[Resource Topic] 2025/709: Thunderbolt: A Formally Verified Protocol for Off-Chain Bitcoin Transfers

Welcome to the resource topic for 2025/709

Title:
Thunderbolt: A Formally Verified Protocol for Off-Chain Bitcoin Transfers

Authors: Hongbo Wen, Hanzhi Liu, Jingyu Ke, Yanju Chen, Dahlia Malkhi, Yu Feng

Abstract:

We present Bitcoin Thunderbolt, a novel off-chain protocol for asynchronous, secure transfer of Bitcoin UTXOs between uncoordinated users. Unlike prior solutions such as payment channels or the Lightning Network, Bitcoin Thunderbolt requires no prior trust, direct interaction, or continuous connectivity between sender and receiver. At its core, Bitcoin Thunderbolt employs a Byzantine fault-tolerant committee to manage threshold Schnorr signatures, enabling secure ownership delegation and on-chain finalization.

Our design supports recursive, off-chain UTXO transfers using tweakable, verifiable signature components. The protocol tolerates up to f malicious nodes in a 3f+1 committee and ensures correctness, consistency, and one-time spendability under asynchronous network conditions.

We formally verify Bitcoin Thunderbolt’s key security properties, namely, unforgeability, ownership soundness, and liveness—using the Tamarin prover. Our results demonstrate that Thunderbolt provides robust, scalable, and non-interactive off-chain Bitcoin transfers, significantly expanding the practical utility of Bitcoin for decentralized applications.

ePrint: https://eprint.iacr.org/2025/709

See all topics related to this paper.

Feel free to post resources that are related to this paper below.

Example resources include: implementations, explanation materials, talks, slides, links to previous discussions on other websites.

For more information, see the rules for Resource Topics .