Comment sauvegarder les phrases de récupération d'un portefeuille multisig
Comment sauvegarder les phrases de récupération d'un portefeuille multisig
How to back up a multisig wallet’s seed phrases comes down to one rule: back up every cosigner’s seed phrase separately, in its own location, and back up the wallet configuration alongside them. In a common 2-of-3 setup, any two seeds can help rebuild access, but the seeds alone are not the whole backup. Without the wallet configuration, recovery can fail even when you still hold enough words.
How to back up a multisig wallet’s seed phrases
Start by listing what your wallet actually consists of. A multisig wallet is not one wallet with one phrase. It is a shared wallet built from two or more separate signing keys, and each key normally has its own seed phrase, often 12 or 24 words. A 12-word BIP39 phrase has 128 bits of entropy, and each phrase in your setup protects one signing key only.
Your backup therefore has two parts. The first part is the set of seed phrases, one for each cosigner or signing device. The second part is the wallet configuration: the threshold (for example 2-of-3), the extended public keys or fingerprints of every cosigner, the address type, and the derivation information recorded when the wallet was created. Many wallets call this the wallet descriptor or multisig configuration file. Lose it and you may hold the right words yet still be unable to rebuild the same wallet.
Write both parts down before you send any meaningful amount of bitcoin to the wallet. The guide hub at Guides « Ne perdez jamais vos bitcoins » covers the wider backup routine this process fits into.
Back up each seed phrase on its own
Treat each seed phrase as a complete, independent backup. Write the words by hand, in order, numbered, and check every word against the signing device screen before you store it. Do not type the words into a phone, a computer document, or a cloud note to make the process faster. A multisig setup improves security only if each key stays private on its own.
Label each backup clearly, but carefully. A good label names the wallet and the cosigner slot, for example Wallet A, Key 1 of 3, plus the master fingerprint shown by your wallet software. That helps you match a phrase to the right key years later. Never write the wallet balance or the locations of the other backups on any single backup.
For a long term backup, stamp or etch each phrase on metal rather than relying on paper alone, for the same reason covered in Comment tester la sauvegarde de votre phrase de récupération sans mettre vos fonds en danger: a backup you have never checked is a hope, not a backup. Keep each phrase on its own plate or sheet. Never combine two phrases on one piece of paper or one metal plate to save space, because that single item then defeats the separation multisig was built to give you.
Store the backups in separate locations
Separation is the point of multisig, so store each seed phrase in a different place. In a 2-of-3 wallet, no single location should hold two phrases, because a burglar, a fire, or a flood at that one spot would then either destroy your safety margin or hand someone enough keys to meet the signing threshold on their own.
A workable pattern is simple. Keep one phrase at home in a locked, fire resistant place. Keep the second in a separate property, a trusted family home, or a safe deposit arrangement you control. Keep the third with another cosigner, or in a second off site location. One event, at one address, should never expose or destroy two keys.
Store a copy of the wallet configuration in more than one of those locations, plus one extra copy you can reach easily, such as an encrypted file you control. The configuration contains public information, not private keys, so it cannot spend funds by itself. It still deserves care, because it reveals that a multisig wallet exists and shows its public keys.
Do not forget passphrases and cosigners
If any signing key uses a passphrase, sometimes called the 25th word, that passphrase is part of that key’s backup. A seed phrase without its passphrase restores a different wallet. Back up each passphrase separately from the phrase it belongs to, so one find does not hand over the complete key, and record which passphrase pairs with which cosigner slot. The background in what is a passphrase and should you use one explains why this extra word changes recovery.
If other people are cosigners, agree the backup standard before the wallet holds funds. Each cosigner backs up their own phrase and keeps a copy of the wallet configuration, and nobody should hold a copy of anyone else’s phrase for convenience. Agree also what happens if a cosigner loses a key or becomes unreachable. Multisig can survive one lost key in a 2-of-3 setup, but only if you act while the remaining keys are still available.
Do not confuse multisig with splitting one phrase into pieces. Multisig uses several complete keys. That differs from a scheme such as the one explained in what is Shamir secret sharing for seed phrases, where shares of a single secret are distributed instead. Write down plainly which system your wallet uses.
Test the recovery before you trust it
Test recovery while the wallet holds only a small test amount. Use a fresh device or a clean wallet install, restore from the backups you actually stored, and confirm you can rebuild the same wallet, see the same addresses, and sign a transaction with the required number of keys. In a 2-of-3 wallet, test that any working pair can sign, and confirm what happens when only one key is available: you should be able to view the wallet with the configuration, but not spend.
Write down the steps that worked, in plain language, and store those instructions with the wallet configuration. Include the wallet software name and version, the address type, and where each backup lives, without printing the seed words in the instructions. Then check the backups yearly. A short check that each backup is still present, legible, and in its recorded place costs little and catches most quiet failures.
Common mistakes to avoid
The most common mistake is backing up the words and nothing else. The second is the opposite shortcut: keeping all the phrases together in one drawer, one safe, or one encrypted folder, which turns a multisig wallet into a single point of failure with extra steps. Other frequent errors include photographing a phrase during setup, sending a configuration file and a seed phrase in the same message, and funding the wallet heavily before a single recovery test.
Avoid clever hiding tricks that nobody could follow in an emergency. Your plan has to work for a tired, stressed version of you, possibly years from now. Simple, labelled, separated, and tested beats ingenious every time.
Réponses rapides
Do I need to back up every seed phrase in a multisig wallet? Yes. Each cosigner key has its own phrase, and each phrase needs its own separate backup. Losing more phrases than your threshold allows can lock the wallet for good.
Are the seed phrases enough on their own? Not reliably. You also need the wallet configuration, including the threshold, every cosigner’s extended public key or fingerprint, and the address type. Back up that configuration in more than one place.
Can I store two seed phrases in the same safe to keep things simple? No. In a 2-of-3 wallet, two phrases in one place let one theft or one disaster decide the fate of the wallet. Keep each phrase in a separate location.
Should a cosigner keep a copy of my seed phrase as a spare? No. Each cosigner backs up only their own phrase. Holding someone else’s phrase breaks the separation that makes multisig safer than a single key wallet.
What if I lose one seed phrase from a 2-of-3 wallet? Act promptly. With two keys still available, you can move the bitcoin to a fresh multisig wallet with new keys and new backups. Do not wait until a second key is lost.
