Abstract: A restorable image authentication with cellular automata transform is proposed. The original image is splited into non-overlppin blocks and two layer cellular automata transform (CAT) is performed on each block. Authentication watermark and restoration watermark are produced from the second-layer low frequency coefficients and embedded into the first-layer low frequency coefficients of the current block and the corresponding block separately. Image authentication is played with the authentication watermark, and the tampered blocks can be restored with restoration watermark. Experiment results show that the scheme's security is strong and can resist vector quantization attack effectively.