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A multisig wallet is a crypto wallet that needs more than one key to approve a payment. The common version is 2-of-3: three separate keys exist, and any two of them must sign before coins can move. Lose one key and you can still spend. Have one key stolen and the thief can't spend. And no single person can send the money alone. The price is more setup, more backups to keep straight, and a new kind of mistake: losing too many keys at once.
What is a multisig wallet?
Multisig is short for multi-signature. In an ordinary wallet, one private key signs every transaction, as our guide to public key vs private key explains, and whoever holds it controls the coins. A multisig wallet spreads the power across several keys and sets a rule for how many must agree.
The rule is written as "m-of-n." The Bitcoin developer documentation defines it plainly: m is the minimum number of signatures that must match, and n is the number of public keys in the setup. So 2-of-3 means three keys, two signatures needed. A 3-of-5 means five keys, three needed.
This isn't a new feature. Bitcoin developer Gavin Andresen wrote BIP-11, "M-of-N Standard Transactions," in October 2011. His examples still fit: a 2-of-3 escrow between a buyer, a seller and a referee, and a 2-of-2 where a protection service co-signs with a computer that might be infected. A follow-up proposal in January 2012, BIP-16, let senders pay to a short hashed address without knowing the signing rules behind it. That's why paying into one looks like paying anyone else. According to the developer guide, Bitcoin's standard rules leave room for setups as large as 15-of-15.
On Ethereum and similar networks, a multisig is usually a smart contract that checks approvals before releasing funds. Same idea, different plumbing.
How 2-of-3 multisig works
Picture three keys, each created on a different device and each with its own backup. Together they form one wallet with one set of receiving addresses. When you want to send, your wallet software builds the transaction and asks for signatures. Once any two keys have signed, the network accepts it.
The half-signed transaction travels between devices in a standard format, the "partially signed Bitcoin transaction" set out in BIP-174 in 2017, so offline hardware devices can sign too. In practice that means a file on a memory card or a QR code.
What multisig protects against, and what it doesn't
Multisig solves three specific problems, and only those.
| What happens | Single-key wallet | 2-of-3 multisig |
|---|---|---|
| You lose one key or its backup | Coins are gone if there's no backup | The other two keys can still spend, and move funds to a fresh setup |
| A thief steals one key or seed phrase | The thief can empty the wallet | One key alone can't sign. Move funds before a second key is lost |
| One person wants to act alone | Whoever holds the key decides | A second signer has to agree |
| Two keys are lost or stolen | Not applicable | Lost: coins are locked for good. Stolen: the thief can spend |
| All signers approve a payment they were tricked into | Coins move | Coins move. Multisig checks how many said yes, not why |
That last row matters most. A multisig wallet counts signatures. It can't tell whether the signers understood what they approved.
Real cases: when the threshold or the signing process failed
The most thoroughly documented multisig failures come from crypto companies and bridges, not households. The lessons scale down.
Ronin, March 2022: too few keys in too few hands. The Ronin bridge, built for the game Axie Infinity, needed five of nine validator signatures to approve withdrawals. TechCrunch reported that the attacker obtained five of the nine keys, enough to withdraw tokens to an outside wallet. The developer blamed the small validator set. The FBI said in April 2022 that North Korea's Lazarus Group and APT38 were responsible for the $620 million theft, reported on March 29.
Harmony, June 2022: a low bar. Harmony's Horizon bridge used a multisig that needed only two approvals. CNBC reported in August 2022 that hackers needed to compromise just two of five accounts. The FBI confirmed in January 2023 that the Lazarus Group was behind the $100 million theft.
Bybit, February 2025: the signers were fooled together. The FBI said North Korea stole about $1.5 billion from the exchange on or about Feb. 21, 2025. According to TechCrunch, two outside investigators traced it to a breached developer's computer at the company whose multisig software Bybit used. A malicious file was swapped in that specifically targeted Bybit's Ethereum multisig cold wallet, and the theft happened during what should have been a routine transfer from that cold wallet to a warm one. The required signers were in place. They all worked through the same tampered software.
Ronin and Harmony had keys that were too easy to collect. Bybit had enough signers but no independent way for each to check what they were signing. For a family or a small team, that means keys on different devices, in different places, held by different people, and reading the amount and address on each signing device's own screen.
Common multisig setups for individuals, families and small teams
These are the shapes people use most, with the catch for each. None needs a particular brand of device, and we don't recommend one.
| Who | Typical setup | Why | The catch |
|---|---|---|---|
| One person with long-term savings | 2-of-3, three devices in three locations (home, office, a trusted relative's house or a bank deposit box) | One lost or stolen device isn't a disaster | Three backups to keep current, and travel to reach two keys |
| A couple or family | 2-of-3: one key each for two adults, a third with a trusted relative or lawyer | No one person can move money alone, and the family can still spend if one key is lost | The third keyholder must be trusted and must know what not to do |
| Planning for inheritance | 2-of-3 or 3-of-5 with written instructions kept separate from the keys | Heirs can recover funds without any one person holding everything | Heirs need to understand it. See what happens to crypto when you die |
| A small business or club | 2-of-3 or 3-of-5, one key per officer | Two people approve every payment, and one departure doesn't freeze the account | Keys must change hands when people leave |
| Paid co-signing service | 2-of-3 where the service holds one key | Help with recovery if you lose a key | You rely on that company staying in business and honest |
Whatever the shape, each key gets its own seed phrase, and each seed phrase needs the same care as a single-key wallet's. Our guide on how to store a seed phrase covers paper, metal and where to keep them.
Prefer to watch? How 2-of-3 multisig works, and the scam that asks for one key, in under a minute.
The trade-offs
- More moving parts. Three devices, three seed phrases, and software that ties them together. A setup mistake can stay hidden until the day you need to spend, so test a small spend first.
- Losing too many keys. In a 2-of-3, losing two keys locks the coins forever. Nobody can override it, including the company that made your devices. When one key goes missing, treat it as urgent: use the other two to move everything to a new wallet with new keys.
- The backup most people forget. In a Bitcoin multisig, the seed phrases alone may not be enough to rebuild the wallet. Your software also needs the setup details: which public keys, in what arrangement, under what m-of-n rule. BIP-380, from June 2021, defines "output script descriptors," a standard text format for this. Save the wallet's descriptor or configuration file with each key's backup. It can't spend coins, but it does reveal your balances, so store it as private.
- Higher fees. A multisig spend carries several signatures, so the transaction is larger, and network fees are priced by size. For savings you rarely touch, that's a small cost.
For many beginners, a single hardware wallet with a well-kept backup is the more realistic starting point. Our hot wallet vs cold wallet guide explains that step.
Rob's take
I bought my first Bitcoin in 2011, the same year BIP-11 made multisig a standard transaction. What I like about it isn't the math. It's that it makes you say out loud who you trust and what happens if you're gone. What I'd warn about is the false comfort. Bybit had plenty of signers. They all trusted the same screen.
The scams that use the word "multisig"
Because multisig sounds technical, scammers borrow the word.
- Fake "multisig recovery" helpers. You post that you've lost a key, or that a transaction is stuck, and someone replies offering to recover it. They'll need one of your keys or seed phrases "to rebuild the signature." Combined with the key you already lost, that can be the second key a thief needs. The FBI warned in an August 2025 alert about fake law firms offering crypto recovery, and said no law firms are officially authorized partners of US government agencies.
- "Just one key" requests. A co-signer, a "support agent" or a new online friend says they only need one of your three keys, since one key can't spend anyway. True, until they get a second. Our guide to crypto wallet support scams shows how the fake-support version runs.
- The honeypot wallet. A stranger "accidentally" shares a seed phrase for a wallet that shows a large balance. You import it and find you can't withdraw, because the wallet has been set up so that the scammer's own key must also approve. You send a little crypto to cover fees, and that's what they wanted. It works on the same bait as a honeypot token.
- Fake setup sites. A page offers to "create your multisig" and asks for your existing seed phrases. Real setup happens on your own devices, never by pasting words into a web page.
⚠ Red flag
Anyone who asks for one of your multisig keys, seed phrases or backup files is trying to collect enough of them to spend. A real co-signer in your setup already has their own key and never needs yours. If you've already shared a key, use the remaining keys to move everything to a new wallet now.
Got a message about your wallet and can't tell if it's genuine? Try our is this a scam? quiz, or browse every guide in the Scams hub.
Want the fake-support and fake-recovery messages on one page? Get our free Scam Texts and Emails one-page check when you join the Sunday Briefing.
Multisig wallet FAQ
What does 2-of-3 multisig mean?
It means the wallet has three keys and any two of them must sign before coins can move. You can lose one key and still spend, and a thief with one key can't. If two keys are lost, the funds are locked.
What happens if I lose one key in a 2-of-3 multisig?
You can still spend with the other two. Use them soon to move your funds to a new wallet with fresh keys. Until you do, one more loss locks you out.
Can one person move money out of a multisig wallet alone?
Not if the setup is built properly and each key is held by a different person. That's why businesses and families use it. If one person holds two keys in a 2-of-3, that person can spend alone.
Does a multisig wallet cost more in fees?
Usually a little. Spending from a multisig carries more than one signature, so the transaction is larger, and network fees are priced by size. The difference matters most if you spend often.
Can someone recover my multisig wallet for me?
Only you can, with enough of your own keys and your wallet's setup file. Anyone who offers recovery and asks for one of your keys or seed phrases is trying to steal. The FBI says there are no law firms that are officially authorized partners of US government agencies.
New to all this? Our free course Scam-Proof in 7 Days walks you through the checks one short lesson at a time.