An image authentication system utilizes a coded version of a digital image signature and embeds that information into a transform representation of the image. A digital image signature preferably is extracted from the image data. That signature is coded so that the signature is not immediately recognizable. The coded information is embedded into high frequency coefficients in a transform representation of the image. The contents of the high frequency coefficients of a received or later accessed signal can then be deciphered and compared to the signature determined directly from the image to authenticate the integrity of the signal.