Pre-cursor to Non-Secret Encryption

[Dave Howe]

John Young wrote:
> James Ellis, GCHQ, in his account of the development of non-secret
> encryption credits a Bell Laboratories 1944 report  on "Project
> C-43" for stimulating his conception:
However the concept seems familiar enough - unless I am missing something, a
PRNG (n for noise rather than number this time) in sync with a similar PRNG
at the recipient end is mixed with the plaintext signal to give a
cryptotext; the matching unit subtracts the same values from the received
signal to give the original plaintext.  If it were digital we would probably
xor it :)


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