Chameleon Hash Time-Lock Contract for Privacy Preserving Payment Channel Networks

Payment channel networks (PCNs) have been proposed to address the low transaction throughput of the permissionless blockchain protocols. Though the PCNs allow users to have the unlimited number of transactions in the channel without interacting with blockchain, it leaks the entire payment paths to the public. To address the payment path leakage issue, we propose a Chameleon-hash based payment protocol, called Chameleon Hash Time-Lock Contract (CHTLC). Using Chameleon-hash function in a multi-layer fashion guarantees that no user can recover the payment path if at least one intermediate payment node is honest. For the same payment path, compared with Multi-hop Hash Time-Lock Contract (MHTLC) protocol of Malavolta et al. [1], CHTLC is 5 times faster in the payment data initialisation, and the communication bandwidth is reduced significantly from 17, 000KB to just 7.7 KB.