Abstract: The present invention is a digital watermarking technique Phasemark™ for image authentication. Using a signature extracted from the original image, the present invention hides an encoded version of the signature back into the original image, forming the watermarked image. The hiding is done in the frequency domain. Specifically, the present invention is a new transform domain digital watermarking technique that hides a signature obtained from the Fourier phases into the magnitude spectrum of the same host image. The detection process computes the discrete Fourier transform of the watermarked image, extracts and decodes the embedded signature, and then correlates it with calculated phase information. Correlation metrics determine the degree of authenticity of the image.

Abstract: In a communication system having a plurality of networks, a method of achieving network separation between first and second networks is described. First and second networks with respective first and second degrees of trust are defined, the first degree of trust being higher than the second degree of trust. Communication between the first and second networks is enabled via a network interface system having a protocol stack, the protocol stack implemented by the network interface system in an application layer. Data communication from the second network to the first network is enabled while data communication from the first network to the second network is minimized.