[HN Gopher] The Spy Among Us (2015)
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       The Spy Among Us (2015)
        
       Author : collapse
       Score  : 17 points
       Date   : 2022-05-07 04:34 UTC (1 days ago)
        
 (HTM) web link (magazine.utoronto.ca)
 (TXT) w3m dump (magazine.utoronto.ca)
        
       | ncmncm wrote:
       | The only way it could have been unbreakable would be if it relied
       | on one-time pads.
       | 
       | Leo Marks, in England, championed a one-time pad system for field
       | agents in occupied areas.
       | 
       | There was a one-time pad audio telephone system relying on
       | phonograph record copies at bot ends, physically broken after
       | use. Churchill and Roosevelt used it.
        
         | sshumaker wrote:
         | It did use one time pads:
         | 
         | Two paper tape readers are mounted in front of the 700 Unit at
         | the top. One is a 5-level tape reader, which is used to read
         | the plaintext (when used offline). The other one is a 6-level
         | reader which is used to read the keystream tape. The signals of
         | both readers are 'mixed' in the 804 unit by means of modulo-2
         | addition (XOR).
         | 
         | ...
         | 
         | For proper security it is important that the keystream tape
         | contains a sequence of evenly spread truely random characters.
         | Producing such a random keystream was a major challenge during
         | WWII.
         | 
         | When the need for keystream tapes increased during the course
         | of war, the manual production was replaced by electromechanical
         | methods. The machine that was used for the production of Rockex
         | key tapes was codenamed DONALD DUCK, possibly because it speaks
         | gibberish [3]. It wasn't before the application of a noise
         | source however, that truely random key streams were produced.
         | In the UK, a noise generator with five flip-flops was developed
         | at GCHQ just after WWII by former GPO-engineer Don Horwood, who
         | had also worked on Colossus at Bletchley Park.
         | 
         | ...
         | 
         | Furthermore, he allowed only two identical tapes and instructed
         | them to be both destroyed immediately after use. This way the
         | machine became a real One-Time Pad system.
         | 
         | From https://www.cryptomuseum.com/crypto/uk/rockex/index.htm
        
       | winnipeg wrote:
        
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