Copyright protection based on transaction watermarks

Transaction watermarks have distinct codes embedded into different copies of the same content. This enables identification of the path that leads to copyright violation for possible prosecution of violators. Crucial issues in design of transaction watermarks are immunity to collusion attacks and low processing at embedder. These issues are solved in the proposed technique using combination of common and transaction watermarks, and two-step embedding approach. It the first embedding step two or more copies of watermarked material are generated with distinct transaction watermarks. In the second step those copies are cut and spliced to generate new copy for further distribution. Extraction of watermarks is based on detection of common watermarks followed by forensic analysis of transaction watermarks.