[GreenKeys] Crypto story

[Duncan Brown]

Great story!

On 11/23/2018 21:04, Jim Haynes wrote:
>
> This is in the book "Old Wires and New Waves" by Alvin F. Harlow, mid
> 1930s.  All about the state of communications systems when it was 
> written.
>
> He says that at the end of WW-I the Signal Corps had a show-and-tell for
> the press of all the neat stuff developed during the war.  One of which
> was the Vernam cipher machine.  It uses a one-time tape of random key to
> produce an unbreakable message.  This involves doing an exclusive-OR
> operation on each of the five code levels between the message tape and
> the key tape.
>
> Except for the demo they did some leg pulling.  The told the press they
> had developed a machine that could translate French into English and
> vice versa.  Demonstrated by putting a tape of English text in as the
> message tape and having the French equivalent come out the printer.
>
> Of course what they had actually done was make a piece of English text
> and then make a translation into French such that both contained exactly
> the same number of characters.  Then they had hand-constructed a key tape
> such that each character from the English tape was converted to the
> correct character for the French translation.  And if they put the French
> text as input it would be converted back to English.
>


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