On Tue, 11 Jan 2000 09:11:04 -0500, Roger Turk wrote:
> Let me give you my idea of public key/private key usage by going back about
> 40 years. This is in the day where encryption was performed by mechanical
> crypto machines that had a number of rotors that could each be assembled in
> various manners. As the encrypter typed the plain text message, the crypto
> machine would generate a letter, increment the rotor so that if the same key
> was typed, a different letter would be generated. There would be literally
> thousands of ways the rotors could be assembled. The message would be the 5
> character group messages that Sam Heywood mentioned.
> Everybody had machines capable of decoding the message and anyone that had a
> radio receiver tuned to the proper frequency could receive the message,
> however, in order to decode the message, the recipient had to know how the
> rotors were assembled by the sender. Obviously, the sender could not send a
> plain text message giving instructions on how to assemble the rotors, yet,
> the sender had to tell the intended recipient how to assemble his/her
> rotors. This was done at the beginning of the message before the 5 character
> groups started, thus:
> 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
> code book, turn to the page for the date (and possibly time) the message was
> originated, and see that under rotor 1, ALPHA meant to assemble parts a, b,
> c, and under rotor 2, ROMEO meant to assemble parts e, f, g, etc. The code
> book page is the PRIVATE KEY. A person receiving the message who didn't know
> how to set up the rotors, i.e., did not have the PRIVATE KEY, would have to
> try the thousands of combinations of rotors in order to decode the message.
> The necessary parts are that everyone uses the same procedure to encrypt a
> message and that there is some way for the originator to tell the recipient
> how the message was encrypted.
> In using a secure site, the person sending his/her order would encrypt
> his/her order, possibly without knowing it, attach a PUBLIC KEY to it that
> would somehow tell the recipient what PRIVATE KEY was used to encrypt the
> message.
> PC Magazine had an article on how this was done several years ago and I can't
> remember exactly (or even generally) what they said.
> Hope this helps.
Roger.....greetings, fellow former Crypto Technician
gregy
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