Sam Heywood wrote:
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On Tue, 11 Jan 2000 09:11:04 -0500, Roger Turk wrote:
> ALPHA ROMEO ALPHA CHARLIE HOTEL ... (etc.)
> This is the PUBLIC KEY. Everyone who received the message received the
> Public Key. The people to whom the message was intended would pull out
their
Why should the transmitting station broadcast the PUBLIC KEY? The reference
numbers for each specific set of instructions for the ciphering gear setup
for any given date/time group should have been previously provided to all
operators during the pre-mission briefing. In case a code book and a
ciphering machine were compromised, the enemy would be able to exploit
such captured material to his maximum advantage simply by setting it up in
accordance with all the hints freely provided in the PUBLIC KEY that is being
broadcast in the clear.
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Sam,
What does "ALPHA" tell you? What "hints" are in "ALPHA?" If you can make
something of it other than a name for a Greek letter and the phonetic for the
letter "A" then all the more power to you.
But, if this is in the first line of an encrypted message, and you have the
PRIVATE KEY, the PRIVATE KEY will tell you how to assemble the first rotor in
the encrypting/decrypting machine. Without the PRIVATE KEY, "ALPHA" is
meaningless.
The same with "ROMEO," "ALPHA," "CHARLIE," "HOTEL" ...
The second "ALPHA" together with the PRIVATE KEY would tell you how to
assemble the third rotor, and, more than likely, it would be entirely
different than the assembly of the first "ALPHA."
*ALL* encrypted messages may (more likely) have been encrypted with
different rotor assemblies. Therefore, the sender has to let the receiver
know how the rotors are assembled for *each* message. Having all encrypted
messages encrypted with the same rotor setup is asking for nothing but
trouble.
*ALL* units don't have every PRIVATE KEY. Front line units that are subject
to capture have only the minimum number of PRIVATE KEYS necessary to perform
their task. Rear elements and commanders have a larger set of PRIVATE KEYS,
and so on. There are procedures in place in case there is compromise or
possible compromise.
I hope that this answers your concerns.
Roger Turk
Tucson, Arizona USA
