Britannica Sources used in this answer

What role did Alan Turing play in the effort to break Tunny messages?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

The Colossus computer at Bletchley Park, Buckinghamshire, England, c. 1943. — Colossus Funding for this code-breaking machine came from the Ultra project.

In 1942, Alan Turing devised the first systematic method for breaking messages encrypted by the German cipher machine known as Tunny.

While Turing is widely recognized for his work on the Enigma cipher and the development of the Bombe, his contribution to the Tunny effort was significant: his method for deducing the letters of the "key" used to encrypt these messages served as the code breakers' primary weapon against the system for many months.

However, as the volume of intercepted Tunny transmissions increased and the Germans enhanced their security, manual decryption using Turing's method became too slow. This limitation necessitated the development of high-speed analytic machines, eventually leading to the creation of Colossus, the world's first large-scale electronic computer, which was designed to automate the Tunny code-breaking process at electronic speeds.