The Research And Implemention Of General Secure Telephone For PSTN

PSTN Telephone has been a widespread and common utility in the world. It is a part of our social lives. However, because of the PSTN design faults the security problems have became more and more serious. Particularly, in those important departments such as governments and military departments, security problems are more severe. Wire tapping, imitating and denying have caused great losses of global users.Up to now, PSTN providers have invested a lot of costs in building and maintaining their bone networks and subscribers cycle circuit. It is impossible to transform PSTN into secure PSTN right now. Furthermore, the cost must be very high. So, enhancing the security of PSTN is a feasible solution.The security problems and solutions existed are analysised in this paper. And a new solution –– Secure Telephone System –– is proposed. Secure Telephone System provides integrate security services: confidentiality, authority certification, integrality and anti-denying. This system is applied in not only PSTN but also non-security system based on circuit switched networks.Specifically, the contributions of this paper are as follows:A new and integrate solution for general secure telephone for PSTN is proposed.A solution for voice encryption is proposed.The issue of applying PKI to PSTN secure telephone system is proposed and the current PKI is improved. At the same time, Light PKI and its supported tow parts including Small Group Principle and Active CRL Method are given.Authority Certification and Session Key Exchang Protocol is given. CRL updating problem is researched and the Active CRL Method and its protocol are given.The problem of CRL updating is solved by complexing channel.The design of terminal equipment of general secure telephone for PSTN is presented.Platforms for security telephone are researched and an experimental platform is choiced.A secure telephone terminal is designed and implemented based on PC and Linux Operation System.The terminal has been tested.Security Telephone System has a good chance of wide applying to governments, military forces, party branches and giant companies. Terminal equipment of security telephone has good commercial values. The main ideas and methods are applied to Chinese Government for patent, and the applying serial number is 03117842.1.