Turing and origins of UKUSA
Caspar Bowden (travelling)
tharg at gmx.net
Sun Jun 24 19:50:17 BST 2012
On Turing Day +1 thought ukcrypto might enjoy this....
As list members no doubt recall al couple of years ago the UK National
Archives and the NSA simultaneously published a lot of material on the
UKUSA intelligence sharing agreements originating in WW2. However the
NSA published <http://www.nsa.gov/public_info/declass/ukusa.shtml>
significantly more (and different) material than released in UK
<http://www.nationalarchives.gov.uk/ukusa/>, and I was intrigued by
several aspects of the US "early papers 1940-1944"
<http://www.nsa.gov/public_info/_files/ukusa/early_papers_1940-1944.pdf>
Turing visited the US in November 1942, mainly to inspect US production
of bombes and have a shufti at US methods, but also to look at work in
Bell Laboratories on a new speech scrambler (likely what became SIGSALY
<http://www.nsa.gov/about/cryptologic_heritage/center_crypt_history/publications/sigsaly_story.shtml>).
However he was refused permission, and the "early papers" document the
US Army side of an escalating row which lasted until a prototype of
UKUSA was concluded in May 1943 (long before BRUSA in 1946)
The row was about the fact the US had become suspicious the UK was
holding back info on the Lorenz machine cipher (Tunny), although the US
had briefed the UK on the breaking of the Japanese PURPLE; also that the
UK wanted to keep control of Enigma exploitation because of worries
about security (reasonable because the US wouldn't tell them the
technology the US wanted to use to protect the dissemination of
decrypts); and that also the US Navy had got full access to UK decrypts
of German U-Boat Enigma but such agreements hadn't been reached with the
US Army for the European of African theaters.
Previous primary sources include Turing's initial report
<http://www.turing.org.uk/sources/washington.html> (Nov 28th) of his US
trip (released in 2004), which opened
I reached New York on Friday November 12th. I was all but kept on Ellis
Island by the Immigration Authorities who were very snooty about my
carrying no orders and no evidence to connect me with the F.O. They
considered my official's passport insufficient in itself. They asked me
very minute details about where I was to report etc. I think it might
have been better from a security point of view if I had been provided
with some kind of document of the kind they wanted, to say nothing of
the possibility that I might have been held until Stevens or somebody
identified me
..and continues with understated humour about the US approach to the
work. Turing is optimistic in the report that "all now seems to be well"
re: problem with visiting Bell Labs, but the "early papers" show that he
did not get permission until Jan 9th. His UK minder Maj.Stevens in a
covering note supports Turing skepticism and adds
. T
They (the US) are jokingly credited with wanting to take all traffic
that comes in and subject it immediately to every known process,
regardless that some of it may be P/L or in a cipher which they hold.
Amazingly Turing had not had instructions about whether he was allowed
to brief the US on Tunny (i.e. that by this time Tutte had reconstructed
the Lorenz machine purely with manual analysis), and evidently had to
keep this from the formidable US cryptographer Friedman (that must be
one of the all time cagey conversations)
What I haven't seen written up in any historical work since 2010 is that
relations became so bad in early 1943 that the UK were contemplating
cutting off the US from Continental Enigma (at least the US Army thought
so, and advised to call what they assumed was a UK bluff). The
corresponding documents on the UK side weren't released. The US Army
resented the fact they got trumped "in the Turing case" and that GCCS
had access to Churchill "and therefore to F.D.R" which they evidently
lacked.
There are several gems in the documents but favourite so far is :
"They (the UK) set forth the claim that in connection with this whole
subject of secret communications equipment, either voice scrambling,
cipher machines or anything of a similar nature, the specialists who are
experts in cryptanalysis or descrambling, should be in on the initial
development of the equipment. In that way these experts (according to
Tiltman et al) can point out weaknesses in design which could be
corrected in the development period. They claim that hundreds of man
hours could be saved if this procedure were followed rather than to have
a machine developed in one laboratory and then to give to another
laboratory the job of breaking down its traffic. In my opinion, this is
merely another attempt to gain access to technical information on our
cipher machines and ultra secret scrambling devices and is not a
plausible argument" (Dec 17 1942)
CB
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