Paper 2017/192

Improved Hybrid Consensus Scheme with Privacy-preserving Property

Shuyang Tang, Zhiqiang Liu, Zhen Liu, Yu Long, and Shengli Liu

Abstract

Proof-of-work-based consensus, adopted in Bitcoin, has already drawn much attention from cryptocurrency and block chain community. Despite its nice decentralization prop- erty, it has significant limitation in terms of efficiency since transactions can not be confirmed within seconds. In 2016, hybrid consensus was proposed to partially deal with this issue by introducing committee responsible for validating transactions. However, there still exists some issues with respect to this hybrid consensus such as selfish mining, fairness to the election of committee member, incentives for the consensus scheme, and so on. To improve the hybrid consensus further, we first present a substitution for proof-of-work, named as fair-proof-of-work (fPoW), to solve the issues related to selfish mining and fair committee election. We also demonstrate the incentives for our improved hybrid consensus. Then, based on this consensus, we build privacy-preserving constructions (including identity and content privacy preserving) to make the consensus more applicable and powerful. Finally, we give formal security proof for our newly-proposed consensus scheme. It is expected that this novel consensus scheme could be adopted in block chains which require decentralization, high efficiency, as well as privacy- preserving.