Public and private keys, in plain terms
One key proves who you are without ever being shown to anyone. The other is the address people send to.
At a glance
- The private key signs; the public key and address let anyone verify that signature without ever seeing the key itself.
- An address is derived from the public key and can be shared freely — it authorises nothing on its own.
- The maths is one-directional: a public key derives easily from a private one, but not the other way round.
Every crypto address rests on a pair of numbers, generated together and mathematically linked: a private key and a public key. The private key never leaves your device if you're careful with it. The public key, or an address derived from it, is the thing you hand out.
The link between them is one-directional by design. It is computationally trivial to derive a public key from a private one, and computationally infeasible to go the other way. That asymmetry is the entire basis of the system — anyone can verify you signed something without ever learning the key that signed it.
Signing works like this: you take the transaction you want to make, run it through your private key to produce a signature, and broadcast the transaction with the signature attached. Anyone on the network can check the signature against your public key and confirm it could only have been produced by whoever holds the matching private key — without that check ever exposing the key.
An address is typically a shortened, checksummed version of the public key, made safer to read aloud or type. Sharing your address is exactly as safe as sharing a bank account number: it lets people send you money, and authorises nothing else. Sharing your private key is the one action in this entire system that cannot be undone.
| Property | Private key | Public key | Address |
|---|---|---|---|
| Shared with anyone? | Never | Yes, freely | Yes, freely |
| Derived from | Randomly generated | The private key | The public key, shortened |
| Used to | Sign transactions | Verify a signature | Receive funds |
| If exposed | Funds can be moved by anyone | No risk on its own | No risk on its own |
Key terms
- Public key
- The half of the key pair that can be shared; used to verify a signature made by the private key.
- Signature
- Proof, produced by a private key, that a specific transaction was authorised by whoever holds it.
- Address
- A shortened, human-shareable form of a public key that funds can be sent to.
Frequently asked
What happens if two people accidentally generate the same private key?
The keyspace is large enough (roughly 2²⁵⁶ possibilities) that this has never happened and is not expected to by chance in any realistic timeframe.
Is my public key the same as my wallet address?
Usually not exactly — an address is typically a shortened, hashed version of the public key, though the two are directly derived from each other.
Can someone derive my private key from my public key?
Not with current computing methods. The one-way nature of that derivation is the entire security guarantee the system relies on.