Cryptanalysis of Two Chaotic Image Encryption Schemes Based on Permutation and XOR Operations

Recently, two chaotic image encryption schemes were presented, in which shuffling the positions and changing the grey values of image pixels were combined to confuse the relationship between the cipher-image and the plain-image. In this paper, we provide the known/chosen plaintext attack to recover the corresponding plaintext of a given ciphertext. Furthermore, we point out that the two schemes are not sufficiently sensitive to small changes of the plaintext. Based on the given analysis, some means are proposed to strengthen the overall performance.