Research On Image Encryption Algorithm Based On Chaos Theory

With the rapid development of digital multimedia technology, the problem of information security becomes more and more serious. Digital image has become an important medium for multimedia communication because of its image, intuitive and vivid characteristics. In order to ensure the security of the digital image in the transmission process, the most direct and effective method is to encrypt the digital image. The digital image has the characteristics of large amount of data, high redundancy and high correlation, so the traditional encryption algorithm is no longer applicable. Chaos theory has been widely used in image encryption because of its randomness and sensitivity to initial values. In order to solve the problem of image encryption, the key space is small and the security is low, the chaotic system and hyper-chaotic system are applied to the image encryption algorithm. This paper mainly has done the following work:Firstly, the research development at home and abroad as well as significance of the chaotic image encryption algorithm are analyzed, introduces chaos theory,cryptography and chaotic cryptography and other relevant theoretical knowledge,and the relationship between the two is analyzed. Then the digital image encryption algorithm design principles, design steps and image encryption evaluation criteria are summarized.Secondly, an image encryption algorithm based on chaotic map is designed. The algorithm generates a control parameter in the scrambling stage using Logistic mapping, first image scrambling into global block scrambling using Arnold mapping,reached two times the scrambling effect, sequence generated by Henon chaotic map,after suitable treatment and XOR scrambling image pixel values to achieve change full, upset pixel correlation of the image, to achieve a good encryption effect. The experimental results show that the algorithm is simple and easy to operate, the key space is large, and it can resist all kinds of attacks effectively.Thirdly, this paper proposes a more chaotic image encryption algorithm based on improved Arnold transform, which realizes the encryption of image. First of all,the traditional Arnold transform equation is improved to improve the scrambling effect and scrambling performance, and the Kent mapping is introduced to generate the control parameters of the Arnold transform, so that the obtained Arnold matrix is different every time. Secondly, using two-dimensional Logistic mapping to replace the encryption operation with gray value. Experimental results show that the proposed algorithm has good scrambling degree and large key space, and can effectively resist various statistical attacks.Finally, aiming at the defects of the existing chaotic image encryption algorithm based on chaotic map,put forward many rounds of selection of adaptive image encryption algorithm, the algorithm first uses Logistic-sine chaotic map to the plain image position scrambling, and then the hashed image is divided into 2*2 sub blocks,and then use the sub block image hyper-chaotic system conducted several rounds of selection adaptive encryption, until all the sub block image encryption is completed.The experimental results show that the proposed algorithm improves the original encryption algorithm, which can effectively resist various attacks, and has good anti noise performance and good robustness.