Understanding Public and Private Keys
The cryptography behind crypto ownership, explained without requiring a math background.
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What to remember
- Ownership relies on a linked public/private key pair.
- A public key (or address) can be shared safely; a private key must stay secret.
- The relationship between the two keys works in only one practical direction.
- Sharing your address is safe; sharing your private key or seed phrase is not.
A key pair, not a single key
Crypto ownership relies on a mathematically linked pair of keys: a private key, kept secret, and a public key, which can be shared openly. The public key (or an address derived from it) is where others can send funds; the private key is what authorizes spending them.
Why this design works
The mathematical relationship between the two keys is designed to work in only one practical direction: a public key can be derived from a private key, but the reverse — working out a private key from a public one — is computationally infeasible with current technology. This lets you share your public key freely without exposing your private key.
Signing versus encrypting
- Your private key signs a transaction, cryptographically proving it was authorized by you.
- Anyone can verify that signature using your public key, without ever needing to know your private key.
- This lets the whole network confirm a transaction's authenticity without any party needing to trust a middleman.
A wallet address is not the same as a private key
An address (derived from a public key) is safe to share and is simply where funds can be sent — sharing it does not put your funds at risk. Sharing a private key or seed phrase does.
What to remember
- Ownership relies on a linked public/private key pair.
- A public key (or address) can be shared safely; a private key must stay secret.
- The relationship between the two keys works in only one practical direction.
- Sharing your address is safe; sharing your private key or seed phrase is not.