Research On Dynamic AES Algorithm Based On Chaos Theory

At present,the main technology of the information security is encryption,but many of the current traditional encryption methods have more or less disadvantages.While chaos theory is a branch of nonlinear sciences,it has many advantages,especially the natural connection with the cryptography.Chaos theoryis very suitable for applying to the field of information security.And as the the advanced encryption standard?AES?,Rijndael algorithm has many advantages,such as simple design,high efficiency and the design of safety and principle.Therefore,taking the the common used files as an example,combining the chaos theory and the AES algorithm,a AESdynamic encryption scheme based on chaos theory was proposed in this paper.The main work of this paperis as follows.The Logistic mapping and Chebyshev mappingwere used as the chaotic system of the scheme in this paper.And they wereimprovedto increase the randomicity of key stream,to realize the effect of dynamic encryption.The specific improvementscheme are as follows.First,Logistic mapping and the Chebyshev mapping were combined to create the chaotic sequence stream.And the randomicity of sequence stream and the securityof the whole encryption scheme were improved.Second,the required key stream was broken up into parts.Some improved chaotic systems were used to produce the key stream by the way of iteration.It meaned that,except the first initial key was produced by the system randomly and needed to set,every initial key of the other iterative chaotic systems was the part of last ciphertext information.Third,because the initial key of the first group of chaotic system was set by own and there maybe existed some hidden danger.So the RSA algorithm was adopted by this paper,to ensure the security of the scheme.The Rijndael algorithmof 256bit and 256bitkeyplaintext was adopted by this paper as the main encryption algorithm.Every group of AES key was produced by the improved chaotic system.Then the plaintext block of the equal length as key block was taken as the input of AES algorithm together,to produce a group of ciphertext.Every group of ciphertext was produced by the same way.At last every group of produced ciphertext was merged to get the final ciphertext.The encryption scheme was tested from three aspects offunction,performance and security.The experimental results showed that the AESdynamic encryption scheme based on chaos theorycould effectively realizefunction of file encryption.The statistical data showed that the chaotic key stream used in the scheme had good randomicity.And the 256bit Rijndael algorithm's time complexity of brute force compution wasO(2²⁵⁶),which together ensured the securityof scheme.