Security in Computing 5th Edition by Shari Lawrence Pfleeger, Charles P Pfleeger, Jonathan Margulies

Exercise 1

In this chapter we have described sequence numbers between a sender and receiver as a way to protect a communication stream against substitution and replay attacks. Describe a situation in which an attacker can substitute or replay in spite of sequence numbers. For which type of sequence numbering—one general stream of sequence numbers or a separate stream for each pair of communicators—is this attack effective?