Performance of Public-Key-Enabled Kerberos Authentication in Large Networks

Several proposals have been made to public-keyenable various stages of the secret-key-based Kerberos network authentication protocol. The computational requirements of public key cryptography are much higher than those of secret key cryptography, and the substitution of public key encryption algorithms for secret key algorithms impacts performance. This paper uses closed, class-switching queuing models to demonstrate the quantitative performance differences between PKCROSS and PKTAPP—two proposals for public-key-enabling Kerberos. Our analysis shows that, while PKTAPP is more efficient for authenticating to a single server, PKCROSS outperforms the simpler protocol if there are two or more remote servers per remote realm. This heuristic can be used to guide a high-level protocol that combines both methods of authentication to improve performance.