A Encryption And Decryption Method Based On Stochastic Sequence Key

As science and technology develops, data encryption techniques show more important, and kinds of new encryption techniques and algorithms come forth. Stream cipher is an important private key cipher system. The stream cipher algorithms that had brought forward until now make use of Exclusive OR of key stream and plaintext in substance. Therefore the key of stream cipher system is creating of key stream, and the security of system is absolutely determined by the quality of key stream. "One-time pad" is the rudiment of stream cipher system. The key of "one-time pad" is a stochastic and unrepeatable character sequence. So in order to make the encryption have the characteristics of "one-time pad", it is necessary to structure the complexity of the algorithm that creates stochastic key sequence to improve the periodicity of key sequence.Combining correlative theories such as Neutral Network, Chaos theory, Genetic Algorithm, Biology DNA Reform Technology, it studies one encryption and decryption model based on stochastic sequence key. It has finished works as follows:1. It puts forward to one universal encryption and decryption model based on stochastic sequence key. Making ciphertext through the output that the function of key generator creates is Exclusive OR with plaintext, then making new stochastic seed over again through stochastic seed generator transforms key sequence that is the output of key generator, and transforming part of ciphertext through FFT, the model may form one highly safe encryption mode.2. On the basis of universal model, it studies the application realization of key generator. In the course of design, fixing stochastic seed generator as one model, it only discusses aiming at the change of key generator.3. On the basis of universal model, it studies the application realization of stochastic seed generator. In the course of design, it only discusses aiming at stochastic seed generator.4. It analyses the security of every model in the aspects of the sensibility that ciphertext contraposes the key and the ability that the model stands against attack.Getting across absorbing the characteristics of the colony's nonperiodic diversity that some algorithms gain, and Fast Fourier Transform's high nonlinearity, it puts forward to one universal encryption and decryption model. Through operating key sequence, the model improves the non-linear relationship between the key and the first stochastic seed, and doing the transformation of part of ciphertext, it avoids the ciphertext-only attack efficiently. The whole model enhances the periodicity of key sequence and the complexity of algorithm. Because of realizing the genuine "one-time pad", it can ensure the encryption system has the very high security.