A novel public key self-embedding fragile watermarking technique for image authentication

Digital images are vulnerable to various malicious manipulations. So, effective techniques are demanded for assuring the integrity of image contents. In this paper, a public key self-embedding image authentication technique is proposed which can detect and localize alterations of the image contents and can restore the distorted regions. A doubly linked chain is used to embed block signature copies and two block codes into relatively distant blocks. Each block code can not only approximately rebuild a distorted block but also can, combined with another block code, rebuild the block with high quality. Moreover, the proposed technique uses a public key in the verification process that enables verification of the image authenticity without knowing the private key used in the embedding process. The experimental results show that the proposed technique is sensitive to pixel changes and provides secure embedding of the blockwise image signatures. Furthermore, it thwarts many attacks, specially the collage (also called vector quantization, blind copy, or pattern matching) attacks and can successively recover the image attacked areas.