ERA User Guide

Bitcoin multisig

Bitcoin multisig on ERA

You will haveYou will know what a multisig wallet is, which part ERA plays in it, and which guide to read next.
Time2 min
You needNothing extra

This page is background for the four multisig how-to guides. If you already know what a 2-of-3 wallet is, skip to Export your cosigner key.

What a multisig wallet is

A multisig wallet (a Bitcoin wallet shared by several keys) needs more than one signature to spend. In a 2-of-3 wallet three keys are enrolled and any two of them must sign a transaction, so one lost or stolen key cannot move your bitcoin.

What ERA does in a multisig wallet

ERA holds one of the keys, called a cosigner (one key holder in a multisig). It does three things:

  • Exports its XPUB (the public half of its key) as a QR code, so the coordinator app can enrol ERA as a cosigner. See Export your cosigner key.

  • Imports the wallet descriptor (the file that lists every cosigner and the signing rule) and keeps it on the device, so ERA can recognise the wallet later and check that change comes back to it. See Import a multisig descriptor and View or delete a saved descriptor.

  • Signs PSBTs (unsigned Bitcoin transactions) that the coordinator sends as a QR code, and shows its signature as a QR code for the coordinator to collect. See Sign a multisig transaction.

The other cosigners can be other hardware wallets, phones, or a second ERA. The coordinator app collects the signatures and broadcasts the transaction; ERA never connects to the internet.

Which coordinator apps work with ERA

ERA speaks the two formats that Bitcoin multisig coordinators share:

DirectionFormatCoordinators
ERA → coordinatorcosigner XPUB as a crypto-account QR codeSparrow, Nunchuk, BlueWallet
Coordinator → ERAwallet descriptor as a Coldcard-style multisig text file, shown as a QR code (or an animated QR code)Sparrow, Nunchuk, BlueWallet

ERA exports keys for Native SegWit (P2WSH, the default in modern coordinators) and Nested SegWit (P2WSH-P2SH) multisig wallets. A descriptor in any other format (for example legacy P2SH) is rejected on import.

Order of the guides

  1. Export your cosigner key — once per wallet, on every ERA cosigner.

  2. Import a multisig descriptor — once per wallet, after the coordinator has all keys.

  3. Sign a multisig transaction — every time you spend.

  4. View or delete a saved descriptor — when you need to check or remove a wallet.