Private key

The cryptographic secret that authorises spending Bitcoin. If someone gets your private key, they can spend your sats.

A private key is the secret number that authorises Bitcoin transactions. Possession of the private key is possession of the Bitcoin — there is no other layer of authentication. If your private key is compromised, your sats can be spent by whoever has it.

Private keys are stored inside wallets. They're typically derived from a seed phrase using BIP-32 (so a single 12-word phrase can generate millions of private keys for different addresses). You never see the raw private key in normal wallet usage; the wallet handles it for you.

The cardinal rule: never share your private key, never type it into any website, never enter it into a "recovery" tool. Same for your seed phrase — it's the master version of all your private keys.

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Related terms

Glossary

Public key

The cryptographic counterpart to a private key. Used to derive addresses and verify signatures. Safe to share.

Glossary

Seed phrase

A 12 or 24-word phrase that backs up your entire wallet. Lose it, lose your sats. Share it, lose your sats.

Glossary

Self-custody

Holding your own Bitcoin private keys. Nobody can freeze, seize, or lose your sats — except you.

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