A Public Key Watermarking Scheme for Image Authentication

Conventional digital signature schemes for image authentication encode the signature in a file separate from the original image, thus require extra bandwidth to transmit it. Watermarking techniques embed some information in the host image. In this paper, a public key based digital signature scheme for image authentication is proposed. The scheme extracts feature value from the pixels of the of the original image. This feature is used to compute the signature which is embedded into the DCT of the image as watermark, avoiding additional signature file. It is inspired by Wong’s Public Key Watermarking scheme which was later enhanced by Baretto. The watermarked image demonstrated high perceptual quality and robustness. It also proved to be robust against many common image processing operations and JPEG compression. The scheme not only can verify the authenticity and the integrity of images, but also can locate the illegal modifications. Keywordsblock based, digital signature, feature extraction, hash functio, jpeg, DCT