Abstract: We introduce the abstract framework of decentralized smart contracts system with balance and transaction amount hiding property over Account-model blockchain. To build a concrete system with such properties, we utilize a homomorphic public-key encryption scheme and construct a highly efficient non-interactive zero knowledge (NIZK) argument based upon the encryption scheme to ensure the validity of the transactions. Our NIZK scheme is perfect zero knowledge in the common reference string model, while its soundness holds in the random oracle model. Compared to previous similar constructions, our proposed NIZK argument dramatically improves the time efficiency in generating a proof, at the cost of relatively longer proof size.

 

摘要：本文首先提出具有余额和交易金额隐藏性质的分布式智能合约系统的抽象框架，然后利用同态公钥加密方案保护余额和交易金额的机密性，最后设计非交互式零知识证明以支持密态金额的合法性验证，包括余额够减、转账金额非负以及账本均衡。本文设计的非交互式零知识证明在公共参考字符串模型下具有完全零知识性，并在随机预言模型下具备可靠性。与已有的解决方案相比，本文的解决方案虽然牺牲较长证明长度，但可以极大地提高证明生成效率。