ElasticPay: instant peer-to-peer offline extended digital payment system

Abstract

The paper-based currency system is inherently plagued with several problems, such as: counterfeiting, anonymity about possession, environmental negative impact, etc. Though Central Bank Digital Currency addresses most of these problems, its prerequisite of continuous internet connectivity makes it inefficient in situations of poor connectivity and internet blackout. In this thesis, we propose a novel Peer-to-Peer Offline Payment System. Leveraging Trusted Platform Module (TPM), Trusted Execution Environment (TEEs) and Secure Element (SE) available on mobile phones, our proposed system ensures: complete transaction privacy, unforgeability, non-repudiation, verifiability and eliminates: double spending and anonymity. Moreover, it enables immediate fund settlement and incorporates robust recovery mechanisms. We demonstrate the above properties with experiments. Thus our system advances secure and inclusive CBDC ecosystems by enabling offline P2P transactions, even in the scenarios of limited or no internet access.