Re: timestamp based protocol

On Tue, 31 Jan 2006 16:55:27 +0100, "cicap" <cicap@xxxxxxxxxx> wrote:

>In a session-key distribution protocol, Bob should check that:
>1) "tB - tA" is in the acceptance window range.
>2) tA is different from all other received timestamps.
>I don't understand point 2!
>What could do an enemy without point 2??
>(I ask that because I am a student and my book is not very clear at this

Possibly they are using the timestamp tA in the generation of a nonce
or IV, although this seems ill-advised.

Or they are trying to avoid some type of replay attack.