Why We're Becoming an Operator on Alpen

Bringing real utility to native Bitcoin

Written by @nicostery

Bitcoin is the most decentralized monetary asset in the world. Yet for over a decade, using it productively by lending it, borrowing against it, or deploying it in DeFi has meant handing it to a custodian and giving up the very properties that make it valuable.

We've been waiting for a solution that doesn't require that compromise. We've found one.

Chainflow is joining Alpen Labs as an operator, helping secure the BTC deposits and withdrawals that move in and out of Alpen's financial ecosystem. Alpen will make Bitcoin-native financial markets possible, delivering real utility for BTC holders.

This partnership reflects a conviction we've held for a long time. Bitcoin deserves real utility, but only the kind that does not ask holders to give up custody to get it.

The Problem: Bitcoin's Trillion-Dollar Lock-Up

Bitcoin is the largest and most liquid digital asset in the world. Yet until now, every serious attempt to make it productive has required handing it over to someone else.

The dominant solution has been custodial wrapped Bitcoin, with products like WBTC and cbBTC. You deposit your real BTC with a custodian, who locks it in a vault and issues you a token that represents it on another blockchain. You can use that token in DeFi, but you no longer hold your Bitcoin. A company does.

In theory, the system works. In practice, it reintroduces exactly the kind of counterparty risk Bitcoin was built to eliminate.

Custody concentration: Every custodial wrapped Bitcoin product ultimately depends on one or a small number of companies holding users' BTC in reserve. A change in management, a shift in custody policy, or a single regulatory action in one jurisdiction can put billions of dollars of user funds at risk. The 2024 restructuring of WBTC's custody model illustrated this clearly: a proposed change to key distribution triggered community backlash and prompted major DeFi protocols to reassess their risk exposure. The issue isn't unique to WBTC. Any centralized custodial model carries it.
Operational fragility: Minting and redeeming custodial wrapped Bitcoin typically requires human approval, compliance checks, and manual or semi-automated reserve management. If the custodian is down, compromised, insolvent, or under regulatory pressure, users can't access their Bitcoin.
Trust, not verification: The entire model rests on the premise that a regulated company will always act honestly and remain solvent. Billions of dollars have been lost to bridge exploits industry-wide, and wrapped tokens remain one of DeFi's largest single points of failure.

The result is a paradox: the most decentralized monetary asset in the world enters financial markets through its most centralized chokepoint.

What Alpen Labs Is Building

Alpen Labs is taking a fundamentally different approach. Instead of wrapping Bitcoin through a custodian, Alpen uses cryptographic proofs to move it, with Bitcoin itself as the source of truth.

The Alpen platform consists of two layers:

Alpen is an execution layer that settles through Bitcoin. Validity proofs, withdrawal data, and block commitments are posted to Bitcoin and verified against it, while full transaction data is relayed off-chain to Alpen nodes. It is EVM-compatible, so developers can build financial applications with familiar tooling.
Strata is the orchestration and bridging layer that handles the movement of BTC between the Bitcoin blockchain and the Alpen execution environment.

What makes this work is Alpen's novel verifier for Bitcoin. Rather than trusting a custodian to be honest, Alpen uses a challenge-response system where anyone on the Bitcoin network can verify whether an operator acted correctly, and slash them financially if they didn't. The verifier runs on garbled circuits, Alpen's Glock-based architecture, which advances beyond earlier BitVM-based designs and keeps the on-chain footprint small. This is what a real advance in Bitcoin programmability looks like: new financial infrastructure that Bitcoin can verify for itself.

So the security of the system does not depend on a majority of trusted parties behaving honestly. It requires only one functional participant to catch and penalize misconduct. This is the 1-of-N assumption: as long as a single operator or challenger is functioning correctly, user funds are safe.

The Research Behind It

What makes Alpen's verifier technically credible is the depth of cryptographic research underpinning it. Two pieces of work stand out.

Glock (Garbled Locks for Bitcoin): Glock introduces a new way to verify computation on Bitcoin using a cryptographic tool called a garbled circuit, a method that lets one party compute a function on encrypted inputs without ever seeing those inputs directly.

In Alpen's case, the function being evaluated is SNARK verification. If an operator makes a false claim about a withdrawal, the evaluated circuit reveals a secret that serves as an automatic fraud proof, allowing the operator's bond to be slashed on-chain. Glock also introduces a specialized designated-verifier SNARK, a very compact cryptographic proof with a simplified verifier, tailored to keep the on-chain footprint as small as possible. That matters enormously given Bitcoin's limited block space.

Mosaic (Practical Malicious Security for Garbled Circuits on Bitcoin): Mosaic solves a critical follow-up problem: how do you ensure the garbled circuit itself was constructed honestly?

In plain terms: a malicious operator could build a rigged circuit that never produces a fraud proof, even when the underlying claim is invalid. Mosaic prevents this using a technique called cut-and-choose. The operator must produce multiple independently garbled copies of the circuit, some of which are opened for inspection, making cheating statistically infeasible. This is combined with adaptor signatures to minimize the amount of data that needs to go on-chain.

Together, Glock and Mosaic represent one of the most advanced research programs for trust-minimized Bitcoin infrastructure in the industry. Both are openly published on the IACR Cryptology ePrint Archive and accompanied by working code.

What It Means to Be an Operator

Operators are the entities that process deposits and withdrawals. When a user wants to move BTC back from Alpen to the Bitcoin chain, an operator fronts the funds from its own balance and is later reimbursed from the bridge deposit pool. This reimbursement is subject to the glock challenge-response game: the operator must prove its claim was valid, and anyone can dispute it.

Operators stake a bond as collateral. If they submit a fraudulent claim, that bond is forfeit, slashed by a challenger and partially awarded as a reward. Operators don't need to pre-fund every withdrawal individually. Their collateral is reusable across multiple withdrawals.

As an operator, Chainflow will run the node infrastructure, maintain staked collateral, and process user withdrawals. By verifying the deposits and withdrawals that move BTC through Alpen, we help secure financial services built around a $1T+ asset. We see this as more than a technical role. It's an opportunity to be part of the foundational infrastructure that brings Bitcoin into a programmable world without compromising on its core principles.

Why This Partnership

We've been watching the Bitcoin financial space and waiting for a solution that didn't require a compromise we weren't willing to make. WBTC asked users to trust a custodian. cbBTC asked users to trust Coinbase. Federated sidechains asked users to trust a committee.

Alpen Labs is the first team we've seen build a solution that genuinely reduces trust to the minimum the technology allows.

It doesn't require a trusted majority. A single functional participant is enough to keep funds safe.
It's backed by openly published cryptographic research. Glock and Mosaic are available on the IACR Cryptology ePrint Archive, the standard venue for cryptographic work.
It's fully open-source. The bridge code, orchestration layer, and execution layer are all publicly available on GitHub.

For our users and clients, this means access to Bitcoin-backed yield, lending, and financial strategies without the custodial risk that has historically come with them. For us, it means doing infrastructure work that's worth doing on Bitcoin.

Looking Ahead

Chainflow is one of a growing set of operators, applications, and infrastructure providers assembling around Alpen ahead of mainnet. The system is under active development and undergoing security audits. As an operator, Chainflow will be live from the Testnet III launch, with mainnet to follow.

For over a decade, Bitcoin has been the world's most secure store of value, but using it productively has always meant giving up the properties that make it valuable. Alpen Labs is changing that equation, and we're proud to be part of it.

If you're interested in what this means for your Bitcoin, or how our infrastructure services work, reach out to us.