Image integrity and authenticity verification via content-based watermarks and a public key cryptosystem

A technique using the inherent feature map of an underlying image as a watermark is proposed in this paper. Firstly, a binary feature map is extracted from the transmitting side as watermark and partitioned into blocks. Secondly, to create a watermarked image, neighboring feature map/watermark blocks are blended and encrypted for insertion. On the receiving side, the feature map from the received image is extracted once again and compared against the recovered watermark to verify integrity and authenticity. In addition to the capability of detecting geometric transformation, removal of original objects and the addition of foreign objects, the proposed scheme is also capable of localizing tampering and detecting cropping without a priori knowledge about the image. This work may be applicable in the areas of military imagery transmission, imaging of micro evidence from crime scenes, and medical image archiving.