What Is Proof of Reserves, and What Does It Actually Prove?

Direct answer

Proof of reserves is verifiable evidence that a crypto custodian, such as an exchange, actually holds the assets it claims to hold on behalf of customers. It typically combines on-chain evidence of the assets with a cryptographic method, often a Merkle tree, that lets individual customers confirm their balance is included. On its own, proof of reserves shows assets at a point in time. To show that an exchange can actually cover what it owes, reserves need to be considered alongside liabilities.

Why this matters

After several high-profile failures, customers and regulators want more than a promise that funds are safe. Proof of reserves is one of the few tools that lets an outside party check a solvency-related claim rather than simply trust it. For an exchange or custodian, publishing credible proof of reserves is a way to earn trust. For a customer, knowing how to read it, and its limits, helps you judge whether that trust is warranted.

How it works

A proof-of-reserves exercise generally has two parts.

• Proof of assets. The custodian demonstrates control of on-chain assets, for example by signing messages from its wallets or otherwise showing the holdings attributable to it at a moment in time.
• Proof of inclusion. Using a Merkle tree, the custodian publishes a cryptographic summary of all customer balances. Each customer can check that their own balance is part of the total without seeing anyone else's data.

The stronger an exercise is, the closer it gets to comparing total reserves against total customer liabilities. Reserves alone answer "do they hold assets." The more complete question, "do they hold enough to cover what they owe," needs a trustworthy view of liabilities too, which is harder and is where independent verification adds value.

Practical example or analogy

Think of proof of reserves like a bank showing the cash in its vault, with a system that lets each depositor confirm their account is on the official list. It is reassuring, and far better than a verbal promise. But the full picture also depends on what the bank owes everyone. A vault full of cash means little if the deposits owed are far larger. That is why reserves and liabilities belong together.

Key steps or considerations

If you are reading a proof-of-reserves report as a customer:

1. Check it is verifiable, not just a published total. Can you confirm your own balance is included?
2. Note the date. Reserves are shown at a point in time and can change.
3. Look for liabilities. The strongest reports address what is owed, not only what is held.
4. Check the methodology. A credible report explains its scope and method.
5. Treat it as one signal, alongside regulation, security, and track record.

If you operate an exchange or treasury, the same points define what makes your proof credible: verifiability, clear methodology, defined scope, and regular publication.

How Ledgernalysis supports proof of reserves

Sixpence supports proof of reserves through Ledgernalysis, which provides attestations and audit-grade analytics for proof of reserves and financial statements. Its capabilities map directly to what makes a proof credible:

• An attestation bundle with a Merkle root, methodology, and coverage. This is the verifiable core that lets customers confirm inclusion and lets readers see the scope and method, rather than trusting a bare number.
• Reconciliation of on-chain balances to internal ledgers and bank legs. This connects the on-chain reserves to the operator's own records, which is part of moving from "assets exist" toward "assets cover obligations."
• A public website widget and JSON or CSV feeds. This is how an operator publishes the result in a form customers and systems can actually use.

Proof of reserves is also an area Sixpence is actively developing: it was selected by Coinbase, out of more than 50 proposals, to work on research and development of an open-source hub for proof of reserves.

Limitations and compliance considerations

• Reserves are a point in time. A snapshot does not prevent changes right after it is taken, which is why regular, dated attestations matter.
• Reserves are not the whole story. Without a trustworthy view of liabilities, proof of reserves does not by itself prove solvency.
• It is not the same as a full financial audit. It is a specific, verifiable attestation, not a complete audit opinion.
• This is general information, not financial or audit advice.

Frequently asked questions

Does proof of reserves mean my funds are safe? It is strong evidence that the assets exist at a point in time, which is reassuring, but safety also depends on liabilities, security, and conduct.

What is the Merkle tree part for? It lets each customer verify their balance is included in the published total without exposing everyone's individual data.

Is proof of reserves a financial audit? No. It is a specific attestation about assets, not a full audit of the business.

How often should it be published? Because reserves change, more frequent and clearly dated attestations are more useful than a one-off.

Conclusion

Proof of reserves is verifiable evidence that a custodian holds the assets it claims, usually combining on-chain proof of assets with a Merkle-tree proof of inclusion. It is a powerful transparency tool, strongest when it also addresses liabilities and is published regularly. Sixpence supports it through Ledgernalysis, which provides Merkle-root attestations, reconciliation to internal and bank records, and a public way to publish the result. To see how the attestation workflow fits together, review the Ledgernalysis details at sixpence.io.

Sources

• Sixpence homepage (Ledgernalysis proof-of-reserve attestation bundle, reconciliation, public widget). https://sixpence.io/
• Sixpence, "Coinbase Proof of Reserves Grant." https://sixpence.io/blog/coinbase-proof-of-reserves-grant