Kerberos is a network authentication protocol that was developed by MIT and now widely used by various organizations. Microsoft Corporation uses Kerberos as their network authentication protocol in their latest network operating systems family [Windows 2000 and Windows XP]. Key performance issues of authentication protocols have always been the compromises by cryptanalysis over the ciphers used. While speed of the authentication is most important in authentication protocols, a strong cipher also is most desired by the users. This thesis analyses the performance of the authentication protocol in question with various encryption algorithms. Apart from the stronger encryption and decryption achieved in the proposed variant, the speed of the authentication also greatly improves with this new encryption standard. When the key size for the encryption is increased and the authentication is within the known network, the performance is very much promis-ing with more transactions throughput. Standard key sizes and increased block sizes in the proposed encryption algorithm improves the cross network authentica-tion throughput largely.