A Public Key Watermark for Image Verification and Authentication

We propose in this paper a public key watermarking algorithm for image integrity veri cation. This watermark is capable of detecting any change made to an image, including changes in pixel values and image size. This watermark is important for several imaging applications, including trusted camera, legal usage of images, medical archiving of images, news reporting, commercial image transaction, and others. In each of these applications, it is important to verify that the image has not been manipulated and that the image was originated by either a speci c camera or a speci c user. The veri cation (the watermark extraction) procedure uses a public key as in public key cryptography, and hence it can be performed by any person without the secure exchange of a secret key. This is very important in many applications (e.g., trusted camera, new reporting) where the exchange of a secret key is either not possible or undesirable.