Key takeaways
- With one key, whoever holds it controls the Bitcoin. Multi-signature requires several keys to approve a spend, so there is no single point of failure.
- The rule is enforced by the Bitcoin network, not by a company's promise.
- CoinCorner says its Vault keys are held by CoinCorner and AnchorWatch across multiple jurisdictions. The number of keys and the signing threshold are not published.
- Multi-signature protects against key theft and loss. It does not protect against price falls, scams you approve or the failure of a custodian.
- CoinCorner is not regulated by the FCA, and the Vault is not covered by the FSCS or the Financial Ombudsman Service. Its insurance applies only on its stated terms.
For information only. Not investment advice. Don't invest unless you're prepared to lose all the money you invest.
The short answer
A multi-signature (multi-sig) Vault protects your keys by making sure no single key can move your Bitcoin. Several private keys are created, held by different parties in different places, and a set number of them must sign each withdrawal. Stealing or losing one key is therefore not enough to take or strand the funds, which is the weakness of an ordinary single-key wallet.
This guide explains the idea in general terms and then describes what CoinCorner has published about its own Vault. If you are new to keys and wallets, start with what Bitcoin is and how it works.
The problem: one key, one point of failure
Bitcoin ownership is control of a private key, a secret number that produces the digital signature the network needs before it will move coins. Whoever holds that key can spend, and a Bitcoin payment cannot normally be reversed. If the key is lost, the coins are generally lost too, because the network has no reset process.
That makes a single key a single point of failure in two directions. If it is stolen, the thief can empty the wallet. If it is destroyed or forgotten, nobody can. Backups reduce the second risk but add copies that can themselves be stolen. Multi-signature is a way of dividing this risk rather than concentrating it in one secret.
How multi-signature works
In a multi-sig wallet, the coins are locked to a rule that names several public keys and a number of signatures needed. This is usually written M-of-N: N keys exist and any M of them must sign. A 2-of-3 setup, for example, has three keys and needs any two. The multisignature format was standardised in Bitcoin Improvement Proposal 11 (BIP 11), and the Bitcoin developer documentation describes how wallets use it.
Two points matter. First, the rule is part of the Bitcoin transaction itself, so every node that checks the ledger enforces it. A custodian cannot quietly waive it. Second, signing happens separately: each key holder signs with their own key, and the signatures are combined into the final transaction. No one has to reveal a key to anyone else.
What different setups protect against
- Single key: nothing. Theft or loss of that key decides the outcome.
- M-of-N with M above one: theft of fewer than M keys does not let an attacker spend.
- M below N: loss of up to N minus M keys does not strand the funds, because the remaining keys can still reach the threshold.
What CoinCorner has published about its Vault
The Vault is CoinCorner's optional long-term storage service. According to its Vault page, the keys are held by CoinCorner and by AnchorWatch, across multiple jurisdictions, and the Bitcoin is held in cold storage, which means the keys are kept offline. Those are CoinCorner's own statements, read on 6 October 2026.
CoinCorner does not publish how many keys the Vault uses, how many must sign, or exactly what AnchorWatch's role is in signing. This guide therefore does not describe the Vault as, for example, 2-of-3, because that has not been stated. The custody page and the security page set out what is and is not published, and the about page names the companies behind the service.
Splitting keys between two named parties across jurisdictions is meant to mean that a single failure, whether a compromised system, an insider or a legal action in one country, does not by itself release the Bitcoin. How well that works in practice depends on the threshold and on how each key is stored, which is why you may wish to ask CoinCorner directly.
What a Vault protects against
- A single stolen key. An attacker who obtains one key cannot sign alone, provided the threshold is above one.
- A single lost or damaged key. If the threshold is below the number of keys, the others can still sign. The published pages do not say whether this applies here.
- Remote attacks on online systems. Keys kept offline are not reachable from the internet, which is the point of cold storage.
- Your own device being compromised. You do not hold the Vault keys, so malware on your phone does not hand over a signing key. It may still affect your account login, which is why two-factor authentication matters.
CoinCorner also states that the Vault comes with insurance described as underwritten by Lloyd's of London, covering loss of keys and unauthorised access, subject to policy terms, limits and exclusions. The policy limit and the named insurer are not published, and the terms say cover typically starts on the first day of the calendar month after the transfer. Bitcoin is not covered before then. Read the security page for the detail.
What a Vault does not protect against
- Price falls. Bitcoin's price is volatile and storage does nothing about it.
- Scams you authorise. If you are persuaded to instruct a withdrawal to a fraudster, the keys sign as they should. The FCA publishes warnings on crypto investment scams.
- Custodian risk. You are relying on the key holders to act properly and to stay in business. The published pages do not explain how Vault Bitcoin would be treated if CoinCorner Ltd became insolvent.
- A lack of statutory protection. CoinCorner and investments in cryptoassets are not regulated by the FCA, are not covered by the Financial Ombudsman Service and are not protected by the FSCS. CoinCorner Ltd is registered with the Isle of Man Financial Services Authority as a designated business for anti-money-laundering oversight only, which is not a licence.
- Unpublished evidence. CoinCorner states that customer assets are held 1:1, but no proof-of-reserves report or audit is published, so the claim cannot be checked independently today.
Vault, exchange account or your own wallet
| Option | Who holds the keys | Main trade-off |
|---|---|---|
| CoinCorner Vault | CoinCorner and AnchorWatch | Removes the single key, but you depend on the key holders and on terms that are not fully published. There is a fee, published at 1.50% a year. |
| Exchange account | CoinCorner | Convenient for buying and selling, with one custodian. CoinCorner states that it uses cold storage and multi-signature wallets. |
| Your own wallet | You | No custodian, but loss or theft of your key is your risk alone, unless you set up multi-sig yourself. |
Based on CoinCorner's custody and security pages, read on 19 October 2026. Check the fees page for current charges.
Questions to ask before you use any Vault
- How many keys are there, and how many must sign?
- Who holds each key, in which country, and how is it stored?
- What happens if one key holder is unavailable or ceases to operate?
- When exactly does insurance start, and what are its limits and exclusions?
- How long does a withdrawal take, and does it need extra approval?
- How is the fee charged, and on which balance?
The FAQ covers common account questions, and the support team can answer the rest. A withdrawal is also a normal Bitcoin transaction once signed, so it follows the steps in how Bitcoin transactions are confirmed.
Frequently asked questions
What does multi-signature mean in Bitcoin?
A multi-signature (multi-sig) setup uses several private keys and requires a set number of them to sign before Bitcoin can move. A common pattern is called M-of-N, where M signatures out of N keys are needed. The rule is enforced by the Bitcoin network itself.
Who holds the keys in the CoinCorner Vault?
CoinCorner's Vault page says the keys are held by CoinCorner and by AnchorWatch, across multiple jurisdictions. The number of keys and how many must sign are not published, so ask CoinCorner if you need those details.
If I lose my password, is my Bitcoin in the Vault lost?
Not in the way it would be if you lost the only key to a self-custody wallet, because you do not hold the Vault keys yourself. Access to your account is a separate matter, and CoinCorner's support team and FAQ cover account recovery. Turning on two-factor authentication is advisable.
Does a multi-sig Vault make Bitcoin risk-free?
No. It reduces the risk that one stolen or lost key causes a loss. It does not protect against a fall in the Bitcoin price, a mistaken or scam withdrawal you authorise yourself, or the failure of the firm holding the keys.
Is the Vault covered by the FSCS or the Financial Ombudsman Service?
No. CoinCorner and investments in cryptoassets are not regulated by the FCA, are not covered by the Financial Ombudsman Service and are not protected by the Financial Services Compensation Scheme. The Vault has an insurance policy, but only on its stated terms, limits and exclusions.
Can I withdraw from the Vault whenever I want?
CoinCorner's Vault page says you can withdraw at any time. It does not publish a processing time, and a multi-signature withdrawal needs the required keys to sign, so allow for some delay and confirm the timing with CoinCorner.
Sources
General statements about multi-signature come from the Bitcoin documents below. Statements about the Vault come from CoinCorner's own pages, which were read on 6 and 11 October 2026 and re-checked against this site on 19 October 2026; they are the company's own statements and have not been independently verified. The external documents are cited as the standard references and were not re-read in full when this guide was written, so check each against the original.
- Bitcoin Improvement Proposal 11, M-of-N Standard Transactions: https://github.com/bitcoin/bips/blob/master/bip-0011.mediawiki
- Bitcoin Project, Developer Guides (wallets): https://developer.bitcoin.org/devguide/wallets.html
- Satoshi Nakamoto, Bitcoin: A Peer-to-Peer Electronic Cash System (2008): https://bitcoin.org/bitcoin.pdf
- Financial Conduct Authority, Crypto: The basics: https://www.fca.org.uk/investsmart/crypto-basics
- Financial Conduct Authority, Crypto investment scams: https://www.fca.org.uk/consumers/crypto-investment-scams
- Isle of Man Financial Services Authority, designated business register entry for CoinCorner Ltd: https://www.iomfsa.im/registers/designated-business/?Id=67