletchley Park.
Background
- Alan Turing is best known for breaking the Nazi Enigma code and pioneering computer science, but he also worked on secure voice communications during WWII after his codebreaking stint at Bletchley Park.
- The "Delilah" system was a portable voice encryption device Turing built at Hanslope Park in 1943–44. It encrypted speech by mixing it with a random noise key, making intercepted calls unintelligible.
- Delilah was successfully tested but never deployed in the field—partly because the war ended and partly because it required synchronized, high-quality playback equipment that wasn't practical for battlefield use.
- The project was classified and largely forgotten, with most documentation lost or destroyed. This article draws on recently rediscovered notebooks and engineering notes that shed new light on Turing's hands-on hardware work.