The Research Of Digital Image Encryption Algorithm Based On Chaotic Theory

In recent years, with the rapid development of Internet communication technology, information security has become more and more important. Image, as a carrier of information, its encryption technique has already been useful and needs to be further developed.Chaotic dynamical system is a deterministic system in non-linear dynamics. There are lots of corresponding features between chaos and classical cryptography. When security of traditional cryptology is confronted with threats, some appealing characters of chaos, such as complexity, sensitivity to the initial conditions and control parameters, pseudo-randomness and unpredictable property, provide new directions for cryptography.First, the fundamental knowledge of chaos theory and cryptography is introduced, and the relationship between them is discussed. Second, several primary techniques of encryption based on chaotic system are introduced, and a comprehensive survey about previous research in designing chaotic cryptograph is conducted. Third, this paper reviews and analyzes the deficiencies of three important processes of image encryption, which are random sequence generator, scrambling algorithm and image encryption algorithm, and then redesigns the algorithm aim to overcome these shortage. Finally, adopt all kinds of performance standards to evaluate the randomness of binary sequence, the confusion degree of scrambling and the security of encryption algorithm, compared with the results of traditional algorithms.The research results in this paper indicate that the binary sequences produced by even-odd quantifying algorithm bear good balance, self-correlation and cross-correlation property. Compared with traditional algorithms, such as threshold quantifying and Middle Multi-bit quantifying algorithm, the new algorithm improves the security. The scrambling performance of the proposed double random scrambling algorithm not only has better scrambling effect, but also higher security. The redesigned image encryption system settles the contradiction between the diffusion and robust by hashing a parameter from the image as a component of the key.