Crypto glossary

Public Key

A public key is the shareable half of a wallet's key pair. It is calculated from the private key, is used to verify your signatures, and is the basis from which your receiving addresses are derived.

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How the key pair works

A crypto wallet starts with a private key, a very large secret number. Using elliptic-curve cryptography, the wallet computes a public key from it. This calculation only works in one direction: getting the public key from the private key is easy, but working backwards is practically impossible with today's computers.

When you send coins, your wallet signs the transaction with the private key. Anyone on the network can then check that signature against the public key and confirm that the owner approved it, without ever seeing the private key.

Public key versus address

The address you share to receive coins is usually not the raw public key but a shorter version derived from it. Bitcoin hashes the public key and adds a checksum; Ethereum takes the last 20 bytes of a hash of the public key, which is why its addresses start with 0x and are 40 hexadecimal characters long. Hashing makes addresses shorter and harder to mistype.

Modern wallets also use extended public keys, often called xpubs, from which a whole series of addresses can be generated. This lets a wallet show a fresh address for every payment.

Is it safe to share?

Sharing a public key or an address cannot let anyone move your funds. It does affect privacy, though: anyone with an address can see its full history and balance on the blockchain. An extended public key is even more revealing, because it exposes every address in that wallet. Treat an xpub as private information and give it only to software you trust, such as a portfolio tracker you control.

Common confusions

The public key is not a password and not a recovery tool; losing it does not matter as long as you have the private key or seed phrase, from which it can be recalculated. Mixing up the two is dangerous in one direction only: never enter a private key or seed phrase where a public key or address is requested.

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Frequently asked questions

Can someone steal my crypto with my public key?

No. Moving funds requires a signature made with the private key, which cannot practically be derived from the public key.

Is my wallet address the same as my public key?

Usually not exactly. The address is derived from the public key, typically by hashing it, which makes it shorter and adds error checking.

What is an xpub?

An extended public key that can generate all receiving addresses of a wallet. It cannot spend funds, but it reveals the wallet's entire history.

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All glossary terms · Educational reference only — not investment, legal, tax or financial advice.