Research And Design Of Encryption Algorithm Based On Chaotic Theory

Chaotic systems have a number of interesting properties such as random-like, sensitivity to initial condition and system parameters , ergodicity, mixing poroperties and so on. The close relationship between chaos and crytography makes chaotic encryption a natural candidate for secure and cryptography. Based on statistical analysis on chaotic system, a new chaotic map was proposed in this paper, and its properties was analyzed, the results show that the new chaotic map has better security than some existing chaotic map. After studing the cryptographical properties of some existing chaotic systems, an image encryption algorithm based on random key and "quasi-standard map" was analyzed, and the drawbacks of the algorithm were pointed out. On the one hand, the encryption algorithm using directed chaotic series can not resist the known-plaintext attack, on the other hand, the algorithm shuffling the position by two chaotic maps were provided with small secret key space.Then, a novel image encryption algorithm based on two chaotic sequences sort was proposed. By scrambling the positions of pixels and encryption the pixel values simultaneously, the performance of security is better than some exsiting algorithms. In order to enhance the security, another new chaotic agrithm for image encryption based on Liu chaotic system and general Arnold map was also proposed. By using the multidimensional Liu chaotic map instead of one-dimensional chaotic map, the security were enhanced. Simulation results and analyses show that the algorithms have the properties of random permutation , well randomicity and uniform distribution. Due to realizing in double-real precision, the algorithms are provided with big secret key space . The characteristic of plaintext were diffused in ciphertext. So the systems reduced the correlation of plain text and ciphertext. The proposed schemes have high-level security.