FlexiPCN: Flexible Payment Channel Network

Payment Channel Network (PCN) is a widely recognized and effective off-chain solution used to reduce on-chain operational costs. PCN is designed to address the scalability challenge and throughput issues in permissionless blockchains. Though transaction throughput is improved, many issues remain, like no flexibility, channel exhaustion, poor sustainability, etc. A separate deposit is required for each payment channel between two users, which locks a substantial amount of coins for a long period of time. Therefore, the flexibility to move these locked coins across channels is impossible through off-chain. Moreover, the channels get exhausted due to unbalanced (unidirectional) transfer. This causes the channel to become unsustainable (dead) until the PCN is rebalanced. This work presents a novel payment protocol called Flexible Payment Channel Networks (FlexiPCN), which allows users to deposit coins per user rather than per channel. So, users can move coins flexibly from one channel to another without the help of the blockchain or setting the cycle off-chain. FlexiPCN has been proven to be secure under the Universal Composability framework.