On Sun, 8 Sep 1996, Lance Cottrell wrote:
Mixmaster prevents replay, so flooding multiple copies of a single message will not work. This is the reason Mixmaster has no reply block feature. I can see two ways in which replies can work safely.
To paraphrase John Von Neumann, any system which uses reply blocks is in a state of sin. By this I mean that if there is a chain pointing at you, a sufficiently powerful attacker can walk down that chain and find you. Given that, I will join the state of sin by proposing a mechanism which will allow Alice to receive a reply from Bob, but change her mind at any time. The basic idea is to have a one-time reply block which either Bob or Alice can send to. If Alice thinks that too much time has elapsed, and powerful enemies are walking down her reply block chain, she can send herself a reply and break the chain. (She might send a reply thru each link in the chain to break all the links.) It also occurs to me that since email addresses are about the same size as secure symmetric keys, it would be attractive to use real one time pads instead of symmetric key cyphers for encrypting them. ------------------------------------------------------------------------- Bill Frantz | "Lone Star" - My personal | Periwinkle -- Consulting (408)356-8506 | choice for best movie of | 16345 Englewood Ave. frantz@netcom.com | 1996 | Los Gatos, CA 95032, USA