Block-Chain Based Fragile Watermarking Scheme with Superior Localization

This paper proposes a block-chain based fragile watermarking scheme to address the issue of security and accuracy of tamper localization. The relationship between the security strength and block size is also discussed. In the proposed scheme, all blocks in the original image randomly form a linear chain based on the secret key in such a manner that the watermark of an image block is hidden in the next block in the block-chain. In the tamper detection process, the legitimacy of image block is determined by the adjacent blocks of the block and the following block in the block-chain. Compared with conventional block-wise fragile watermarking techniques, the proposed block-chain based scheme not only satisfactorily resists the VQ and collage attacks, but also improves the localization accuracy without sacrificing security. Moreover, the security strength is proposed to quantitatively evaluate the security ability of fragile watermarking techniques.