Boundless Major Breakthrough! Bitcoin Becomes the Ultimate Settlement Layer for Ethereum ZK Proof

RISC Zero team Boundless launches cross-chain verification system, utilizing BitVM and zero-knowledge proofs to make Bitcoin the settlement verification layer for Ethereum and Base, without altering Bitcoin’s core rules. The system integrates protocols like Citrea, Wormhole, and others, operating from Ethereum mainnet and Base Layer 2 to Bitcoin.

How Boundless Enables Zero-Knowledge Proof Verification on Bitcoin

The core innovation of Boundless lies in its “cross-chain verification system,” allowing users to now verify and permanently settle computationally expensive zero-knowledge proofs on Bitcoin. Zero-Knowledge Proofs (ZK Proofs) are essentially concise receipts used to prove that a complex computation has been completed without revealing transaction details. Developers widely use ZK proofs to scale networks and enhance privacy, making it a key technology that has enabled large-scale practical applications of zero-knowledge cryptography on blockchains.

Boundless CEO Shiv Shankar told The Block: “Fundamentally, this isn’t about turning Bitcoin into Ethereum. Instead, it’s Ethereum-style execution secured by Bitcoin, not running on Bitcoin. Bitcoin acts as the final verifier and settlement layer for zero-knowledge proofs, which can express a lot of complex computations.”

The key to this architecture is separation of duties. Smart contract chains like Ethereum and Base handle complex computations and generate zero-knowledge proofs, while Bitcoin serves as the ultimate arbiter and immutable record layer. This design leverages Bitcoin’s advantages as the most secure and decentralized blockchain, without requiring high-cost computations on Bitcoin itself. For financial applications demanding maximum security, this Bitcoin-backed settlement layer provides an unprecedented trust foundation.

BitVM Unlocks Bitcoin Smart Contract Capabilities Without Changing Consensus

Boundless’s verification system employs Bitcoin Virtual Machine (BitVM), a somewhat controversial verification framework designed for verifying off-chain Bitcoin computations. Proposed in 2023 and launched in mid-2025, BitVM essentially extends some smart contract functionalities to Bitcoin without updating Bitcoin’s core rules or code.

Shankar emphasized: “BitVM unlocks the ability to anchor real computations to Bitcoin, and Boundless is built on this. This capability requires no changes to Bitcoin in any way. That’s the key: the protocol remains unchanged.”

This is crucial. The Bitcoin community is extremely cautious about altering core protocols, and proposals requiring hard forks face significant resistance. The innovation of BitVM lies in its use of Bitcoin’s existing scripting language and opcodes, employing clever cryptographic design to verify off-chain computations without touching Bitcoin’s consensus mechanism. This “conservative innovation” approach allows Boundless to advance technology within the acceptance scope of the Bitcoin community.

Bitcoin lacks a native smart contract virtual machine, and its scripting language is limited and intentionally simple. Shankar explained: “Bitcoin’s verification mechanism is more strict because it’s more honest. You pay to resolve disputes, not for continuous execution.” This design philosophy differs sharply from Ethereum, but it also makes native zero-knowledge proof unlocking on Bitcoin a significant technical challenge. Boundless overcomes this by moving complex computations off-chain and only verifying the final results on Bitcoin.

Integrating Citrea and Wormhole to Build a Cross-Chain Ecosystem

According to the announcement, Boundless also incorporates Citrea, a native Bitcoin-based zero-knowledge proof summarization protocol. Like OP_CTV and other Layer 2 protocols and paradigms, Citrea aims to expand Bitcoin’s functionality. This integration makes Boundless not just a verification system but a comprehensive cross-chain infrastructure.

In August, Boundless integrated with Wormhole, aiming to connect EVM chains like Avalanche and Base to Solana. Wormhole is one of the largest cross-chain messaging protocols, supporting asset and data transfer among dozens of blockchains. Through Wormhole integration, Boundless extends its reach beyond Ethereum ecosystem, bringing Bitcoin’s security to Solana, Avalanche, and other major public chains.

Boundless is supported by RISC Zero’s zkVM proof tools. RISC Zero is a leading developer in the zero-knowledge proof space, whose zkVM allows developers to write verifiable computations in general-purpose programming languages. This versatility significantly lowers development barriers, enabling more applications to leverage zero-knowledge proofs. Boundless plans to “expand support for integration with other chains and ecosystems beyond Ethereum and Base,” laying the foundation for “Bitcoin to become a shared security layer across a broader blockchain ecosystem.”

From Store of Value to Multi-Function Verification Layer Paradigm Shift

Shankar pointed out: “The needs of the Bitcoin ecosystem have shifted from purely being a store of value to verifying more functions without changing consensus. As the L1 payment wars intensify, rollup projects increasingly require a more powerful and neutral settlement layer.”

This statement reveals the market context behind Boundless’s emergence. Bitcoin has long been positioned as “digital gold,” primarily for value storage. However, as blockchain technology matures, the market is exploring how to expand Bitcoin’s functionality while maintaining its core security. Boundless’s solution is: avoid executing complex computations on Bitcoin itself, instead making Bitcoin the final verifier and settlement layer.

This positioning is especially attractive to rollup projects. Currently, most Ethereum Layer 2 solutions publish transaction data and proofs to the Ethereum mainnet, relying on Ethereum’s security. But as competition among Layer 1s heats up, some projects seek more neutral, decentralized settlement layers. Bitcoin, with its largest market cap, most dispersed hash power, and conservative governance, has the potential to become the “settlement layer of settlement layers.” Boundless is turning this potential into reality with key technical innovations.

Shankar acknowledged the technical challenges: “We’re here to do hard things, not easy ones. Bitcoin has no native verification mechanism, so everything must be expressed through Bitcoin’s scripting model.” Nonetheless, he noted that ZK technology has now reached production-level maturity, and is faster, cheaper, and more reliable than ever. This maturity provides the technical foundation for Boundless to implement ZK verification on Bitcoin.

From a broader perspective, Boundless represents a new paradigm of blockchain interoperability. It does not aim to replace existing public chains but leverages their respective strengths: Ethereum and Base offer rich smart contract capabilities, while Bitcoin provides ultimate security. This layered architecture could become the standard model for future multi-chain ecosystems, with Boundless as a pioneer shaping the market’s rules.