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:
The Possibility of Secure Non-Secret Digital Encryption
J. H. Ellis, January 1970
Reference: (1) Final report on project C43. Bell Telephone
Laboratory, October, 1944, p.23.
The Bell lab paper appears not to be online.
Brian Durham notes that NSA has listed in its Open Door archive of
declassified crypto papers several of which refer to a Project
C-43 which investigated from 1941-1944 decoding of speech codes.
NR 4242 ZEMA172 35374A 19410521 PROJECT C-43 PRELIMINARY
NR 4243 ZEMA172 35375A 19411215 PROJECT C43 PRELIMINARY
AND PROGRESS REPORTS
NR 4675 ZEMA43 21276A 19430130 PROJECT C-43 CONTINUATION
OF DECODING SPEECH CODES
NR 3391 CBPM44 24215A 19441012 PROJECT C-43 DECODING
The date of the last, October 12, 1944, corresponds to that of the
Ellis citation. If this is the paper Ellis is referring to, it is worth
the dates of the earlier reports, two in 1941 and one in 1943.
Two other reports in the NSA archive may be related:
NR 2416 CBLM17 5452A 19420529 NRDC PROJECT C-32: AC
AND EC CASE NO. 22
NR 4674 ZEMA43 21275A 19420131 FINAL REPORT ON
PROJECT C-32 SPEECH PRIVACY DECODING, 1942
Brian Durham will get copies of the paper for putting online,
but that may take a while.
Meanwhile, we would appreciate hearing from anyone who
has read the papers or may have copies of them to share
Related: We have a three-year-old FOIA request to NSA for
The invention, discovery and development of non-secret
encryption (NSE) and public key cryptography (PKC) by
United Kingdom, United States, or any other nation's
intelligence and cryptology agencies, prior to, parallel with,
or subsequent to, the PKC work of Diffie-Hellman-Merkle.
NSA has recently said that some responsive information
may be released in the near future, although it is not clear if
that is weeks or months or years away.
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