⚠️ This series was written long before COLDCARD's catastrophic seed generation bug was exploited in 2026. It uses a COLDCARD as one of the three signers. Do not use COLDCARD, here or anywhere else. A firmware bug that went unnoticed from 2021 until July 2026 made seeds generated on COLDCARD devices weak enough to guess, and attackers used it to steal more than 1,800 BTC (Coinkite's advisory, more detail). Use Passport Prime in its place, and where this series shows COLDCARD steps, follow the Passport Prime documentation instead.
If one of your multisig signers was created on a COLDCARD, treat that key as compromised. Your funds are then only as safe as your other keys, so set up a new multisig with a replacement signer and move your funds to it.
Disclosure: I work at Foundation, the company that makes Passport Prime.
Welcome
Welcome to the Bitcoin Multisig Guide! Before you read any further, we want to make clear that this site is for intermediate/advanced users of Bitcoin only. In the right hands, multisignature wallet setups offer protection against a wider range of attack vectors when compared with single signature setups. In the wrong hands, multisignature wallets can result in an irrecoverable loss of funds.
Your Bitcoin security strategy should be selected with caution. In 95% of cases, the simplest option is probably the right one.
Let’s get started!
Table of Contents
- Intro
- Shopping list
- Software preparation
- Signer setup
- Wallet setup
- Wallet backup
- Receiving bitcoin
- Spending bitcoin
- Practice recovery
If after reading this guide you want to try multisig for yourself but think you’d benefit from a more personalised tuition approach, I offer private support calls.