World War II mechanical encryption device

Engineers of the Bletchley Park computer museum recreated and presented the Tunny computer to the general public, which was used by the armed forces of the anti-Hitler coalition to decrypt Nazi radio messages during World War II. Work on the machine lasted three years and was seriously hampered by the fact that after the end of the war Tunny was dismantled, its components were lost, and the original drawings were destroyed or hidden, despite the fact that in May 1945 there were 15 operating devices.

To encrypt messages, the Germans used Lorenz's teleprinters with encryption prefixes, the results of which could not be decoded. However, as often happens, a key role was played by chance - on August 30, 1941, the German operator broadcast two almost identical messages (the first was delivered incorrectly, the second was slightly modified), using the same key twice. The radio intercept service worked perfectly and this error was enough for the head of the Bletchley cryptanalyst department, John Tiltman, so that the allies could successfully read German radiograms with Tunny until the end of the war.
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For clarification, thanks to the SCoon .

Under the cut more photo recreated Tunny.