Technical Program

Paper Detail

Paper Title Privacy-Utility Tradeoffs in Payment Channel Network Routing
Paper IdentifierFR3.R1.2
Authors Giulia Fanti, Carnegie Mellon University, United States
Session Information Privacy and Fairness
Location Le Théatre (Parterre), Level -1
Session Time Friday, 12 July, 14:30 - 16:10
Presentation Time Friday, 12 July, 14:50 - 15:10
Abstract Poor scalability is one of the primary challenges preventing broad adoption of blockchains: existing designs typically incur high transaction confirmation latency and exhibit low throughput. Payment channel networks (PCNs) are a leading proposal for improving the scalability of several major cryptocurrencies including Bitcoin and Ethereum. PCNs are an overlay network that enables fast transactions by pre-allocating funds on the blockchain; since the funds are confirmed ahead of time, users do not need to verify every transaction on the blockchain, thereby substantially speeding up transactions. Abstracting the PCN as a graph, whenever Alice wishes to transact with Bob, she only needs to find a path on the graph from herself to Bob with sufficient funds to support her transaction. However, in practice, channel balances are hidden by the protocol for privacy reasons. Hence, in practice, users simply guess whether each path has enough balance or not. In this work, we study privacy-utility tradeoffs associated with revealing noisy path balances. We show upper bounds on the privacy-utility tradeoff, and construct explicit schemes that achieve this upper bound for a broad class of network topologies.