ISSN 1000-1239 CN 11-1777/TP

Journal of Computer Research and Development ›› 2015, Vol. 52 ›› Issue (10): 2304-2312.

Special Issue: 2015网络安全与隐私保护研究进展

### A Trustee-Based and Efficient Divisible E-Cash Scheme

Yu Yulei1, Dong Xiaolei2, Cao Zhenfu2

1. 1(Department of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240);2(Shanghai Key Laboratory for Trustworthy Computing, East China Normal University, Shanghai 200062)
• Online:2015-10-01

Abstract: Divisible e-cash systems allow users to purchase a coin of value 2\+l and spend it part by part. This system not only need to ensure the anonymity of users, but also can detect double-spending behavior from malicious user. In 2015, Canard presented the first efficient divisible e-cash system in both random oracle model and standard model. In the system, for the coin of value 2\+l, the deposit protocol involves up to 2\+l pairing operations. When the value of coin is big, the divisible e-cash system will face challenges. If the value is 2\+{20}, the system will withstand huge computation pressure; if the value is 2\+{30}, it will be a state of collapse. For these potential shortcomings, independent of the work of Canard, we propose a more efficient divisible system based on a trusted third-party, as an improved version of Canard’s system. In the scheme, we make use of a trusted third-party, and reduce the number of public parameters and the number of zero-knowledge proof. Especially in the deposit operation, the complexity of deposit protocol is a linear correlation with l, which provides the possibility for solving the problem of large electronic cash.

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