----- Original Message ----- From: "Travis H." <[EMAIL PROTECTED]>
Subject: SecurID and garage door openers

Similarly, how do those garage door openers with "rolling codes" work,
given that the user may have pressed the button many times
accidentally while out of range of the receiver?

My understanding is that since it is a purely monotonic counter it is plenty possible to do one of two things: send {counter, data} instead of {data}, receiver stores last counter to avoid replays
have the receiver just keep counting forward for a while (not a good idea

Is there any interest in reviewing the security of consumer-level
devices?

I'd be willing to take a look at the protocol, but dissection is not my specialty.

PS: How many cypherpunks does it take to open a garage door?
http://www.cap-lore.com/Garage/

Currently, not very many, with proper designs openly published, not very many because not very many companies will use it. However, it could be a useful way for some cipherpunks to make some extra money. Anyone else up for it? and how about the car alarm? Joe


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