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Computing on Bitcoin #45
June 27, 2025 - Week 26

Welcome to a fresh edition of Computing on Bitcoin News—your weekly roundup of the latest innovations that keep on pushing Bitcoin beyond.
From trustless bridges to scalable computation and new smart contract models, the ecosystem is evolving fast.
We’re here to share the key updates and breakthroughs so you can stay ahead.
Let’s dive in 🚀

01
Garbled Circuits: the next big thing in Bitcoin scalability

Fairgate's Jony Altszul breaks down why it matters for BitVMX: reduced onchain costs, simpler interactions, and faster execution.

02
BitVM2 Powers Trustless Bitcoin Bridges with Mainnet Verification

Robin Linus and co-authors present "Bridging Bitcoin to Second Layers via BitVM2," a significant advance toward trustless Bitcoin bridges. It introduces BitVM2-core for Turing-complete execution on Bitcoin with a 1-of-n trust assumption. The protocol supports light-client bridging and permissionless fraud-proofing, with a full challenge verification already tested live on mainnet. The paper also cites BitVMX and the TOOP protocol as related developments.

bitvm.org
🔗 BitVM3: Efficient Computation on Bitcoin

A holy grail in blockchain infrastructure is a trustless bridge between Bitcoin and its second layers or other chains. We make progress toward this vision by introducing the first light-client based Bitcoin bridge.At the heart of its design lies BITVM2-CORE, a novel paradigm that enables arbitrary program execution on Bitcoin,combining Turing-complete expressiveness with the security of Bitcoin consensus.

03
Union Bridge Enables BTC-to-Rootstock Transfers with BitVMX

Jonatan Altszul, CEO of Fairgate Labs, unveils Union Bridge, a BitVMX-based, trust-minimized bridge from Bitcoin to Rootstock. It enables decentralized BTC transfers using optimistic fraud proofs, watchtower validation, and a novel Rootstock super-chain for scalable verification.

fairgate.io/blog
🔗 Union Bridge: A Trust-Minimized Bitcoin Bridge

Cross-chain interoperability is a critical challenge in the blockchain ecosystem, especially when it comes to bridging Bitcoin with other networks. Existing solutions often rely on centralized intermediaries, exposing users to counterparty risks and censorship concerns. At Fairgate, in collaboration with Rootstock Labs, we set out to tackle this issue by developing the Union Bridge —a trust-minimized bridge, based on BitVMX, between Bitcoin and Rootstock.

04
GOAT Network Scales BitVM3 Using Label Forward Propagation

GOAT Network’s new paper, “Instantiating BitVM3 from Label Forward Propagation,” introduces a scalable implementation of BitVM3. It enables reusable garbled circuits via label-forward propagation, slashing off-chain data from hundreds of gigabytes to megabytes.
📜Paper

goat.network/blog
🔗 GOAT Network Brings BitVM3 into Practical Use, Pioneering Scalable Native ZK Verification on Bitcoin

Building on BitVM3’s RSA-encrypted Garbled Circuit scheme, GOAT Network introduces a novel Label Forward Propagation method that enables circuit homomorphism and sub-circuit reuse. This breakthrough achieves unlimited reusability of Garbled circuits, dramatically reducing the volume of off-chain data required for on-chain verification. It addresses two major bottlenecks in the original BitVM3 and Delbrag designs: the single-use constraint and the terabyte-scale data footprint, unlocking true scalability for native zero-knowledge computation on Bitcoin.

05
Running Cardano Contracts on Bitcoin via BitVMX + RISC-V

Riley Kilgore, from IOG, discusses compiling Cardano’s smart contract language (UPLC) to RISC-V, enabling direct execution on Bitcoin via BitVMX. This allows running Cardano contracts on Bitcoin with standard Bitcoin transactions and bridges, enhancing Bitcoin DeFi without compromising decentralization.

Beyond HODLing: How Bitcoin Can Now ‘Travel’ Without Trust Issues - Yovela Luo, Co-founder of Fiamma

@Andrew Westberg
Talk with Riley Kilgore from IOG about running Cardano smart contracts directly on bitcoin.

06
Citrea Calls for Bitcoin-Native Apps in ₿app Manifesto

Citrea’s ₿app Manifesto advocates for Bitcoin-native apps that eliminate custodians and unlock BTC’s on-chain utility. It highlights infrastructure like BitVM bridges and ZK proofs enabling non-custodial, modular apps secured by Bitcoin.

blog.citrea.xyz
🔗 A ₿app Manifesto

Bitcoin was introduced as a liberating technology for borderless and censorship-resistant money. Yet in 2025, Bitcoin finds itself surrounded by custodians and increasingly treated as a passive store of value. The Bitcoin network is being sidelined, and its role in decentralized and censorship-resistant finance is being undermined.

07
BOB Brings Secure Bitcoin DeFi via BitVM2 Interoperability

BOB merges Bitcoin’s unmatched security with Ethereum’s powerful DeFi ecosystem, enabling users to access advanced financial tools without sacrificing decentralization or trust. It unlocks native Bitcoin DeFi by leveraging BitVM2 for secure, trust-minimized interoperability.

validatus.medium.com
🔗 BOB: Merging Bitcoin’s Security with Ethereum’s DeFi

The current state of Bitcoin in DeFi is fundamentally broken. Users are frequently forced to deposit BTC into centralized exchanges, lose control or utilize synthetic wrappers like WBTC and tBTC, which depend on multisignature bridges with differing levels of trust. These constructs not only go against Bitcoin’s self-sovereign ethos but also introduce exposures and fragmentation.

That’s a wrap for this week’s Computing on Bitcoin News.
Thanks for following along as the Bitcoin ecosystem steadily evolves.
We’ll be back next Friday with more insights from the frontier of Bitcoin computing.
The Fairgate Team

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