Research On Improved Chaos Image Encryption Algorithm

With the rapid development of technology in the 21 st century,the communication between people has also changed,from the communication of envelopes to the communication of network media.At present,the network is widely open,and everyone can communicate through the network.At the same time,criminals will also threaten some information through the network.There are a lot of images in the network,so the security of images deserves attention.The information contained in the image involves many aspects,such as personal privacy,unit privacy,national privacy,etc.,and image encryption technology can effectively protect the corresponding information.In the development of image encryption technology,because chaotic map has the characteristics of sensitivity to initial value,pseudo-randomness and ergodicity,chaotic map can be well used in combination with image.The combination of chaos and images has attracted more attention from researchers.Compared with traditional algorithms,the combined encryption algorithm has better effects in terms of security,complexity and efficiency.This also makes chaotic cryptography rise in recent years,allowing more Many scholars are involved.However,the existing chaotic encryption algorithms also have insufficient chaotic characteristics and low-dimensional chaos is easy to break.In order to effectively improve the performance of chaotic encryption,this paper considers increasing the key space,enhancing the encryption effect,and increasing randomness and security.Two image encryption algorithms based on chaotic map are designed respectively.(1)An image encryption algorithm based on improved Kent chaos and hash function is proposed.The scheme prevents plaintext attacks,expands the key space,and strengthens the randomness of the system.First,the plaintext and the key are closely combined through SHA256 and SHA512,and the encryption effect of one-time pad is obtained;then block scrambling is performed;finally,the final ciphertext image is obtained by scrambling and diffusing traditional Logistic and improved Kent.The simulation results show that the scheme has a key space far exceeding the security requirements,strong key sensitivity,and good security and robustness.(2)A new Lorenz image encryption algorithm is proposed.The algorithm mainly strengthens the randomness of the chaotic system,solves the certainty of the control parameters,and further expands the key space.First,the key is generated by mixing the hash function with the original image,then the plaintext is scrambled by DCT transform and Joseph transform respectively,and finally the key is used to scramble and diffuse the sequence generated by the improved Lorenz system to generate the final ciphertext image.The simulation results show that the new Lorenz has a large enough key space,high information entropy and good statistical and differential analysis.