ABSTRACT A new image encryption algorithm based on convolution operation is presented in this paper. By using an external key of length 300 bits, several pseudo-random sequences are generated by Chen's chaotic system and general convolution operation, and then their statistical properties are verified. The proposed image encryption scheme includes one module of covering operation, two modules of diffusion operations, and one module of confusion operation. The covering module employs the pseudo-random sequence to cover the original plain image with binary XOR operation. The diffusion modules are based on the multiplication of finite field GF(28) and windowed convolution with summation of modulus 256, and dissemination of the information of any pixel in the original image to all the pixels in the diffused image. The confusion module uses each value of pseudo-random sequence as the offset address of pixel replacement to permute the diffused image. The simulation experiment and comparative analysis show that the proposed image cryptosystem has the advantages of fast processing speed, strong sensitivity, and high encryption intensity, and can be used as a candidate for practical image cryptosystem.