VENONA decrypts

[John K. Taber]

Robert Reynard asks if there is a satisfactory explanation of why
one time pads were used more than once.

The answer is yes, as related in Haynes and Klehr's book on Venona,
for which the authors derived cryptographic info from Cecil Philips, an
NSA cryptanalyst now deceased.

The Russians didn't have enough one-time pad sheets. The War used up
what they had, and they couldn't produce more fast enough.

They did not duplicate pads, but sheets, which they interspersed with
unused sheets in new pads. That is, the new pads consisted of new sheets
of random numbers mixed with duplicated sheets. I suspect they
randomized
the order.

It was a makeshift due to the explosion of communications in the War.

John K. Taber

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