Yahalom is an authentication and secure key-sharing protocol designed for use on an insecure network such as the Internet. Yahalom uses a trusted arbitrator to distribute a shared key between two people. This protocol can be considered as an improved version of Wide Mouth Frog protocol (with additional protection against man-in-the-middle attack), but less secure than the Needham–Schroeder protocol.
Protocol description If Alice (A) initiates the communication to Bob (B) with S is a server trusted by both parties, the protocol can be specified as follows using security protocol notation: A and B are identities of Alice and Bob respectively is a symmetric key known only to A and S is a symmetric key known only to B and S and are nonces generated by A and B respectively is a symmetric, generated key, which will be the session key of the session between A and B
Alice sends a message to Bob requesting communication.
Bob sends a message to the Server encrypted under .
The Server sends to Alice a message containing the generated session key and a message to be forwarded to Bob.
Alice forwards the message to Bob and verifies has not changed. Bob will verify has not changed when he receives the message.
BAN-Yahalom Burrows, Abadi and Needham proposed a variant of this protocol in their 1989 paper as follows:Paul Syverson. A taxonomy of replay attacks . In Proceedings of the 7th IEEE Computer Security Foundations Workshop, pages 131–136. IEEE Computer Society Press, 1994.
In 1994, Paul Syverson demonstrated two attacks on this protocol.
See also Kerberos protocol Otway–Rees protocol Neuman–Stubblebine protocol
References
M. Burrows, M. Abadi, R. Needham A Logic of Authentication , Research Report 39, Digital Equipment Corp. Systems Research Center, Feb. 1989 M. Burrows, M. Abadi, R. Needham A Logic of Authentication. ACM Transactions on Computer Systems, v. 8, n. 1, Feb. 1990, pp. 18—36