Nubit has open-sourced Bitcoin Thunderbolt, an off-chain protocol for transferring Bitcoin UTXO ownership without a payment-channel graph, and said the research paper behind it has been accepted at ACM CCS 2026.
The company account posted the news on Saturday. A matching GitHub release, Bitcoin Thunderbolt v1.0.0, was published the same day under RiemaLabs/thunderbolt. The repository says Nubit maintains the project and that v1.0.0 is the first stable open-source release. The license is Apache 2.0.
Thunderbolt is described as an asynchronous transfer protocol: a UTXO is locked under a public key shared by the current holder and a threshold committee, after which ownership can move off-chain, including when the recipient is offline. The v1.0.0 notes list deterministic ledger state, threshold committee services, encrypted crash recovery, CometBFT finality, and Bitcoin Core reorganization and settlement tooling. The security policy currently says 1.0.x receives fixes for documented regtest and signet environments; the project's own roadmap still places mainnet after further testing and an independent audit.
The academic paper, "Thunderbolt: Fast Asynchronous Off-Chain Bitcoin Transfers," is on the IACR ePrint archive as 2025/709, last revised on 22 August 2026. Authors listed there include Hongbo Wen, Hanzhi Liu, Yanju Chen, Jingyu Ke, Dahlia Malkhi, and Yu Feng. Wen, a Nubit co-founder, posted separately that the work — from Nubit and UC Santa Barbara — had been accepted at CCS 2026.
Nubit said Thunderbolt has been live for more than a year since an April 2025 unveil, and it attributed to the protocol more than $1 billion in settled transaction value, more than 10 million transactions, and more than 100,000 users. Those operating figures come from the company and were not independently verified for this article.
No major business or technology outlet appears to have covered Saturday's open-source release or the CCS acceptance.