> Perhaps you should look at Shamir's no-key protocol. This does exactly > what you want. Try looking at page 500 in Handbook of Applied Cryptography > (http://www.cacr.math.uwaterloo.ca/hac/) (you should really read chapter > 12 of this book if you're interessed in Key Establishment Protocols). > This protocol is similar to Diffie-Hellman but exchanges 3 messages. > That's why Diffie-Hellman is preferred.
Thanks for the link there - it seems they have most of the book there as 'sample' chapters :) The protocol bears much resemblance to the one I described, but using modular math/discrete logarithms to solve the problem. It even has a note at the bottom of that section - "While it might appear that any commutative cipher would suffice in place of modular exponentiation in protocol 12.22, caution is advised. For example, use of the Vernam cipher would be totally insecure here, as the XOR of the three exchanged messages would equal the key itself." It's only disadvantage is the requirement for very large numbers for the 'modular exponentiation' - something required in all pubkey ciphers (if you read the link in my other reply, that might explain why I'm trying to avoid that :) Nick Johnson _______________________________________________ freenet-tech mailing list [EMAIL PROTECTED] http://lists.freenetproject.org/mailman/listinfo/tech
