Breaking an image encryption algorithm based on chaos

Recently, a chaos-based image encryption algorithm called MCKBA (Modified Chaotic-Key Based Algorithm) was proposed. This paper analyzes the security of MCKBA and finds that it can be broken with a differential attack, which requires only four chosen plain-images. Performance of the attack is verified by experimental results. In addition, some defects of MCKBA, including insensitivity with respect to changes of plain-image/secret key, are reported.Comment: 10 pages, 4 figure

Comments on "A Novel Compression and Encryption Scheme Using Variable Model Arithmetic Coding and Coupled Chaotic System"

Recently, Bose and Pathak proposed a joint compression-encryption scheme by incorporating an adaptive arithmetic coder with a coupled chaotic system [1]. In this comment, we first show that the scheme proposed by Bose and Pathak [1] is not decodable. It is due to the fact that the current symbol to be encoded is swapped with a randomly selected symbol in the model prior to encoding it, making it impossible for the decoder to mirror the encoder's operations. We then suggest a natural solution to solve the undecodability problem by using the last encoded symbol to swap. Unfortunately, it can be shown that this modified scheme is vulnerable against a chosen-plaintext attack