Not Your Keys, Not Your Coins
The Bitcoin maxim that if someone else holds your private keys, you do not really own the bitcoin - you own a promise from them. Proven, repeatedly, by a decade of custodian failures.
"Not your keys, not your coins" is the most repeated saying in Bitcoin, and one of the most ignored. It means what it says. If someone else controls the private keys to your bitcoin, you don't actually hold bitcoin. You hold a claim against whoever does, and that claim is worth only as much as they are solvent and honest.
The phrase is meant literally, because Bitcoin is a bearer asset. Whoever holds the keys controls the coins, without needing anyone's permission. A balance on an exchange feels exactly like holding bitcoin. You can see the number and log in to check it, right up until the day a withdrawal doesn't go through. That's the moment the difference between owning a coin and holding a claim actually matters.
There's a long record behind the saying. A decade of custodian failures, from Mt. Gox in 2014 to QuadrigaCX in 2018 to FTX and the 2022 lenders, is full of people who found out the hard way that "their" coins were really just an entry in someone else's database. The way out is self-custody: hold the keys yourself, and there's no promise that anyone can break.
See Mt. Gox to FTX: The Custody Graveyard for the receipts behind the maxim.
Key takeaways
- If a third party controls the keys, you hold an IOU, not bitcoin - its value depends on their solvency and honesty
- The phrase is literal: Bitcoin is a bearer asset, so control of the keys is control of the coins
- A decade of collapses, from Mt. Gox to FTX, is the receipts behind the slogan