Fingerprinting for multimedia content broadcasting system

We investigated the traceability of illegal users to prevent illegal redistribution of pirated copies by adopting cryptographic and watermarking approaches. The former approach involves controlling the decryption key sequence issued to users, and the latter involves embedding fingerprint information into multimedia content. Since the cryptographic approach identifies illegal users from the decryption key sequence, a decrypted copy is not protected from illegal redistribution. The watermarking approach can trace illegal users if the fingerprint information is correctly extracted from a pirated copy. However, the transaction of legal distribution is one-to-one in conventional systems. In this paper, we propose a broadcast-type fingerprinting system by introducing a time-bound key management scheme based on the assumption that illegal users must financially compensate to the broadcaster for all content distributed during a certain period. In the proposed system, illegal users can be identified from the decryption key sequence issued to users as well as from pirated copies.