Abstract: Based on Kerberos protocol,a novel authentication system is presented using Yaksha security system,which overcomes several limitations of Kerberos.In this system the public key cryptosystem is used to authenticate and exchange session keys mutually.In addition,timestamps produced by the user,instead of nonces,are employed to solve the problem of time synchronization,and password scheme is replaced by initialization protocol.High security and speed can be obtained,guessing password attack and replay attack can be prevented effectively ,and the problem of key management and storage is simplified.