Boomerang: Redundancy Improves Latency and Throughput in Payment-Channel Networks

TL;DR

Boomerang introduces a redundancy-based technique for payment-channel networks that significantly reduces transfer latency and doubles throughput by constructing risk-free redundant paths, leveraging secret sharing and Bitcoin Script implementation.

Contribution

The paper presents Boomerang, a novel method to add redundant payment paths in multi-path routing, improving latency and throughput without risking counterparty funds.

Findings

40% reduction in transfer latency

2x increase in network throughput

Effective implementation in Bitcoin Script

Abstract

In multi-path routing schemes for payment-channel networks, Alice transfers funds to Bob by splitting them into partial payments and routing them along multiple paths. Undisclosed channel balances and mismatched transaction fees cause delays and failures on some payment paths. For atomic transfer schemes, these straggling paths stall the whole transfer. We show that the latency of transfers reduces when redundant payment paths are added. This frees up liquidity in payment channels and hence increases the throughput of the network. We devise Boomerang, a generic technique to be used on top of multi-path routing schemes to construct redundant payment paths free of counterparty risk. In our experiments, applying Boomerang to a baseline routing scheme leads to 40% latency reduction and 2x throughput increase. We build on ideas from publicly verifiable secret sharing, such that Alice learns a secret of Bob iff Bob overdraws funds from the redundant paths. Funds are forwarded using Boomerang contracts, which allow Alice to revert the transfer iff she has learned Bob's secret. We implement the Boomerang contract in Bitcoin Script.