Public key
A public key is a number derived from your private key that is safe to share. The network uses it to verify signatures, and your wallet address is built from it.
How it works
A wallet starts with a private key, a secret number. Elliptic curve math turns it into a public key. It only works one way: knowing the public key, nobody can work out the private key in any realistic time.
When you send coins, your wallet signs the transaction with the private key. Network nodes use the public key to check that the signature is genuine without ever seeing the secret. This is asymmetric cryptography: one key signs, the other verifies.
An address is usually not the public key itself but a shortened hash of it. In Bitcoin and Ethereum this keeps addresses short and adds a layer of protection. Day to day you share an address; the raw public key mostly shows up in software, for example when setting up a multisig.
In Ethereum a public key is 64 bytes. The address is made by taking the Keccak-256 hash of the key and keeping the last 20 bytes. The result is 0x plus 40 hex characters, for example 0x52908400098527886E0F7030069857D2E4169EE7.
A common mix-up is thinking the public key, private key and seed phrase are all just "the wallet key". The public one can be shared; the private key and seed phrase never. If a site or "support agent" asks for your key to verify something, ask which one. A request for a private key or seed phrase always gets a no.
Questions and answers
What is a public key in simple terms?
It is the open half of a key pair. Anyone can use it to check that the owner signed a transaction, but it cannot be used to take your coins.
What is the difference between a public and private key?
The private key signs and gives full control of the funds, so it stays secret. The public key only verifies signatures and is derived from the private key, never the other way around.
Is a public key the same as a wallet address?
Not quite. The address is usually a hash of the public key, which makes it shorter. To receive payments you share the address.
Related terms
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Updated: 2026-10-19