Color Image Encryption Research Based On Hyper-Chaotic System

With the dramatically development of Internet in information age,more and more people transmit information over the internet.At the same time,the security of information is paid much attention,digital image is the important information carrier,image encryption is the most direct and effective method to ensure the safety of the digital image information.We have proposed two hyper-chaos based color image cryptosystem;it is proved their security by simulation and performance analyses.The first scheme is based on hyper-chaotic system and hash function.In the cryptosystem,the initial values of chaos are updated by hash value,it improved the security of key.And the hyper-chaotic system can generate the random sequence which has higher randomness than that generated by normal chaotic system.In addition,before the scramble process,to reduce the correlation between the three components,R,G,B component of color image is inserted by each other.The pixel of current encrypted is effected by two pixels has encrypted in confusion,it enhances the plaintext sensitivity.The image encryption scheme has larger key space and stronger plaintext sensitivity showed by simulation results,it can resist brute force attack,statistical attack and differential attack.A high performance cryptosystem should have good robustness,a secure image encryption algorithm is proposed with linear feedback shift(LFS).In the confusion process,the plaintext matrix is converting into a binary array,and then cycle shifted,the process is efficient and has better effect.Utilizing the hash function to update the five initial value of 5D hyper-chaos also,the distance of linear feedback shift is decided by the processed sequences,then a exclusive or operation is carried out between the acquired matrix and key matrix.It is proved feasible by simulation,and the performance analysis shows that the cryptosystem has larger key space and can effectively resist noise attack and cropping attack.