Research On VPN Tunnel Technology Based On GPRS/CDMA 1X Public Mobile Accss System

With the development of wireless communication technology, the authenticated users could use intelligent mobile phones,portable computers to conveniently access interior network of their companies anywhere at any time. To guarantee the security of information transfers, the information can be sent through the VPN(Vitual Private Network) tunnel. And the SDIO (Secure Digital I/O) Key can store cryptographic keys, providing digital signature and other security services. This kind of secure accessing system can be widely used in police, revenue searching, mobile application for companies, mobile electronic commerce and mobile banks. We do research on the VPN technology in the public mobile networks, mainly comprising the following aspects of work:At the beginning we study the PPTP, L2TP and IPSec protocols, and analyze the principle as well as the key technology of them. On the basis of these, we emphasize on the mechanisms of Encapsulating Security Payload (ESP) and some cryptographic algorithms. We also research on the Mobile VPN in CDMA 1x.Then we research on the structure of the VPN secure accessing system based on SDIO Key in the public mobile networks. Here VPN ensures the security of information with the help of SDIO Key. We also develop the encryption and decryption of short messages in GPRS, and test the encryption and decryption performance of short message with DES and 3DES algorithm, and the result of the testing turns out to be satisfying.In the last part we introduce the character and function of the SDIO Key. We research and design the structure of the SDIO Key and develop part of its software including the API functions and some application programs. We then test the auto detecting and certificate managing function of the SDIO Key, and the result of the testing meets the requirement.