Dynamic Key Encryption And Decryption Algorithm Based On Chaos Theory

With the rapid development of computer technology and the Internet, information security has become the focus of people's attention .It is of not only a great strategic significant issue in the process of information construction, but also a hot and difficult problem in today's world . Encryption is the core technology to the realization of the network and information security. At present, chaotic encryption ,which belongs to the endless variety of encryption algorithm , has a good prospect in the field of information security and show a vigorous development situation. Therefore, people attach great importance to the research of chaotic encryption.Chaos thinking goes back to ancient times, but it was used for encryption in the 1990s. chaotic sequence with the features of randomness , the extreme sensitivity to the initial conditions , ergodicity and aperiodic traversal sensitivity , show excellent cryptography performance. DES is a typical representative of block cipher in modern cryptography, which is widely used in government, financial and other important financial institutions. Although DES is deciphered through exhaustive attack because its small key space, people are still keen on improving its safety performance because of its deep social and business resources.Combining correlative theories such as chaos theory , neural network theory, DES encryption algorithm, Biology DNA Reform Technology and other relevant theoretical research ,this paper design two new dynamic key encryption algorithm. Through the chaotic map or a chaotic neural network produces chaotic sequence, which is reorganized as the DES algorithm dynamic key. After encrypting a block plaintext ,the key is transformed to achieve "one-time pad" encryption. Two algorithms combine perfectly sequence encryption and block encryption, showing high security. such as follows: (1)An Dynamic Key Encryption Algorithm Based on Logistic Map. The algorithm designs the same Logistic Map .The parameters and initial value of Logistic mapping is used key. Logistic mapping produces chaos sequence. In order to get better random sequence and taking into account the requirements of encryption speed ,the chaos sequence is use after 1000 iteration. The chaotic sequence is mapped to the 64 binary sequence, which encrypts a 64 plaintext block combining DES algorithm and DNA sequence migration recombinant algorithm . DES initial key is in the mode of dynamic change.(2) An Dynamic Key Encryption Algorithm Based on neural network. Chaotic neural network is a interconnection network linked by a number of neurons . Select Aihara chaotic neural network model output chaotic sequence. The link right value matrix W_ij and external input I are used the initial key. The Output chaotic sequence isreorganized by Biology DNA Reform Technology Algorithm and feedback to the chaotic neural network as new random seed to produce a new chaotic sequence. Therefore the chaotic sequence cycle tends to infinity. Similarly, After encrypting a 64 bits block plain text ,the key is transformed to achieve "one-time pad" encryption.(3) The algorithm is simulated through text encryption and images encryption in the computer. Made an analysis on algorithm security from the perspective of theory.