Achieving computational and unconditional security in authentication watermarking: analysis, insights, and algorithms

This paper focuses on the analysis and enhancement of watermark-based security strategies for multimedia authentication. Based on an authentication game between a transmitter and its authorized receiver, and an opponent, security of authentication watermarking is measured by the opponent’s inability to launch a successful attack. In this work, we consider two traditional classes of security for authentication: computational security and unconditional security. First we identify authentication watermarking as an error detection problem, which is different from error correction coding in robust watermarking. Then we analyze the computational and unconditional security requirements of an error detection code structure associated with quantization-based authentication watermarking schemes. We propose a novel security enhancement strategy that results in efficient and secure quantization-based embedding and verification algorithms. For computational security, cryptographic message authentication codes are incorporated while unconditional security is obtained by using unconditionally secure authentication codes. Both theoretical analysis and experimental results are presented. They show that using our approach, protection is achieved without significant increase in embedding distortion, and without sacrificing computational efficiency of the embedding and verification algorithms.