Encryption Research Based On Dynamic Random Grouping And Chaotic Modulating FRFT Rotation Factor

In the explosioning information period,the information security seems more important.However,there are still some hidden dangers in the current encryption algorithm.In fractional Fourier transform(FRFT)image encryption method,the singleness of rotation factor and grouping will cause the security problem.As a result,a novel encryption method,namely chaotic dynamic random grouping and random modulating FRFT rotation factor is proposed.Three chaotic systems is adopted in this process.Firstly,the keys of system 1 are utilized to realize the nondestructive encryption on plain text and obtain the first cipher text.Then system 2 is utilized to realize the dynamic grouping of FRFT,and system 3 is utilized to realize random modulating the rotation factor of FRFT.Finally,the FRFT,which is dynamically grouped and the rotation factor is randomly modulated,is utilized to realize the second encryption on first cipher text.Compared with destructive method,in the first encryption,the real-time and reduction test shows that the decrypted time of nondestructive method decreases 52.5% and the similarity of decrypted image improves 4.5%.Meanwhile,denoising process can be avoided and the system overhead can be reduced.Security test shows that the decipher probability on exhaustive method reduces by 103635 times,compared with simple modulate FRFT rotation factor algorithm.The results show the proposed method is better than the chaotic key simple modulates FRFT rotation factor algorithm in real-time,reduction,security and so on.And it provides a novel way to protect the system structure.In fractional Fourier transform(FRFT)image encryption algorithm,according to the problem,one plain-text word is correlated with single cipher-text word,which can not efficiently resist chosen plaintext and chosen cipher-text attack.Based on chaotic dynamic grouping oriented FRFT,double-feedback image encryption method was proposed.Firstly,cipher-text feedback is applied to drive the two chaotic systems.And then the chaotic systems driven by cipher-text feedback are utilized to encrypt.The test results of feedback coefficient sensitivity shows that when ? is between 3.98 and 4,and the feedback coefficient is 0.1,the coefficient sensitivity is larger than or equal to 10-16,compared with other cases,the sensitivity of feedback coefficient is increased by at least 1013 times,so the security is improved significantly.Finally,the safety condition of system points out that the feedback coefficient is less than 0.4,which provides a new method for evaluating the safety of the feedback system.