Clementine: A Collateral-Efficient, Trust-Minimized, and Scalable Bitcoin Bridge

Ekrem Bal; Lukas Aumayr; Atacan İyidoğan; Giulia Scaffino; Hakan Karakuş; Cengiz Eray Aslan; Orfeas Stefanos Thyfronitis Litos

Paper 2025/776

Clementine: A Collateral-Efficient, Trust-Minimized, and Scalable Bitcoin Bridge

Ekrem Bal, Citrea

Lukas Aumayr

, Common Prefix, University of Edinburgh

Atacan İyidoğan, Citrea

Giulia Scaffino

, Common Prefix, TU Wien

Hakan Karakuş, Citrea

Cengiz Eray Aslan, Citrea

Orfeas Stefanos Thyfronitis Litos

, Common Prefix, Imperial College London

Abstract

This whitepaper introduces Clementine, a secure, collateral-efficient, trust-minimized, and scalable Bitcoin bridge based on BitVM2 that enables withdrawals from rollups or other side systems to Bitcoin. Clementine proposes a new Bitcoin light client that remains secure against adversaries controlling less than 50% of Bitcoin’s hash rate, assuming at least one honest Watchtower in a permissioned set. The protocol is collateral-efficient, reusing locked funds over time and reducing unnecessary dust outputs through the strategic use of 0-value outputs, and scalable, enabling a single challenge per Operator to slash multiple misbehaviors. This increases throughput and reduces on-chain load without compromising security. Clementine enables trust-minimized and efficient peg-outs from Citrea to Bitcoin, making zk-rollups on Bitcoin practical and unlocking new paths for native scalability and interoperability.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Preprint.
Keywords: Bitcoin BitVM Light Client Bridge Rollup Blockchain
Contact author(s): ekrem @ chainway xyz
lukas @ commonprefix com
atacan @ chainway xyz
giulia @ commonprefix com
hakan @ chainway xyz
eray @ chainway xyz
orfeas litos @ hotmail com
History: 2025-05-02: revised; 2025-04-30: received; See all versions
Short URL: https://ia.cr/2025/776
License: CC BY

BibTeX

@misc{cryptoeprint:2025/776,
      author = {Ekrem Bal and Lukas Aumayr and Atacan İyidoğan and Giulia Scaffino and Hakan Karakuş and Cengiz Eray Aslan and Orfeas Stefanos Thyfronitis Litos},
      title = {Clementine: A Collateral-Efficient, Trust-Minimized, and Scalable Bitcoin Bridge},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/776},
      year = {2025},
      url = {https://eprint.iacr.org/2025/776}
}