Paper 2025/1392 Original: eprint.iacr.org/2025/1392 ↗
FLEX — Capital-Efficient Optimistic Bridges with On-Demand Security Bonds for Bitcoin
Abstract
This paper presents FLEX (Fraud proofs with Lightweight Escrows for eXits), a garbled circuit-based protocol designed to facilitate two-party disputes on Bitcoin without requiring permanent security bonds. FLEX enables conditional security deposits that are only activated in the event of a dispute, reducing the financial overhead for both parties. The main goal of FLEX is to improve the capital efficiency of BitVM-based bridges in a permissioned challenge setting but can also be used to improve the security of any other fraud proof-based protocol such as payment channels. The paper also introduces enhancements that allow faster reimbursements in scenarios where one party's node is unavailable, while preserving security and minimizing race conditions.
Metadata
- Available format(s)
PDF- Category
- Cryptographic protocols
- Publication info
- Preprint.
- History
- 2025-08-21: last updated
- 2025-07-31: published
- Short URL
- https://ia.cr/2025/1392
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2025/1392,
author = {Sergio Demian Lerner and Ariel Futoransky},
title = {FLEX — Capital-Efficient Optimistic Bridges with On-Demand Security Bonds for Bitcoin},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/1392},
year = {2025},
url = {https://eprint.iacr.org/2025/1392}
}