Bill Tutte – The Lesser Known Codebreaker of Bletchley Park
billtuttememorialfund.wordpress.com
billtuttememorialfund.wordpress.com
I still remember that talk to this day. The actual content of the talk was very interesting (he talked about his work at Bletchley Park, coming to Canada, his research at UW), but what has stuck most in my mind all these years was what I can only call his aura. Even at 80+ years old, he was a captivating speaker and all ~ 20 of us kids in that class were slack-jawed, hanging off our seat, listening to every word, in awe of him and what he did, especially since he wasn't that much older than any of us were when he did it.
I later did work with mesh parameterization and was delighted to find out that his work was considered seminal (the planar embedding theorem and the so called "Tutte weights"). He made a lot of contributions and published a lot of material, so I guess I shouldn't be so surprised that my area of research intersected with his. It was a nice feeling to be able to reference him though.
To his memory.
The book talks about Tutte and Flowers and how they went about building the world's first true computer. It includes schematics and algorithms and other technical details of the machine. Actually, if you're old enough, you probably remember getting told in your first CompSci classes how computers were made up of I/O, a CPU and memory, which even by the 1980s seemed like a quaint way of viewing things. Reading Colussus for the first time, you really understand why they made the distinction in the textbooks. Just the machines to read and write to paper tape were incredibly complicated, and the speed that you could spool paper tape was a limiting factor in the early days. Indeed the first systems didn't really have a memory system, they had to keep re-reading data from tapes. The need to avoid that was the reason they invented memory in the first place - it sped up computer operations by orders of magnitude!
The book also covers in great detail how they went about intercepting the signals from the German High Command - which itself was a very modern digital modulation scheme that hadn't existed until them. The work of the signals interceptors was very impressive too, and run by the British Post Office, if my memory serves correctly :D
The transmission technology was RTTY (http://en.wikipedia.org/wiki/RTTY) which was active well before the Second World War. It would have sounded odd to Morse operators, but would have been recognizable and easily decoded as it is just FSK.
On the other hand, this had little impact on WWII as a whole, so it is not as important as the code breaking done at Bletchley park.
But Tutte worked on Lorenz, and this story is about Tutte and his work, and hence this story is not about Enigma.
His Wikipedia page is definitely worth a read to get a more balanced picture of the scope of his work:
The Lorenz cipher that Tutte broke is much closer to today's ciphers. It was a pseudo-random number generator whose output was XORed with the message to be enciphered (which had been converted to Baudot code): http://en.wikipedia.org/wiki/Lorenz_cipher
Very similar to RC4, for example.
And Lorenz worked by exploiting co-primality to achieve a long key stream.
http://en.wikipedia.org/wiki/W._T._Tutte#Doctorate_and_caree...