Abstract: In order to solve the problems that copyright owners maliciously frame purchasers and purchasers know their own watermarks but remove them during the digital content copyright protection and tracking process, digital content copyright protection and fair tracking scheme based on blockchain was proposed. First, the Paillier homomorphic encryption algorithm and key distribution smart contract were used to change the purchaser's watermark in the ciphertext state, and the watermark was embedded in the encrypted digital content. Second, the key distribution smart contract and arbitration smart contract were called by the verification node in the blockchain, which solves the single point of failure problem in traditional copyright protection solutions. The experimental results show that when the digital content size is 512x512, compared with blockchain-enabled accountability mechanism against information leakage in vertical industry services, the total execution time of encryption and watermark embedding of the proposed framework is reduced by 98.58%, and the total decryption execution time is reduced by 94.82%. The proposed framework has better efficiency and lower operating cost, and can be widely used in the field of digital content copyright protection.

Key words: blockchain, copyright protection, fair tracking, Paillier homomorphic encryption algorithm, smart contract

摘要： 针对数字内容版权保护和追踪过程中的版权所有者恶意诬陷购买者，以及购买者知道自己的水印而对水印进行去水印操作的问题，提出基于区块链的数字内容版权保护和公平追踪方案。首先，使用Paillier同态加密算法和密钥分发智能合约进行密文状态下购买者的水印更改，并将水印嵌入加密的数字内容。其次，通过区块链中的验证节点来调用密钥分发智能合约和仲裁智能合约，解决了传统版权保护方案存在的单点故障问题。实验结果表明，该研究工作在数字内容尺寸为512x512时，与针对垂直行业服务信息泄露的区块链问责机制相比，该工作加密和嵌入水印的总时间降低了98.58%，总解密时间降低了94.82%。该研究工作的总时间和运行成本开销很低，具有良好的运行效率，能够广泛用于数字内容版权保护领域。

关键词: 区块链, 版权保护, 公平追踪, Paillier同态加密算法, 智能合约