Study On Several Problems In The Mobile Communication Systems

With the continuous development of mobile communication technology, the application fields of mobile communications are also extending rapidly from traditional voice service to data and multimedia services and will further merge with the Internet. Due to diversification of services, security problems are also becoming prominent. This paper explores the security problems of mobile communication systems such as security problems in 3G mobile communication systems, security problems in IPv4, and security problems in mobile IPv6. The main research results are as following:1. Based on detailed analysis of the security system of 3G mobile communications, the author made improvements to the protocol of authentication and key agreement of 3G proposed by 3GPP so that the security of data transmission among service networks is strengthened.2. By introducing public key cryptosystem to the authentication mechanism, the author proposed a 3G authentications and key agreement protocol based on public key cryptosystem.3. Based on analysis of the main security problems of mobile IPv4 and aimed at authentication of the registration process, the author proposed a security mobile node registration protocol so that authentication between communication entities in registration processes is realized, freshness of transmitted message is insured, and imposter attacks and repeated attacks are prevented.4. Targeting on the requirement of AAA ( Authentication, Authorization, Accounting)of mobile environment, the author proposed a mobile IP registration scheme for integrated AAA and thus realized security transmission of mobile node account information.5.By analyzing security requirements of route optimization mechanism to banded updates authentication and introducing ID-based cryptosystem, the author designed an authentication scheme for banding updates based on route encryption. The scheme makes the transmit address as the public key and hometown agent HA as the key generation center so that reliance on PKI is avoided.6. Through exploration of cryptographically generated addressed(CGA) technique and analysis of CAM protocol, the author proposed an improved CMA protocol which can strengthen the authentication between communication entities.