Privacy Preserving Netting Protocol for Inter-bank Payments

Abstract

Banks transfer money and securities instantaneously on a gross basis by utilizing Real-Time Gross Settlement (RTGS) systems. Central banks are in charge of managing and operating RTGS systems, and they require each local inter-bank payment instruction to be processed by them. Accordingly, contemporary RTGS systems face many challenges including unconditional trust and privileges given to the central banks, and the inherent single point of failure vulnerability associated with centralized systems. To address these challenges, some financial institutions are starting to embrace blockchain technology. Project Jasper and Project Ubin are two successful preliminary attempts. However, these projects do not preserve participants’ privacy, and more importantly, they lack liquidity saving mechanisms to resolve the frequently occurring gridlock state. An efficient way to resolve gridlock is to settle payment instructions on a netting basis. In this paper, we propose a decentralized netting protocol that ensures the correctness of the netting result, while hiding the transferred amounts and preserving recipients’ privacy. We evaluate the protocol’s performance on Ethereum and show that the proposed protocol achieves its desired security properties while being feasible to deploy in practice.