Wallets · 27 / 127 · 2 min

Collaborative custody

Two of three keys, and the company holds one. You are not alone, and you are not free of them.

A worked case

A firm says you are protected because they cannot move funds alone. The backup key was generated in their app and stored in their cloud. They hold two. The sentence was true only if the backup was yours.

The threshold

You hold a key. A second key is in another place you chose. The company holds the third. Any two can move the coins.

What that is

Lose your key and the company plus the backup can recover. Lose the company and you plus the backup can leave. The company can also move the coins if they ever hold two keys, or if the backup was never really separate.

Any two

Bitcoin multisignature spends require several keys, not one. A common pitch is two of three: you, a backup, and a company. Any two of those keys are enough.

The pitch is true only while the keys are held by different people. A backup generated inside the company's app, and stored in the company's account, is the company's second key. Then one party can move the coins, and the slogan is still two of three.

Read it yourself

• Multisignature

These links are the record. They are not a recommendation, and they are not instructions. A news story or a court paper can still be wrong about a detail. The check does not change because a famous name is in the story.

Apply the check

Open a question. The line is about this topic. It is not a verdict that anything is safe.

Check yourself

Write it in your own words. The course's answer opens after that. Nothing is sent.