Abstract: As the current popular chaos-based image encryption algorithms with the permutation–diffusion structure have security flaws of no immunity to attack. A new image encryption algorithm was proposed based on the analysis of current algorithms, which can well resist the chosen-plaintext and the chosen-ciphertext attacks. The algorithm uses Kent chaotic map to generate key streams, and produces the parameters of the chaotic system and the iteration times according to the characteristics of plaintext pixels and input key. Firstly, the positions of pixels were shuffled totally with the chaotic se-quence. Secondly, the 0 and 1 bit positions of image pixels were scrambled by using another chaotic sequence generated by the input key. The experimental results show that the algorithm cannot only resist the chosen plaintext attack and chosen ciphertext attack but also achieve better cryptographic properties,such as key space, statistical analysis.