A N-party Diffie-Hellman Key Exchange Protocol Based on Verifier

In this paper we show that the password-based Diffie-Hellman N-party EKE-U key exchange protocol due to Byun and Lee suffer from server compromise attack. And we present a secure n-party PAKE protocol based on verifier in the unicast network. In this protocol, the verifier is computing from the password of a client. The server stores and uses the verifier to authenticate the client. The security analysis shows that the proposed protocol can resist many familiar attacks including dictionary attacks and password guessing attacks.