In the world of Bitcoin bridges and interoperability, nBTC stands out as one of the most secure and trust-minimized solutions, with a clear trajectory towards becoming a trustless protocol. While many other protocols claim to be trustless, they often still rely on third-party validators or multisig mechanisms that introduce varying degrees of trust risk. In contrast, nBTC brings Bitcoin to DeFi in a truly trust-minimized, and soon trustless way.

‍About nBTC

nBTC is one of the two models that we at Native are set to release. It represents 1:1 the native Bitcoins on the Bitcoin network, offering a seamless way to integrate Bitcoin into the broader DeFi ecosystem. The second model is dWallet BTC, which operates native Bitcoin on the Bitcoin network within a Zero Trust Architecture.

Trust Models in Blockchain Architecture

In our previous discussions about Trust Models in Blockchain, we've outlined the key distinctions between trustless and trust-minimized designs, particularly for interoperability and bridges. This article delves deeper into these concepts and clarifies why nBTC should be seen as a highly trust-minimized model that is on the path to being fully trustless.

‍Comparative Analysis: Trustless vs. Trust-Minimized Implementations

When it comes to cross-chain bridges, there is a noticeable spectrum between trustless and trust-minimized designs.

Trustless Bridges:

• Trustless bridges use technologies like Zero-Knowledge Proofs (ZKPs) and light clients to enable asset transfers across chains without requiring third-party validators.
• Example: A bridge using Ethereum's consensus proofs to verify Bitcoin transactions would need Bitcoin light nodes on Ethereum and ZKPs to validate transaction inclusion but that's only one part of the bridge. We would need the full verification on the Bitcoin side, that is not possible today.... or non-collusive and trustless MPC - the one that we are heading into.
• Security Assumption: Users trust the cryptographic soundness of the ZKPs and the economic security of both chains.

Trust-Minimized Bridges:

• Trust-minimized bridges relay on additional assumptions or third party, like federated validator sets, with stake slashing to reduce, but not eliminate, trust in relayers.
• Example: A bridge with 100 bonded validators, where 67 must collude to steal funds, uses game-theoretic penalties to deter malicious behavior.
• Security Assumption: Users rely on the assumption of an honest majority among validators and robust fraud-proof systems.

How nBTC Fits the Trust-Minimized Spectrum

While many of today's bridges are labeled as "trustless," the reality is that they still introduce trust assumptions—whether it's through centralized third-party signers, multisig setups, or centralized governance.

nBTC, however, is positioned on the far end of the trust-minimized spectrum, moving closer to trustlessness as it evolves. Here's how:

1. Decentralization & Permissionlessness:
   
   • No third-party required: nBTC operates directly between the Bitcoin and Sui networks, with no intermediary required. Bitcoin executes the transfer, while Sui facilitates the operation within its ecosystem. Learn more about Bitcoin SPV here.
   • Both Bitcoin and Sui are decentralized and permissionless, inheriting these qualities into nBTC.‍
2. Self-Sovereign Verification: nBTC leverages the inherent decentralized nature of both Bitcoin and Sui to enable permissionless verification. Any user can independently verify the process, completely removing reliance on third parties. Leran more about Bitcoin relayer here.
3. ‍Consensus Mechanism: Both Bitcoin and Sui utilize decentralized consensus mechanisms, ensuring the correctness and security of the process without centralized control.‍
4. Transparency & Audibility: All transactions are fully transparent and auditable. Users can verify transactions directly on Bitcoin and Sui without needing third-party systems or proofs, reinforcing the system's trust-minimized nature.

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What’s Missing?

nBTC is progressing towards a fully trustless model, and a key component in this journey is the Zero Knowledge Proofs (ZKPs) mechanism. This will enable a fully permissionless exit mechanism, further minimizing any reliance on third parties. We’re actively working on this feature, which will make nBTC the first truly trustless solution for bringing Bitcoin to DeFi.

Not All Bridges Are Created Equal

• BitVM2 and similar protocols, despite being considered trust-minimized, still involve potential trust risks due to their reliance on exit mechanisms and centralized components, such as sequencers and fraud proofs. Learn more about it here.
• Existing solutions like tBTC, sBTC, BOS, and Rootstock all rely on third-party signers or multisig setups, which fall short of the Zero Trust or Trust less standards.

Is There Any Bitcoin Bridge Compliant with Zero Trust Architecture?

As of March 2025, no Bitcoin bridge is Trustless. Every existing Bitcoin bridge relies on third-party signers (like multisig or MPC), which introduce trust assumptions. Even newer solutions, such as BitVM2, are trust-minimized but still have some vulnerabilities to address.

Native, powered by Ika, will be the first Bitcoin interoperability solution to fully comply with the Zero Trust Architecture!

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Conclusion

In an ecosystem full of bridges that claim to be trustless but rely on third-party validators or centralized mechanisms, nBTC offers a more secure and decentralized solution. With its trust-minimized approach that is steadily moving towards full trustlessness, nBTC represents the future of Bitcoin in DeFi. Stay tuned for more updates as we continue to enhance and finalize nBTC's Zero Trust features.

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