Bletchley Park...

MaxHeadRoom

Joined Jul 18, 2013
22,641
I lived very close (Bletchley) at the time, of course, did not know what was going on! :oops:
I believe they used Gordon Welchman methods on tracking Osama Bin Laden.
 

Tesla23

Joined May 10, 2009
435
There is a documentary on Bill Tutte cracking Tunny which is well worth watching - History channel I think. Not quite as dry as the book, and with interviews with one of his co-workers. Studying pages of printouts of random letters looking for patterns, eventually deducing the wheel patterns of the encoding machine. The mistake by the operator in Athens and then the allies finally broke the code used by Hitler's high command. I think the fact that they cracked this code was classified at a higher level than enigma and was kept secret for longer, and that is why the story is not as well known, It's an amazing story.
 

nsaspook

Joined Aug 27, 2009
8,158
There is a documentary on Bill Tutte cracking Tunny which is well worth watching - History channel I think. Not quite as dry as the book, and with interviews with one of his co-workers. Studying pages of printouts of random letters looking for patterns, eventually deducing the wheel patterns of the encoding machine. The mistake by the operator in Athens and then the allies finally broke the code used by Hitler's high command. I think the fact that they cracked this code was classified at a higher level than enigma and was kept secret for longer, and that is why the story is not as well known, It's an amazing story.
https://forum.allaboutcircuits.com/...ectricity-and-electronics.177794/post-1614271

The five number code groups and spacing were still used when I was in Naval radio school after boot-camp.

The main lesson from that story was that simple XOR stream cipher are not secure. One Time Pad XOR ciphers are secure.
https://www.cs.sjsu.edu/~austin/cs166-spring17/slides/CS166-Day03+04-SymKeyCrypto.pdf

Systems designed in the 50's stream cipher digital systems using tubes had XOR Symmetric key-streams because of the limited complexity (Fibonacci form of a shift register) of circuits but they were never the final cipher-text result on the systems I know about and used. The general keying stream from one set of keying material (a key-card or jumper matrix) would not repeat for at least three days of continuous operation (keys were changed daily and old cards burned) while SI sensitive key-stream cards were cut in half inside the machine when the door opened. This was done to reduce Tunny operator mistakes.
https://en.wikipedia.org/wiki/KW-26
Because the KW-26 used a stream cipher, if the same key card was ever used twice, the encryption could be broken. To prevent re-use, the card was automatically cut in half upon reopening the CFD. As the units aged, the card reader contacts became less dependable, and operators resorted to various tricks, such as hitting the card reader cover with a screwdriver, to get them to work properly. Card readers were cleaned and the spring loading of the contacts checked as part of the routine maintenance of the device.
 
Top