LECTURE BY SIR HARRY HINSLEY ON SIGINT

[John Pettifer]

Bill Grayson makes a good point about the delays in getting WWII
Enigma intercepts to Bletchley Park.

In fact, Chicksands was the nearest Y station to Bletchley Park. It
would have taken over 2 hours to courier intercepts from Beaumanor
(Army) and perhaps 3 hours from Winchester (Navy).  In retrospect, it
does seem strange that these delays could be tolerated. There were of
course some teleprinter circuits, but this involved re-keying and
availability was limited. It seems pretty clear that the bulk of
intercepts went by motorcycle.

Incidentally (& just to clarify),  the bombes did not to do the actual
decryption - they were used to work out the Enigma daily
configurations using cribs derived from selected messages. The
decryption was done by keying the messages into Enigma emulators -
usually modified TypeX machines.

Regards to all,

John Pettifer.

----- Original Message -----
From: "bill grayson" <bill.grayson at auatac.com>
To: <INTELFORUM at his.com>
Sent: Wednesday, April 14, 2004 2:22 PM
Subject: RE: LECTURE BY SIR HARRY HINSLEY ON SIGINT


>  Thanks to John Bugler for the reprint of Sir Harry Hinsley's
interesting
>  WWII SIGINT remarks.  Sir Harry misspoke, technically, on what might
be seen
>  by some as a very minor point; however, it pertains to a
debilitating
>  intelligence problem that bedevils us to this day.  A solution
remains
>  elusive.
>
>  Sir Harry commented (concerning  German Enigma decrypts): " . . .
the whole
>  of the rest of that 24 hours' signals from the moment you broke the
[Enigma]
>  key for the day, the setting for the day, would be read
instantaneously, as
>  soon as the message was intercepted it would be decrypted."
>
>  Sir Harry didn't mean, "as soon as the message was intercepted."
>
>  German Luftwaffe Enigma messages were intercepted at RAF Chicksands,
just
>  south of Bedford, by Morse wireless operators, furiously copying
5-letter
>  codegroups with pencils on pre-printed message forms.  Throughout
the war
>  and long past 1945, none of these "Y" Service  wireless operators
knew what
>  plaintext lay under the Enigma ciphertexts.  Message forms were
couriered
>  from Chicksands to Bletchley, a 45-minute ride in the best weather,
by
>  motorcycle dispatch riders.  At Bletchley, the codegroups copied in
pencil
>  had to be manually transcribed for Bombe processing.  No British
intercept
>  stations were capable of decrypting Enigma messages; none could be
decrypted
>  as soon as intercepted.

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