A lightweight and anonymous copyright-protection protocol

Gradually, copyright-protection protocols have attracted much attention in that they provide effective copyright protection mechanisms. Asymmetric copyright-protection protocols allow the buyer to know and possess the protected content yet the seller has no idea about it. Subsequently, if an illegal copy is found, the seller can identify the buyer by cooperating with a trusted third party. Most copyright-protection protocols adopt public-key cryptosystems to achieve asymmetry. However, both encryption and decryption of multimedia based on public-key cryptosystems have the drawbacks of requiring high computational complexity and suffering from the burden of maintaining Public Key Infrastructure. Hence, enhancement and further development of these protocols are both necessary and central to the development of future e-commerce. In this paper, a lightweight copyright-protection protocol, benefiting from combining secret-key cryptosystems and a tamper-resistant device, is proposed to provide not only asymmetry of the protocol but also transaction anonymity of the buyer. Since the tamper-resistant device, generally speaking, provides a higher security level and is more and more commonly used, the schemes based on a tamper-resistant device are more practical than before. Moreover, the proposed protocol is computationally efficient and the key management is simple.