Paper 2020/1441

PayMo: Payment Channels For Monero

Sri AravindaKrishnan Thyagarajan, Carnegie Mellon University
Giulio Malavolta, Max Planck Institute of Security and Privacy
Fritz Schmidt, Friedrich Alexander Universität Erlangen-Nürnberg
Dominique Schröder, Friedrich Alexander Universität Erlangen-Nürnberg

Decentralized cryptocurrencies still suffer from three interrelated weaknesses: Low transaction rates, high transaction fees, and long confirmation times. Payment Channels promise to be a solution to these issues, and many constructions for real-life cryptocurrencies, such as Bitcoin, are known. Somewhat surprisingly, no such solution is known for Monero, the largest privacy-preserving cryptocurrency, without requiring system-wide changes like a hard-fork of its blockchain. In this work, we close this gap by presenting \textsc{PayMo}, the first payment channel protocol that is fully compatible with Monero. \textsc{PayMo} does not require any modification of Monero and can be readily used to perform off-chain payments. Notably, transactions in \textsc{PayMo} are identical to standard transactions in Monero, therefore not hampering the coins' fungibility. Using \textsc{PayMo}, we also construct the first fully compatible secure atomic-swap protocol for Monero: One can now securely swap a token of Monero with a token of several major cryptocurrencies such as Bitcoin, Ethereum, Ripple, Cardano, etc. Before our work, it was not known how to implement secure atomic swaps protocols for Monero without forcing a hard fork. Our main technical contribution is a new construction of an efficient verifiable timed linkable ring signature, where signatures can be hidden for a pre-determined amount of time, in a verifiable way. Our scheme is fully compatible with the transaction scheme of Monero and it might be of independent interest. We implemented \textsc{PayMo} and our results show that, even with high network latency and with a single CPU core, two regular users can perform up to 93500 payments over a span of 2 minutes (the block production rate of Monero). This is approximately five orders of magnitude improvement over the current payment rate of Monero.

Note: To Appear at ESORICS 2022

Available format(s)
Cryptographic protocols
Publication info
Digital Signatures RSA Blockchain Monero Payment Channels Atomic Swaps Verifiable Timed Signatures
Contact author(s)
t srikrishnan @ gmail com
giulio malavolta @ hotmail it
fritz schmid @ fau de
dominique schroeder @ fau de
2022-09-12: last of 3 revisions
2020-11-19: received
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Creative Commons Attribution


      author = {Sri AravindaKrishnan Thyagarajan and Giulio Malavolta and Fritz Schmidt and Dominique Schröder},
      title = {PayMo:  Payment Channels For Monero},
      howpublished = {Cryptology ePrint Archive, Paper 2020/1441},
      year = {2020},
      note = {\url{}},
      url = {}
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