Patent ID: 6532541
Filing Date: 2003-03-11
Classification: G06T,H04L,H04N

Abstract:
A system for authentication of a present digital image, comprising:a signature generator, said signature generator including: an image analyzer, said image analyzer receiving an original digital image, parsing the image into image block pairs and generating invariant features of said image based on a relationship between corresponding DCT coefficients in said at least one image block pair, said relationship between corresponding DCT coefficients including the polarity of the difference of discrete cosine transform coefficients of corresponding coefficients locations in said image block pairs and the magnitude of the difference of discrete cosine transform coefficients of corresponding coefficients locations in said image block pairs; and an encryption processor, said encryption processor encoding the invariant features generated by said image analyzer in accordance with encryption key data to provide an encrypted signature for the original image; and an authentication processor, said authentication processor receiving a present digital image to be authenticated and an encrypted signature for the original image, said authentication processor including: a decryption processor, said decryption processor receiving the encrypted signature and decoding the signature in accordance with decryption key data to extract the invariant features of the original image; means for extracting coefficients of the present image to be authenticated; and an authentication comparator, said authentication comparator receiving the coefficients of the present image to be authenticated, extracting invariant features of the present image from the coefficients, comparing the invariant features from the original image to those of the present image and providing a signal indicative of an authentication failure if the corresponding features do not substantially match.