Paper 2023/916 Original: eprint.iacr.org/2023/916 ↗

Unlinkability and Interoperability in Account-Based Universal Payment Channels

Abstract

Payment channels allow a sender to do multiple transactions with a receiver without recording each single transaction on-chain. While most of the current constructions for payment channels focus on UTXO-based cryptocurrencies with reduced scripting capabilities (e.g., Bitcoin or Monero), little attention has been given to the possible benefits of adapting such constructions to cryptocurrencies based on the account model and offering a Turing complete language (e.g., Ethereum). The focus of this work is to implement efficient payment channels tailored to the capabilities of account-based cryptocurrencies with Turing-complete language support in order to provide scalable payments that are interoperable across different cryptocurrencies and unlinkable for third-parties (e.g., payment intermediaries). More concretely, we continue the line of research on cryptocurrency universal payment channels (UPC) which facilitate interoperable payment channel transactions across different ledgers in a hub-and-spoke model, by offering greater scalability than point-to-point architectures. Our design proposes two different versions, UPC and AUPC. For UPC we formally describe the protocol ideas sketched in previous work and evaluate our proof-of-concept implementation. Then, AUPC further extends the concept of universal payment channels by payment unlinkability against the intermediary server.