The Research Of Chaos And Secure Communication

As a phenomenon found in non-liner dynamic system, chaos is deterministic and random-like. Based upon the sensitive dependence of chaotic systems on their initial conditions, a large number of non-periodic, continuous broadband frequency spectrum, noise-like, yet deterministic and reproducible signals can be generated, so chaotic technology is very useful for security communications. Based on chaotic technology, contemporary cryptology and their applications to modernistic information security and encryption, the author has performed comprehensive research and the research will be of great theoretical significance and applied value. The detail is clarified as follows:l)Based on the chaotic technology and contemporary encryption approach the paper put forward a new chaotic sequence, which introduced the m-sequence and the method of shrink key-the stream generator. The complexity of the sequence was promoted as the random alteration of the parameters of chaotic mapping, and at the same time, the shrinking key was used to enhance the security further more;2) The performance of one-way hash function was improved and new Hash Function construction methods are proposed through a novel hash method based on chaotic mapping and the AES-the Rijndael algorithm. The algorithm of hashing messages of arbitrary length into 256 bits hash values was designed. The algorithm have the good one-way property, high sensitivity to initial values and good security due to the intrinsic characteristic of chaotic system and Rijndael algorithm. The simulation experiment demonstrates the convenience and good hash performance;3) A new scheme of digital voice secure communication was proposed based on chaotic modulation without additional synchronization. The modulation sequence generated by chaotic logical mapping was used to encrypt the digital voice signal. In order to hide the character of information signal, the modulation was based on wavelet transform. The method of chaotic masking was also used torandomize the cryptograph. The computer experiments show that the chaotic encrypting system was fine in security and can resist the decipher analysis; what's more, the system is easy to realize.4) The paper discussed the application of the technology mentioned above in contemporary secure communication and a secure communication model of VoIP (Voice over IP) was investigated. The paper emphasizes on the discussion of the problems in implementation of network speech communication system of PC to PC in LAN and the schema of secure network speech communication. The AES algorithm, the chaotic sequence and the method of chaos modulation was adopted to encrypt the voice signal and the SRP protocol was used for identity authentication, so as to strengthen security. And some pivotal problems is discussed and settled, such as the compressing, restraining of reverberation and the obliteration of voice signal dither.