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Formal Verification of a Fail-Safe Cross-Chain Bridge

Authors Filip Marić , Bernhard Scholz , Pavle Subotić

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Subject Classification

ACM Subject Classification
  • Software and its engineering → Software verification
Keywords
  • Cross-Chain Bridge
  • Formal Verification
  • Logic
  • Security

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Abstract

Cross-chain bridges are financial services that interconnect blockchains. High monetary values flow through these bridges, and their security must be safeguarded. However, designing real-world cross-chain bridges is a difficult endeavor. Due to blockchain’s closed-world nature, tokens cannot be transferred from a sender to a receiver chain; on the contrary, they need complex logic that maintains an equilibrium on both chains, even if either the chains or the bridge fail. This paper formally verifies a model of a novel fail-safe cross-chain bridge to ensure correctness. We define formal requirements and prove the bridge is safe using the Isabelle/HOL proof assistant.

Cite As Get BibTex

Filip Marić, Bernhard Scholz, and Pavle Subotić. Formal Verification of a Fail-Safe Cross-Chain Bridge. In 6th International Workshop on Formal Methods for Blockchains (FMBC 2025). Open Access Series in Informatics (OASIcs), Volume 129, pp. 8:1-8:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025) https://doi.org/10.4230/OASIcs.FMBC.2025.8

Author Details

Filip Marić
  • University of Belgrade, Serbia
Bernhard Scholz
  • Sonic Research, Sydney, Australia
Pavle Subotić
  • Sonic Research, Belgrade, Serbia

Acknowledgements

We want to thank Sonic Labs engineers Jan Kalina and Jirka Malek for designing and implementing the fail-safe bridge. Without their insights and explanations, we would not have been able to build the model.

Supplementary Materials

References

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