An idea came to me today for a protocol for exchanging keys point-to-point (inspired by the Robert Cain messages). The protocol is a just combination of the Interlock Protocol described on page 44 of "Applied Cryptography" and Diffie-Hellman, describe on page 275.
Keeping with the terminology of the book, Alice will attempt to exchange a key with Bob, and Mallet will attempt to sit in the middle without being detected.
As has been demonstrated in the past, I haven't read a lot of the cryptography papers that are out there, so for all I know, this is a well known protocol (or simple variation). However, I haven't seen it, and it seems interesting. Anyways, on with the show...
1) Alice sends Bob her public key. (ala Interlock Protocol)
2) Bob sends Alice his public key.
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Jim_Miller@suite.com
Could someone briefly explain the Interlock Protocol, I don't have "Applied Cryptography". However, it seems that Jim's protocol depends on the Interlock Protocol guaranteeing that Alice really gets Bob's public key and vice versa. Otherwise, it seems that Mallet could give each of Alice and Bob his (or is that a feminine name?) public key, go through Jim's protocol with each party, then just translate every message from cipher-text to clear-text then back to cipher-text using the key for the other half of the conversation. tim