OPRE: Towards Better Availability of PCNs Through Recovering

Minze Xu, Yue Li, Chenglu Shi, Yuan Zhang, Yongchuan Niu, Fengyuan Xu, Sheng Zhong

Abstract: The Payment Channel Network (PCN) stands out as one of the most promising technologies for scaling blockchain-based cryptocurrencies. However, a noteworthy challenge arises during the utilization of PCNs, where a substantial portion of payment channels gradually becomes exhausted, leading to a reduction in the overall availability of PCNs. This issue is crucial in the context of blockchain off-chain PCNs and warrants a comprehensive investigation. In this paper, we introduce the problem of optimal recover and propose OPtimal REcovering protocols, denoted as OPRE and OPRE+, to address this challenge. The protocols target at recovering the optimal number of nearly exhausted channels in the PCN. OPRE provides a basic solution, and OPRE+ is an augmentation which provides a more efficient and effective solution. Furthermore, to address users’ privacy concerns, we propose privacy-preserving versions of the protocols, ensuring that users’ balance on payment channels remains undisclosed during the execution of the protocols. Beyond the theoretical design and analysis, we implement these protocols and conduct experimental evaluations to assess their performance. The results affirm that our protocols exhibit efficiency and effectiveness in significantly improving the availability of PCNs.