A novel blocked-based binary image authentication technique is proposed. The authentication signals of each 9×9 image block are placed in a selected 3×3 block within the 9×9 block. The authentication signal contains a certain relationship contributed by the standard deviation values of the other eight 3×3 blocks. Authentication signals are generated by rearranging the pixels in the selected 3×3 block. The rearrangement is designed according to a property of inverse halftoning to keep the visual change in the selected block imperceptible. By comparing the arrangement of the block pixels in a suspicious image with the extracted authentication signals, the fidelity and integrity of the image can be verified.