Cryptanalysis of an image encryption algorithm using Chebyshev generator

Recently, studies of image encryption algorithms have been increasingly based on chaos, but there still exist drawbacks in chaotic cryptosystem that threat the security. In this paper, we make cryptanalysis on an image encryption based on Chebyshev chaotic map and find the following: (1) chosen-plaintext attack can break the scheme. (2) There exist equivalent keys and weak keys for the encryption scheme. (3) The scheme has low sensitivity to the changes of plain image. And we successfully carry out the chosen-plaintext attack. To overcome the drawbacks, a remedial technique is suggested.