Submission + - Alan Turing developed a portable voice encryption device (popularmechanics.com)
smooth wombat writes: Alan Turing, one of the more famous people who worked at Bletchley Park to decipher the German Enigma coding machine, was also working on a separate project. His private papers, known as the Bayley papers for his assistant Donald Bayley who held onto the papers until his death in 2020, reveal Turning had produced a working model of a portable voice encryption device. He even demonstrated it by using a Winston Churchill speech recording.
“Weighing just 39 kg, including its power pack,” Copeland summarizes, “Delilah would be at home in a truck, a trench, or a large backpack.”
Turing’s work at Bletchley Park actually informed the Delilah experimentation he was doing at Hanslope Park, and not just because he used Red Forms, the Army-issue sheets Hanslope staffers were meant to use to alert Bletchley staffers to enemy signals, as his personal scrap paper for Delilah experiments. He drew inspiration from one of the German cipher machines they had decoded at Bletchley; not the famed Enigma machine, but rather the SZ42. While the former relied on Morse Code, the latter utilized a 5-bit telegraph code, which Copeland notes “was a forerunner of ASCII and Unicode and is still used by some ham radio operators.”
The SZ42 produced an obscuring key of telegraph characters, with an identical key produced to both the sender and receiver. If it could be done for text, Turing reasoned it could be done for sound as well.
This is the part of the story where one might say “Well, I’ve never heard of Alan Turing’s voice encoder, so the experiments must have failed.” But remarkably, they didn’t. Turing and Bayley actually did create their Delilah, and even demonstrated it using a recording of a Winston Churchill speech, “successfully encrypting, transmitting, and decrypting it.”
Instead, the reason Delilah fell to the wayside of history isn’t because it was a failure, but rather because it simply wasn’t needed anymore. By the time Turing had built and demonstrated his device, the war was over. What good was a portable voice encryptor if you had no major enemies trying to intercept your calls, the government reasoned. So funding for the project stopped, and Turing’s two-year experiment ended with a whimper. Turing’s time as an electrical engineer at Hanslope Park became a footnote in his story, if even that.
“Weighing just 39 kg, including its power pack,” Copeland summarizes, “Delilah would be at home in a truck, a trench, or a large backpack.”
Turing’s work at Bletchley Park actually informed the Delilah experimentation he was doing at Hanslope Park, and not just because he used Red Forms, the Army-issue sheets Hanslope staffers were meant to use to alert Bletchley staffers to enemy signals, as his personal scrap paper for Delilah experiments. He drew inspiration from one of the German cipher machines they had decoded at Bletchley; not the famed Enigma machine, but rather the SZ42. While the former relied on Morse Code, the latter utilized a 5-bit telegraph code, which Copeland notes “was a forerunner of ASCII and Unicode and is still used by some ham radio operators.”
The SZ42 produced an obscuring key of telegraph characters, with an identical key produced to both the sender and receiver. If it could be done for text, Turing reasoned it could be done for sound as well.
This is the part of the story where one might say “Well, I’ve never heard of Alan Turing’s voice encoder, so the experiments must have failed.” But remarkably, they didn’t. Turing and Bayley actually did create their Delilah, and even demonstrated it using a recording of a Winston Churchill speech, “successfully encrypting, transmitting, and decrypting it.”
Instead, the reason Delilah fell to the wayside of history isn’t because it was a failure, but rather because it simply wasn’t needed anymore. By the time Turing had built and demonstrated his device, the war was over. What good was a portable voice encryptor if you had no major enemies trying to intercept your calls, the government reasoned. So funding for the project stopped, and Turing’s two-year experiment ended with a whimper. Turing’s time as an electrical engineer at Hanslope Park became a footnote in his story, if even that.
