The Marriage of Cryptography and Watermarking - Beneficial and Challenging for Secure Watermarking and Detection

摘要

Multimedia applications deploy various cryptographic and watermarking techniques to maintain security. In this context, we survey the main work on two promising approaches for the secure embedding and detection of a watermark in an untrusted environment, and we point out some associated challenges. In the former case we consider Zero-Knowledge Watermark Detection (ZKWMD) that allows a legitimate party to prove to a potentially un-trusted verifying party that a watermark is detectable in certain content, without jeopardizing the security of the watermark. ZKWMD protocols are useful primitives for direct proofs of authorship (i.e., without online involvement of a trusted third party) and dispute resolving in distributed systems. In the latter case we consider a Chameleon-like stream cipher that achieves simultaneous decryption and fingerprinting of data, and can serve as the second line of defense for tracing illegal distribution of broadcast messages, termed as Fingercasting.