The Novel Image Encryption Scheme Based On Three-Dimentional Chaotic System

With the development of network technology,a large amount of information has been generated,transmitted and stored.As an intuitive form of information expression,image plays an important role in information transmission.The increasing number of cybercrimes has brought serious impacts on information security,and the importance of image security is getting more and more attention.It is urgent to propose new and secure encryption algorithms to meet the challenge.As the image contains a large amount of data,has high redundancy and strong correlation between pixels,the traditional encryption method for text and other information is no longer applicable.The chao has excellent characteristics such as initial value sensitivity,pseudorandomness,and long-term unpredictability.All those make it has great advantages to image encryption.Some existing chaotic image encryption algorithms have irreconcilable contradictions in terms of security and implementation complexity.Low-dimensional chaotic systems have low complexity but poor performance in the against of robust attacks.Space-time chaotic systems or ultra-high-dimensional chaotic systems have higher complexity and security but more implementation costs.According to the problems above,this paper meanly studies the image encryption scheme based on three-dimensional chaotic system.According to the inherent properties of gray image and color image,the gray image encryption scheme based on Lorenz chaotic system and the color image encryption scheme based on Chen chaotic system and Logistic chaotic map are proposed respectively.The former applies a three-dimensional Lorenz chaotic system to the encryption of the gray image,and uses a pseudo-random number generator to transform the sequence generated by the Lorenz system to ensure better randomness.Then the random sequence is used for the diffusion and permutation parts of the gray image encryption,respectively.It aims at changing the position of the image pixel and the value of the pixel.The latter uses the three-dimensional Chen system and the onedimensional Logistic system to encrypt the color image.Firstly,the sequence generated by the Chen chaotic system is stretched and folded,so that the it can have good randomness.And it will be used in the diffusion phase of the red,green,and blue portions to change the position of the pixel.Then the same method is used to stretch and fold the sequence generated by the Logistic system to change the pixel values of the red,green and blue parts.The innovations of this paper are mainly reflected in the two aspects: First,two new types of pseudo-random number generators are designed,and the randomness is further improved by stretching and folding the output sequence of the chaotic system.The designed pseudo-random number generator is skillfully applied to the permutation and diffusion part of image encryption,it can greatly improve the security of the overall encryption scheme.Secondly,a new image random permutation method based on chaotic pseudo-random sequence is proposed.According to the chaotic key stream,the algorithm randomly selects row or column to permutate.And the multiple rounds of permutation further ensures the security of the operation.The experimental results show that the above method is effective for both gray and color images,so it has good universality.The chaotic image encryption scheme proposed in this paper is not only easy to implement,but also can resist common attacks.Compared with the other existing chaotic image encryption scheme,it also shows good superiority.