Speech Chaotic Encryption Algorithm Research And Its Application In Speech Secure Communication

Speech sounds is an important means for human communication and exchange. With the constant development of science and technology, the distant voice communication is possible, which become the most commonly used and the quick approach for people to communicate and convey information over long distances. Along with the computer network technology and modern voice digital processing technology advances, people try to use computer network for speech communication due to the equipments of computer network are simple and the digital voice communication is at a lower price. Thus, it will soon become an important way of speech communication. However, the computer network channel is relatively exposed, which can be a tremendous threat to the safety of voice communication network. Whereas, the speech or other multimedia data will be with a great quantity of data, and the voice communication demand high instantaneity, so it is inappropriate to apply the traditional way of password encryption algorithm to the speech communication secrecy.This thesis focuses on the chaotic encryption. Firstly, it introduces the development and the trend of the speech encryption, discussing the relation between the Cryptography and the Chaology, on top of which, it studies the related theory of the Chaology and chaotic password’s design thinking; Secondly, it introduces a chaotic encryption algorithm with scrambling-spread structure, analyzes the safety defects of the original algorithm and proposes the corresponding algorithm. The improved algorithm, which makes use of the cat mapping and logistic mapping to complete the scrambling and diffusion process, realizes the chaotic encryption. Thirdly, it makes the performance analysis of the improved chaotic encryption algorithm, which is turned out to be a good algorithm, and it can effectively ensure the safety of the encryption content. At the same time, the algorithm encryption is fast and very suitable for speech sounds and other multimedia data encryptionIn addition, this thesis also introduces the design and the realization process of a voice communication security system based on the improved algorithm in detail. The system employs the VC++6.0for development and uses multithreading technology, voice compression technology and improved chaotic encryption algorithm, which realizes user login and online user authentication, the display of on-line users, key negotiation, request calling and response, collection sending and speech broadcasting, speech data compression coding and decoding, speech data encryption and decryption, information controlling and voice data network transmission, etc. The testing results show that the system can run well to do all the functions above, and which can also realize real-time speech in security communication.