November 16, 2007
German Radio Amateur wins Colossus Code Cracking Contest
John Dorsey
The Cipher Challenge held by a Bletchley Park team invited amateurs to compete against a vintage replica Colossus in decoding a message in the WWII-era Lorenz SZ42 cipher.
Joachim Schüth, a programmer in Bonn, Germany has won the Colussus Cipher Challenge by being the first to decrypt an message encoded in the World War II-era
Lorenz SZ42 cipher. The Cipher Challenge was held by a team at the National Museum of Computing at Bletchley Park in the UK. The team, led by Tony Sale, spent over a decade rebuilding a working replica of Colussus Mark 2, the British computer used to break the German Lorenz cipher in WWII. To celebrate the completion of the rebuild, the museum held the Cipher Challenge, sending an encoded message from Germany to see how quickly the new Colussus could decode the message.
Amateur radio operators were also invited to participate in the challenge, and Joachim took them up on it. He wrote his own software in Ada and has posted his source code online, along with details of how he was able to determine the cipher in 46 seconds. He relied on the radio transceiver of a local ham radio club and decoded the message on his laptop. Naturally, this gave him an advantage over the Bletchley Park team using the Colussus, which takes hours to decode the cipher.
According to a BBC News report, a separate team at Bletchley Park also ran a "virtual Colossus" on a laptop, which beat the vintage iron as well. Cryptographic purists point out that newer digital computers are faster at breaking ciphers, but the older analog computers provide warmer decryption and better fidelity, particularly when decoding messages in Jazz.
The Museum provides the Virtual Colussus software online as well as the ciphertext from the messages so that future cryptanalysts can attempt to break it.
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