Research On The Cryptanalysis Of A Class Of Image Chaotic Cipher Using Permutation-Diffusion Approach

Since 1989,chaotic cryptography has become an interdisciplinary subject combing chaos theory and cryptography,which has attracted close attention from researchers.Especially in the area of big data privacy protection and data security,chaotic cryptography as a new cryptosystem technology has fuitful research papers and broad application prospects.However,compared with classical cryptography,chaotic cryptography is still in its infancy and lacks security analysis measurement standards in chaotic cryptography,which lead to various security drawbacks exist in many chaotic cryptosystem and deciphered.It also restricts the chaotic cryptography technology further development and reaches the maturity of practical application.Hence,this thesis cryptanalyzed five image encryption algorithms based on chaotic systems and other special mechanisms.The main works are given as follows:1.In 2019,an image encryption algorithm based on compound chaotic sequence was proposed,the algorithm adopted three-level encryption structure of permutation-forward diffusion-reverse diffusion.From the respective of cryptanalysis,three-level encryption structure of permutation-forward diffusion-reverse diffusion was simplified to two-level encryption structure of permutation and diffusion.Moreover,the chaotic sequences generated by the encryption algorithm were irrelevant to the plaintext images or ciphertext images,hence,the corresponding equivalent keys were broken through utilizing chosen-plaintext attack.2.In 2019,a color image encryption algorithm based on Hopfield chaotic neural network was given.The original chaotic image encryption algorithm included permutation encryption and diffusion encryption.The result of cryptanalysis pointed out that the chaotic sequences generated by this algorithm were independent of plaintext image,and there exist equivalent permutation key and equivalent diffusion key.Therefore,the equivalent diffusion key and the equivalent permutation key could be obtained by using chosen-plaintext attack,and the plaintext image was further recovered from the ciphertext image.3.In 2018,the security analysis of a bit-level image chaotic encryption algorithm based on the 1D chaotic map was proposed.The original image chaotic encryption algorithm included bit-level permutation encryption,diffusion encryption,and linear transform.From the respective of cryptanalysis,bit-level permutation encryption,diffusion encryption,and linear transform could be simplified into bit-level equivalent permutation encryption and equivalent diffusion encryption,which is a key breakthrough point of cryptanalysis.Moreover,the chaotic sequence generated by this algorithm is independent of the plaintext image.Therefore,the equivalent diffusion key and the equivalent permutation key were obtained by chosen-plaintext attack,respectively.4.In 2019,an image encryption algorithm based on 2D Sine-Tent chaotic map was proposed,which adopted two-round permutation and two-round diffusion structure.From the perspective of cryptanalysis,it was found that two-round permutation could be equivalent as a single round one.It was the key point that under differential cryptanalysis attack,two-round diffusion can be eliminated by selecting only one pure plain-image and its corresponding cipher-image.That is,the diffusion key was invalid for the cryptosystem.The equivalent permutation keys could be revealed by using chosen-plaintext attack.5.In 2019,an image encryption algorithm based on double permutation and C-R chaotic system was proposed,which adopted mutiple-round encryption structure and each round included row permutation-column permutation-global permutation-diffusion.From the perspective of cryptanalysis,it was found that mutiple-round encryption could be equivalent as a single round one,moreover,row permutation-column permutation-global permutation was equivalent to a total permutation in each round.It was the key point that the original encryption algorithm was equivalent as single round permutation and diffusion encryption structure.Therefore,the equivalent permutation keys could be revealed by using chosen-plaintext attack.