Abstract :
Most existing watermarking protocols deal with the copyright protection as a transaction between the seller and the buyer. However, these protocols don.t appropriately resolve the copyright problem of copyright authority, copyrighter, ICP and customer. To address this issue, a new watermarking protocol proposed in this article uses three watermarks in structure. By introducing the CA, the signature and the timestamp, the protocol sets up a hiberarchy of digital copyright authorities to protect rights, defends ambiguity attacks and collusive attacks, and resolves the non-repudiation problem and CS overload problem. Because ICP and customer cannot remove the watermark from watermarked digital content, and neither the copyrighter nor the ICP can fabricate piracy, the proposed protocol can trace piracy. With the proxy signature, the digital content transaction without the Third party is performed in which there are only two participants, the seller and the buyer.
