Abstract: In traditional identity authentication, only static passwords were employed. Besides, only one authentication server was utilized for offering service to customers. There are two disadvantages in the above scheme: static password can be easily broken; if the authentication server was breached or broken down, it wouldn′t offer the usual service to customers in time, and even result the loss of customers′ information forever. Hence, it is necessary to find a more effective identify authentication scheme. By combining dynamic password with intrusiontolerant technique, this paper presents a new identity authentication scheme that can effectively cope with the problems caused by both the breach of password and broken down of some authentication servers.