TheCodeBreakers
major share of credit for solving the edition of the fleet cryptographic
system then in force. Collaboration was too intimate. A possibility raised
in a discussion between Dyer and Wright might be developed into a
probability by a check of messages in Washington and verified by a new
intercept at Colombo.
Meanwhile, the Japanese—who had no suspicion of all this activity—
felt a vague unease at the extreme length of service of this code. A new
edition, which would be called JN25c by the Americans but was called
the Naval Code Book D by the Japanese, was to be placed in service April
1. But administrative confusion in the Navy libraries, which had custody
of the codebooks, plus difficulties in physically distributing the books by
destroyer and airplane to moving ships and widely dispersed
installations, forced a postponement to May 1. Consequently, the
American cryptanalysts could tunnel ever more deeply into JN25b.
annaabi.ee 
