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4 January 1996
This letter originally appeared in Cryptologia October 1996;Volume XX, Number 4.
Dear Editor
The Bletchley signals used for my counts were from reel 317 (5.8.43-10.8.43, JP 1-500) for the 6 Aug 1943 sample, and from reel 336 (12.11.43-18.11.43, JP 9501-9599) for the 13 Nov 1943 sample. The 6 Aug messages were JP 55 (060006Z/8/43) through JP 163 (062319Z/8/43), and the 13 Nov messages were Jp 9591 (130003Z/11/43) through JP 9676 (13,2312Z/11/43). Especially long Bletchley messages in these periods were JP 100 (two parts totaling about 1500 letters in English), and JP 9645 (three parts totaling over 2000 letters in English.)
As Mr. Erskine suggested, the vast majority of these messages deal with naval subjects, although some (e.g. JP 9599) deal with railroad interdiction and a number of them deal with damage to airfields. I was unaware that these messages from Bletchley summarized multiple Enigma intercepts, and I am glad to have Mr. Erskine's clarification of this point.
If any reader could direct me to a cache of Enigma ciphertext and (German) plaintext I would be very appreciative ... using guesses and surrogates for this traffic is quite unsatisfying.
An additional note on the three ciphers Mr. Erskine provided, for the edification of anyone accepting the challenge: Frode Weierud said about these messages [private e-mail message I Aug 1994].
The message format is such that it is 100% sure that these three messages are Enigma or RHV (Reserve Hand Verfahren) which was the backup hand cipher used in case something happened to the Enigma machine itself or they had lost or had to destroy their Enigma keys for some reason or another. As RHV were rarely used I think we can assume with a very [high] probability that these are genuine Naval Enigma messages. As I don't know where they were intercepted it is impossible to make any guess about the key in use or if they are enciphered on a three rotor or a four rotor machine.
Regards
Jim Gillogly
Added in proof from Ralph Erskine "Having seen James Gillogly's letter of 4 January, it is almost certain that the translations to which he refers are merely Bletchley Park summaries of decrypts and not the decrypts themselves, The prefix "JP" cited by him was used by the Special Communications Units and Special Liaison Units for signals sent to various Allied Commands from 5 August to 18 November 1943 (cf his dates): F. H. Hinsley et al. British Intelligence in the Second World War, 3(l) (London, 1989), p. 975. They are now on files DEFE 3/871 to 890 in the Public Record Office, Kew, London. Even the signals on naval topics will not contain the verbatim text of German signals unless they are identical to the decrypts in the ZTP[G or M] series, which is most unlikely, as that would have been a breach of security. Decrypts as such were virtually never sent to Commands, even in the Royal Navy. The only exceptions were when Prime Minister Winston Churchill gave a direct instruction to that effect."
