It is not dependent on time. You'd like a protocol to be self sufficient if at all possible. Moving the vulnerability of one protocol to another is not highly desirable in general. Looking forward to reading your research results when available. Regards Bora On 9/18/07 9:25 AM, "Xin Liu" <smilerliu@xxxxxxxxx> wrote: > Sequence number has its own problems. Message sources have to remember > sequence numbers even when it reboots or crashes. Message verifiers > have to keep states too, and whenever the states go wrong due to > attack or random errors, it's hard to detect and fix them. > > Best > Regards, > > Xin Liu > > On 9/18/07, Bora Akyol <bora.akyol@xxxxxxxxxx> wrote: >> You can check freshness of a message by means of sequence numbers, no? >> >> Bora