On Tue, 11 Jan 2000 20:42:14 -0500, Roger Turk wrote:
> Sam Heywood wrote:
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 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.
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 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.
If a code book were captured or otherwise compromised, then the enemy would
have the PRIVATE KEY. Once in possession of the PRIVATE KEY, then the PUBLIC
KEY would make perfect sense to the enemy. "ALPHA" and the phonetics that
follow, do not tell me anything, but if I had the code book I would probably
be able to figure out how to set up the ciphering gears and wheels. For that
reason, I cannot understand why the PUBLIC KEY would be transmitted in the
clear. It would make much more sense to simply provide instructions in a
pre-mission briefing as to how to apply different ordering schemes to the
ciphering wheels and gears depending on the date/time group of the message.
> 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.
Yes, it is indeed meaningless to one who does not have the PRIVATE KEY.
If an enemy were to come into possession of the PRIVATE KEY, even this key
might not be very helpful to him unless he also had the so-called PUBLIC KEY.
Therefore, to provide for a higher level of security, there should be no
PUBLIC KEY. Communicators being deployed into the operational area should
simply commit to memory some instructions concerning how the ciphering wheels
are to be re-arranged according to the date/time group. Under this kind of
system, the code might remain unbroken unless the enemy should capture a
ciphering machine and a code book and a communicator who could be coerced
into cooperating.
> 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.
Of course I agree. The receiver must know how to assemble the rotors for
*each* message, and both the sender and receiver should use a different
assembly for each message. To accomplish this, there should be a different
scheme for the rotor assemblies for each date/time frame. The different
setups should be memorized prior to deployment. The different setup
arrangements could be recalled in accordance with the aid of an easy to
memorize secret rhyme or anagram. Hence, no need for broadcasting a PUBLIC
KEY.
> *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.
That is indeed the way things ought to be.
> I hope that this answers your concerns.
I think i'm beginning to understand the system better. Thanx.
Sam Heywood
> Roger Turk
> Tucson, Arizona USA
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