Multi-Hop Privacy-Preserving Cross-Chain Payment Channels for Multi-Chain Ecosystems

Multi-hop cross-chain payment channels enable efficient asset transfer in multi-chain ecosystems, but extending single-hop privacy-preserving designs to routed paths faces a fundamental bottleneck: synchronization puzzles must be reused or propagated across hops, which exposes correlation handles to relay nodes and breaks unlinkability. To address this limitation, we propose MP2C, a privacy-preserving multi-hop cross-chain payment channel scheme that extends the atomicity guarantees of P2C2T while preserving unlinkability in multi-hop networks via secure multi-party computation. MP2C integrates multi-party adapter signatures and verifiable timed discrete logarithms to cryptographically bind hop-by-hop asset release and timeout refunds, and incorporates bonding and slashing mechanisms to enhance robustness against aborting or malicious participants. Implementation and evaluation results show that MP2C supports multi-hop cross-chain payments with practical off-chain overhead: compared to P2C2T, it increases per-hop running time by about 17.1% and per-hop communication by about 5.6%, while storage remains lightweight.