| Summary: | 碩士 === 國立暨南國際大學 === 資訊工程學系 === 98 === In recent years, due to the widely deployed network infrastructure, more and more services of the multimedia application are developed - one of the killer applications is Internet Telephony, which is also known as Voice over Internet Protocol (VoIP). Among many VoIP protocols, Session Initiation Protocol (SIP) is adopted by many companies to develop their products, because of its excellence in extension and ease of development. However the user authentication mechanism specified by SIP is still insecure to protect user identity. For example, users can not verify the legitimacy of the Registrar Server. Moreover, the user authentication key is stored in the database of the Registrar in plaintext form. Thus, the crime of identity theft occurs from time to time. Therefore, how to enhance the security of SIP authentication mechanism naturally gets more and more attention.
This thesis summarizes enhanced SIP authentication schemes proposed by many experts and scholars, and illustrates the security vulnerabilities and attacks to which those schemes may be subjected. Then, we propose an improved authentication scheme that is based on asymmetric key cryptography, which can prevent user identity from being impersonated even if the database of the Registrar is cracked and the user authentication key is stolen. Finally, implementation results show that the proposed scheme is efficient to be adopted in daily VoIP applications.
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