A Fast Image Encryption Scheme Based on Public Image and Chaos

A novel image cryptosystem based on public image and chaotic systems is proposed in this paper. In proposed system, with the help of piecewise linear map and Chen's chaotic system, a public key is used to generate a public image, and a secret key is used to generate three key streams for image encryption. Then, the public image and one key stream are used for covering image. The other two key streams are used for image diffusion. The image encryption system includes two covering modules, two plaintext-unrelated diffusion modules and one plaintext-related confusion module. With the use of public image and plain image related confusion operation, the proposed system can resist the chosen/known plaintext attacks. Each encryption process uses a new public key, then the public key and cipher image are transmitted to the receiver through the public information channel. Even for the same plain image, each encryption process will produce totally different cipher images. When the public key is authenticated, the image cryptosystem can prevent active attacks. The simulation results show that the proposed scheme possesses the merits of fast encryption/decryption speed and high information security, and can be used to protect the image information on the internet.