Public-key cryptography works with a matched pair: a private key, which must be kept secret, and a public key, which is derived from it and safe to share. In crypto wallets, the public key is used to generate the wallet address that other people send funds to, while the private key is what actually authorises spending from that address. This pairing is what makes it possible to receive crypto from strangers safely, since sharing an address derived from a public key reveals nothing about the private key needed to spend from it.
The relationship between the two keys is deliberately one-directional. The public key can be freely calculated from the private key, but the private key cannot practically be worked out from the public key alone. This allows a public key, or an address derived from it, to be shared with anyone without exposing the private key that controls the funds. That one-way relationship relies on mathematical problems that are computationally impractical to reverse with current technology, which underpins the security of the whole system.
Public keys also let anyone verify that a transaction was genuinely signed by the holder of the matching private key, without that private key ever being revealed or transmitted. This is the basic mechanism that lets a blockchain confirm a transaction is authorised, while still keeping the actual private key completely secret.
Key takeaways
- A public key is derived from a private key and can be shared safely, unlike the private key itself.
- Public keys are used to generate the wallet addresses that other people send funds to.
- Public keys allow anyone to verify a signed transaction without ever needing to see the private key.
Public Key — frequently asked questions
Is a public key the same thing as a wallet address?
They are closely related but not always identical. A wallet address is typically a shortened, encoded form derived from the public key, often including extra characters used to help catch typing errors.
Can someone steal funds if they know a public key?
No. A public key alone cannot be used to spend funds or to work out the corresponding private key. It is specifically designed so that wallet addresses derived from it can be shared freely and published openly without putting any funds at risk.
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