Paper 2024/025

Bitcoin Clique: Channel-free Off-chain Payments using Two-Shot Adaptor Signatures

Siavash Riahi, Technische Universitat Darmstadt
Orfeas Stefanos Thyfronitis Litos, Imperial College London

Blockchains suffer from scalability limitations, both in terms of latency and throughput. Various approaches to alleviate this have been proposed, most prominent of which are payment and state channels, sidechains, commit-chains, rollups, and sharding. This work puts forth a novel commit-chain protocol, Bitcoin Clique. It is the first trustless commit-chain that is compatible with all major blockchains, including (an upcoming version of) Bitcoin. Clique enables a pool of users to pay each other off-chain, i.e., without interacting with the blockchain, thus sidestepping its bottlenecks. A user can directly send its coins to any other user in the Clique: In contrast to payment channels, its funds are not tied to a specific counterparty, avoiding the need for multi-hop payments. An untrusted operator facilitates payments by verifiably recording them. Furthermore, we define and construct a novel primitive, Two-Shot Adaptor Signatures, which is needed for Bitcoin Clique while being of independent interest. This primitive extends the functionality of normal Adaptor Signatures by allowing the extraction of the witness only after two signatures are published on the blockchain.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Major revision. ACNS 2024: 22nd International Conference on Applied Cryptography and Network Security
blockchaincommit-chainBitcoinlayer 2adaptor signatures
Contact author(s)
o thyfronitis-litos @ imperial ac uk
2024-01-08: approved
2024-01-07: received
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      author = {Siavash Riahi and Orfeas Stefanos Thyfronitis Litos},
      title = {Bitcoin Clique: Channel-free Off-chain Payments using Two-Shot Adaptor Signatures},
      howpublished = {Cryptology ePrint Archive, Paper 2024/025},
      year = {2024},
      note = {\url{}},
      url = {}
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