Electrumwallet
Electrumwallet multisig
Electrum's multisignature wallets share Bitcoin spending control between cosigners. For a 2-of-2 setup, exchange master public keys and compare receiving addresses before funding the shared wallet.
Updated ยท- Signing requirement
- 2 of 2 in this setup: both cosigners must sign each spend.
- Setup information
- In this software wallet setup, each cosigner creates a separate seed and exchanges master public keys.
- Pre-funding check
- Both wallets must generate the same set of receiving addresses.
- Offline option
- One cosigner wallet can stay offline while the other runs on an online machine.
How the cosigners share control
The master public keys let both wallets construct the shared addresses. Each cosigner keeps their own signing secret, so exchanging public keys doesn't hand over spending authority.
Two people can use this arrangement to require mutual approval for shared funds. One person can also separate the cosigner wallets across online and offline machines.
Prepare both wallets before funding
Electrum's 2-of-2 setup starts with File > New and Multi-signature wallet. Each cosigner selects 2 of 2, creates a separate seed, and enters the other's master public key.
Keep each seed private and safely backed up; the other cosigner only needs your master public key during setup.
You can cancel during the key-exchange stage, then reopen the wallet file when the other cosigner's public key is available.
Hypothetical address check before the first deposit
Both wallets must generate the same receiving addresses before you fund the shared wallet. For this hypothetical session, assume you've configured two unfunded 2-of-2 wallets and exchanged their master public keys.
Compare the receiving addresses in both wallets: matching sets permit funding a shared address, while a mismatch calls for stopping and reviewing the setup.
In this hypothetical session, the address sets match, completing the documented pre-funding check. You leave the wallet unfunded for now; comparing addresses hasn't signed or broadcast a transaction.
Transfer the transaction for the second signature
One cosigner's signature leaves a 2-of-2 transaction partially signed. The other cosigner must add their signature before either wallet can broadcast the completed transaction.
Files and QR codes
Electrum can save the partially signed transaction to a file or display it as a QR code. The second cosigner loads it through Tools > Load transaction > From file or Tools > Load Transaction > From QR Code.
Transferring that data doesn't add the second signature. The receiving cosigner still needs to sign, and broadcasting then submits the completed transaction to Bitcoin. Miners confirm transactions later; broadcast alone doesn't establish confirmation.
Remote exchange with Nostr Cosigner
Electrum 4.6.0 replaced Cosigner Pool with Nostr Cosigner, which exchanges partially signed Bitcoin transactions (PSBTs) over Nostr relays. The former Cosigner Pool method required both wallets to enable the plugin and sent the partially signed transaction through a central server.
In the former Cosigner Pool method, the plugin encrypted the transaction with the recipient cosigner's master public key. The recipient used their wallet password to decrypt it before adding their signature.
Unavailable cosigners and offline signing
A 2-of-2 wallet can't spend with only one available signing key. Keeping one cosigner's seed doesn't replace the other cosigner's signature, so protect both sets of recovery material.
An offline cosigner can sign transaction data transferred from the online wallet. The online machine handles broadcast after both cosigners have signed. Keeping a cosigner offline changes how you transfer transaction data; it doesn't reduce the signature requirement.