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Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

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Re: Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

#2

Post by ColinWright »

How I wish I could upvote this more than once. One of my heroes - wonderful mathematician, phenomenally clever, incredibly modest.

His Wikipedia page is definitely worth a read to get a more balanced picture of the scope of his work:

https://news.ycombinator.com/item?id=5779247

Re: Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

#3

Post by jgrahamc »

ColinWright wrote: post #2

How I wish I could upvote this more than once. One of my heroes - wonderful mathematician, phenomenally clever, incredibly modest. His Wikipedia page is definitely worth a read to get a more balanced picture of the scope of his work: https://news.ycombinator.com/item?id=5779247

Agreed. And also everyone talks about Enigma but in many ways it was the end of the line of cryptosystems.

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.

Re: Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

#4

Post by antimagic »

There's a good book out - http://www.amazon.com/Colossus-secrets-Bletchley-code-breaki...

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

Re: Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

#6

Post by jgrahamc »

antimagic wrote: post #4

There's a good book out - http://www.amazon.com/Colossus-secrets-Bletchley-code-breaki... 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 m…

If my memory serves, the German High Command were using teleprinters and were sending the teleprinter signals via radio. This did sound totally different from Morse (which was used for other signals, such as those encrypted with Engima), but I don't think this was very new.

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.

Re: Bill Tutte – The Lesser Known Codebreaker of Bletchley Park

#8

Post by antimagic »

jgrahamc wrote: post #6
antimagic wrote: post #4

There's a good book out - http://www.amazon.com/Colossus-secrets-Bletchley-code-breaki... 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 m…

If my memory serves, the German High Command were using teleprinters and were sending the teleprinter signals via radio. This did sound totally different from Morse (which was used for other signals, such as those encrypted with Engima), but I don't think this was very new. The transmission technology was RTTY ( http://en.wikipedia.org/wiki/RTTY ) which was active well before the Second World War. It would have sound…

It's been a while since I read the book, but I thought the modulation scheme was a form of QAM, which was new at the time. The book certainly emphasizes that it took the interceptors quite some time to realise what they were seeing. Still, my memory of the details is a bit fuzzy, and I know that you have researched this area quite extensively, so I defer to greater knowledge ;)
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