The Use of Belief Logics in the Presence of Causal Consistency Attacks

This paper discusses a class of attacks against cryptographic protocols that have not been previously representable using BAN-style logics. This problem has resulted in the generation of proofs of these protocols that validate nal beliefs of the protocol participants even when successful attacks against these protocols have been demonstrated. The failings of the BAN-style proofs of these protocols does not arise from failings of the logics, as alluded to by others, but rather in the use of the logics. This paper looks at the Needham Schroeder public key protocol which has recently been demonstrated awed, the analysis of the protocol, where the use of the logic failed in the proofs of this protocol and suggests a speci c approach for using the logics that avoids these problems.