Trustworthy contacts

[John R T Brazier]

George Foot Said:


'A cryptosystem common to a  number of nations is impractical unless
those nations are fully integrated politically and have a discipline
which allows a full investigation by any one of them into lapses which
occur in any  other of them  --- a state of intimate political union for
which there is no prospect at the present time ? '



To support this apposite comment, I can only quote from Hinsley et al's
'British Intelligence in the Second World War', Vol 2, Appendix 1 Part (i),
p636, with special reference to the Admiralty codes (as it was the first
example I could find, stuff in square brackets mine):

'Before the war no consideration had been given to the provisions of secure
communications between the Royal and United States Navies. When the need for
this could be seen as a possibility in late 1940, the Admiralty, with the
agreement of the US Navy Department, set aside one of its own reserve Naval
Cypher Basic Books, No 3, for this purpose and produced long subtractor
tables for use with it. These were brought into use in June 1941 for use by
the British, US and Canadian Navies in the Atlantic, for which purpose, for
fear of unwieldiness, it was used to begin with without the improvements
which had been applied to Naval Cyphers No 2 and No 4. This had serious
consequences from October 1941, when the cypher began to carry an increasing
amount of traffic. In January 1942, having realised that Naval Cypher No 3
had become the most important cypher for communications concerning
arrangements for convoys and stragglers in the Atlantic, the B-Dienst [a
German cypher bureau] concentrated most of its resources against it. By
February 1942 it had reconstructed the book ...'

B-Dienst read the cypher until 15 December 1942. So three years into WWII,
Germany was reading UK/US Naval communications because, basically, nobody
had done anything about Allied secure communications before the war. The
Combined Cypher Machine, which was the ultimate Allied Naval system [that
was never broken by the Germans] only really started being used in November
1943 for Atlantic communications.

Cheers,

John B