Real-time Voice Communications Technology Research, Based On The Gsm Csd Channel Encryption

With the rapid development of mobile communication technology, the mobile phone not only plays an important role in personal communication, but also is widely used in official and commercial activities. But, because of the use of interception technology, the voice in personal mobile communication may be intercepted by others when callers are communicating, that forms huge security threats to callers. Therefore, achieving secure communication is user's natural requirement, especially, in all aspects of national security and social economic life, how to insure secure voice communication is very important.GSM (Global System for Mobile Communication) has been widely used by people as the central mobile communication system. However, secure design of GSM network is mainly for wireless channel, and the main secure criterion is designed for operator. These measures are mainly used to prevent fraud and network misuse. There are serious secure risks in communication contents when mobile communication users are communicating, which are unable to meet the requirements of voice secure communication.To this problem, in the research, CELP(Code-Excited Linear Prediction) technology is used to coding the voice, CSD(Circuit Switch Data) of GSM is selected to be the data channel. Complete technology about voice stream encryption and decryption is designed. In addition, by dealing with share secure key further after secure key-exchange, the safety level is improved. The main contents in the thesis include the following aspects:1. GSM mobile communication technology and it's security situation were analyzed.2. Voice coding technologies were researched Systematically.3. Secure key-exchange and data encryption techniques concerned in the investigation were researched, and an effective method about voice data encryption and decryption is designed.4. Real-time communication system of encrypted voice based on CSD channel of GSM was designed and achieved.In this thesis, the study on the real-time communication system of encrypted voice based on CSD channel of GSM is completed. By analyzing the security of GSM system, due to the bandwidth of CSD channel is limited, and mobile phone's operation capability is not enough strong, voice coding technique was researched, voice data encryption technique is proposed. Using embedded programming and cross compiler technology, real-time communication system of encrypted voice based on CSD channel of GSM is designed and achieved.The achievement about real-time communication system of encrypted voice based on CSD channel of GSM make the problem of voice communication insecurity be solved. That increased security of personal mobile communication, prevented voice contents be intercepted by others in voice communication, protected caller's privacy, there are very good application value in government affairs, business activities and other important occasions. Moreover, the technology about voice data stream encrypt and decrypt mentioned in the thesis has very useful referenced value for other stream data encryption.