Authentication v Sample Clauses

Authentication v s. Identi cation Entity authentication is a process by which a participant is convinced of the identity of another participant. Entity authentication can be unilateral (one-way) or mutual (two- way). In a mutual authentication protocol, both participants wish to be convinced that the other participant is indeed who he/she claims to be. A concept that is closely related to and often confused with entity authentication is identi cation. While the aim of identi cation is similar to entity authentication, namely for one participant, say Xxxxx, to convince another participant, say Bob, of her identity, identi cation satis es a more stringent requirement: no participant other than Xxxxx can prove that he or she is Xxxxx, even to him or herself. The di erence between entity authen- tication and identi cation is made clear by examining a protocol based on a shared static key between Xxxxx and Xxx. Xxxxx and Xxx can mutually authenticate each other using the static key in three moves [30]. However, such a protocol is not an identi cation protocol, since whatever produced by Xxxxx using the shared key can also be created by Bob, and vice versa. An implicit requirement of key establishment in practical applications is that it o ers at least unilateral entity authentication or identi cation. A protocol that o ers both key establishment and (unilateral/mutual) entity authentication or identi cation is called a (unilaterally/mutually) authenticated key establishment. In secret key cryptosystem based protocols, entity authentication is almost exclusively achieved by way of challenge-and-response. A key establishment protocol employing public key cryptosystems can o er identi cation by the use of digital signature. Technically, some entity authentication or identi cation protocols may be xxxx xx to carry session keys, and conversely, an authenticated key establishment can also be used for the purpose of entity authentication or identi cation. Finally there is another concept related to authentication. That is key con rmation whose purpose is for a participant to acknowledge that he or she is indeed in possession of a session key. The last message of a key establishment protocol can be optionally composed of an authentication tag. The tag may be generated from a newly agreed session key by tag = M XXxxx(known message), where M AC may be instantiated with either a message authentication code or a keyed hash function.