Date: Tue, 26 Jul 1994 00:11:34 -0700 From: norm@netcom.com (Norman Hardy) At 14:43 1994/07/25 -0700, Sandy Sandfort wrote:
The questions are: Could standard auto and garage door openers easily be retrofitted? Could a "crypto remote" with its own CPU be made small enough to fit into a hand-held unit? Could such a system be made for a reasonable cost?
Sounds like an application for a "challenge-response" system. But that would require transmission from garage unit to car unit. If there were syncnronized clocks then the signal could be a function of time so that the above replay would fail. That requires only a PRNG. Why not generate a random number, checksum it, and sign it using a public key? Or is that overkill? -russ <nelson@crynwr.com> http://www.crynwr.com/crynwr/nelson.html Crynwr Software | Crynwr Software sells packet driver support | ask4 PGP key 11 Grant St. | +1 315 268 1925 (9201 FAX) | What is thee doing about it? Potsdam, NY 13676 | LPF member - ask me about the harm software patents do.