Attack to an image encryption algorithm based on improved chaotic cat maps

A security of an image encryption scheme based on improved chaotic cat maps was analyzed. In these analyses, it has revealed some rules of key information leaking in certain instances, and has pointed out that the algorithm is insensitive to both the control parameters and the changes of plaintext. In the condition of known-image attack, an equivalent key-solved algorithm about once iteration and more iteration are proposed respectively. Simulation experiments show that the equivalent decryption image can be obtained by using the above key-solved algorithms, and therefore the original algorithm is insecure in the known image attack.