At 12:22 AM 5/19/04 +0100, Peter Fairbrother wrote:

Peter Fairbrother (Who is right now composing a talk about the uses of modexp in crypto,

for

those far more knowledgeable than I)

Modexp is Prometheus send from Olympia to let us speak between ourselves. Modexp has many implementation subtleties. Modexp performs what, in a block cipher, would be called mixing, by using multiplication. (e.g., The IDEA block cipher uses multiplication for this.) Modexp is stirring dye into water by turning the cranks of an eggbeater a certain number of times, and then getting the dye back to its original position by reversing the motion a different, but related, number of times. DH is ephemeral, where "identity" is merely a communication endpoint constant for the session. RSA lets you release (not necessarily publish in the phone book sense) *persistant* authenticators for persistant "identities". So you can assure that an endpoint is the "same" across sessions across time. Modexp is the core of it all. "All is number" -Pythagoras