Abstract
Due to the rapid growth of technology, it is impossible to store all information in a single instance. This results in the development of distribution system. A distribution system means a set of interconnected nodes. Hence, how to guarantee the communication security between nodes is a major topic of modern network security. Currently, Kerberos is the most widely-used authentication scheme for distribution system. In Kerberos, user verification is achieved by a central authentication server. This server will give user an identity credential a after the verification. With this credential, user can access resources spreading in multi-nodes. Because adopting central authentication policy, Kerberos provides a convenient functionality—single sign on. But Kerberos has potential weaknesses which result from its password based architecture, purely symmetric cryptography, and the assumption that a client can securely protect users’ verification documents. Therefore, the objective of this thesis is to propose a secure network authentication system based on Kerberos, biometric verification, and public-key technology. Biometric verification can provide a stronger evidence of one’s identity than password verification. By adopting biometric verification, our system can avoid the risks result from using vulnerable passwords. Besides, in our system, user’s authentication documents do not exist in any client but in a portable device—smart card. This storage tactic leads to the result that the storage-security of user’s data is independent of client’s security. In our system, application server does not manage the log-in procedures of users directly, and a trusted log-in management server is responsible for this task. This brings two benefits. First, application server can concentrate itself to service providing. Second, we can prevent security loopholes result from diverse management policies. The log-in procedures managed by the log-in management server include biometric verification and later log-in checks. A user must be verified using his biometric features before presenting the ticket to application server. After these checks, the user can receive a session key to the application server. In order to prevent hackers from embezzling this key, log-in key can be used just once. Because symmetric cryptography is generally constructed of simple computing logic units, these algorithms can run fast. But in symmetric cryptography, the shared secret is necessary and this will lead to some security loopholes. On the other hand, because of the nature of asymmetric cryptography, user does not share a secret with his communicating parties. However, these algorithms suffer from poor performance. Hence, by adopting a mixed mode of both symmetric and asymmetric cryptographies, our system can achieve a trade-off between security and efficiency. In summary, our authentication system is more secure than other systems and can achieve acceptable performance. Therefore, our system is more suitable to modern network environments than other authentication systems.