Apparently a number of German code systems kept on being used after WW2 (and by nations other than Germany). At least part of the Bletchley Park inventory ended up in GCHQ were the machines were used into the '70s.
The Bletchley Park guys figured out how the Lorenz machines worked by decoding messages by hand. They then built the Tunny machines to emulate a Lorenz machine. The actual codebreaking was mostly done by a Heath Robinson machine (or later, a Colossus), this yielded the correct wheel settings. These settings were then entered in the Tunny machines, and these could be used to decrypt the day's Lorenz traffic.
I was at Bletchley Park last year and saw the Tunny exhibit. Didn't realize that they were still working on the rebuild.
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Apparently a number of German code systems kept on being used after WW2 (and by nations other than Germany). At least part of the Bletchley Park inventory ended up in GCHQ were the machines were used into the '70s.
The Bletchley Park guys figured out how the Lorenz machines worked by decoding messages by hand. They then built the Tunny machines to emulate a Lorenz machine. The actual codebreaking was mostly done by a Heath Robinson machine (or later, a Colossus), this yielded the correct wheel settings. These settings were then entered in the Tunny machines, and these could be used to decrypt the day's Lorenz traffic.
I was at Bletchley Park last year and saw the Tunny exhibit. Didn't realize that they were still working on the rebuild.