Why Multisig?

“Your keys, your bitcoin. Not your keys, not your bitcoin.” – Andreas Antonopolous

This is true, but managing your own keys is really hard. The math behind the bitcoin protocol is bulletproof, but being your own bank requires you to be near perfect in your execution. When it comes to cryptography, you are only as strong as your weakest link. For traditional single-key signature schemes, the only thing between your bitcoin and an attacker is a single mistake! Learn more about some of these risks by listening to SLP Episode 97 with Michael Flaxman.

The central goal of this guide is to help you implement a security scheme with no single points of failure. To accomplish this, you will setup your own multisig wallet using multiple hardware wallets from multiple different vendors. The goal of this guide is to achieve a basic multisig setup: 2-of-3 signatures from different hardware wallets made by different manufacturers.

In order to compromise your multisig setup an attacker must break multiple redundant systems, which, due to the additive power of multisig, is incredibly challenging. Therefore, your level of caution/paranoia/effort (vs a traditional single-key scheme) can be much lower and still achieve much higher security.

If you follow these instructions, you can suffer at least one catastrophic failure and not lose any bitcoin. This could include things like:

• An exploitable software/firmware bug on your hardware wallet
• A pwned (or fake) hardware wallet
• An unscrupulous trusted third party (lawyer/accountant/custodian/etc.) with access to a key for recovery
• A lost/stolen hardware wallet / seed
• An upstream supply-channel attack
• A forgotten PIN / passphrase
• A lost seed
• A compromised random-number generator
• An evil-maid attack
• Malware on your computer
• A rogue bank employee snooping in your safe deposit box
• An eager heir

While this setup is far more secure than a traditional single-key signature scheme (which has little/no fault tolerance), be mindful that the wrong combination of 2+ major mistakes could be enough to lose all of your bitcoin!

Switching to fault-tolerant multisig is the most important thing you can do to improve your security. A lot of people stick with a bad setup – trusted custody or a single-key setup – for fear of change. Don’t let “perfect” be the enemy of “good”; upgrade to multisig today for a solid foundation and continue to learn and iterate over time!

We support users being as paranoid as they want to be, but think that with proper multisig it is overkill for all but the largest HODLers. At each step, there are recommendations for how you can harden your security, and you alone must decide how much time/money you want to spend on hardening your security.

This guide is free, and there are no refunds. There are no bailouts in Bitcoin. We highly recommend you practice all of this first. See disclaimer here.

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