Abstract: Image encryption is very important under the background of information security. The traditional encryption method uses integer-order chaotic sequence or one or more coefficients of other low-dimensional discrete sequence as the key to encrypt the image information. Because the encryption sequence is relatively simple and the key space is small, the security is not good. In this paper, an image encryption algorithm based on fractional Rossler chaotic sequence is proposed, which takes the order and system parameters of fractional Rossler chaotic system as the key to increase the key space, while the memory characteristic of fractional chaotic system effectively increases the complexity of chaotic sequence and makes it more secure in image encryption.

Key words: integer-order chaos, fractional chaos, memory characteristics