Public key vs. private key
One you can share with anyone. One you must never share with anyone.
Your private key is a secret number that lets you spend your crypto; never share it. Your public key is calculated from it and lets anyone check your signatures. Your address is a shorter code made from the public key, and it's what you give people to receive crypto.
Side by side
| Compare | Private key | Public key / address |
|---|---|---|
| What it does | Signs transactions: proves you can spend | Receives funds and lets others verify your signatures |
| Share it? | Never | Yes, the address is meant to be shared |
| If someone else gets it | They can take all the funds | They can see the balance and history, but can't spend |
| Looks like | A 64-character code, usually hidden by your wallet | Bitcoin address: bc1q… · Ethereum address: 0x… |
How a signature works, simply
Think of a wax seal that only you can make, but anyone can check. Your wallet uses your private key to seal a transaction. The network uses your public key to confirm the seal is genuine and that the transaction wasn't changed. The private key itself is never sent.
The math only works one way: it's easy to get the public key from the private key, but practically impossible to go backwards, even with every computer on Earth working on it.
The technical version
Bitcoin and Ethereum use elliptic-curve cryptography on the secp256k1 curve. A private key is a 256-bit number. Multiplying a fixed point on the curve by that number gives the public key; reversing the multiplication is the elliptic-curve discrete logarithm problem, believed infeasible. Addresses are hashes of the public key (Ethereum: the last 20 bytes of its Keccak-256 hash), which makes them shorter and adds a checksum.
Your seed phrase can regenerate all your private keys, so treat it exactly like a private key: never share it, type it into a website or photograph it.
Frequently asked questions
Is my wallet address public?
Yes. It's designed to be shared, and anyone can look up its balance and history on a block explorer. Some people use a new address for each payment for privacy.
Can someone steal crypto with my address?
No. Your address only lets people send to you. Spending needs the private key.
Where is my private key?
Your wallet stores it (encrypted) and usually never shows it. It can be recreated from your seed phrase.
Where to next
Sources
Written for beginners and checked against the sources listed. Last reviewed October 26, 2026. This page is educational and is not financial, tax or legal advice. How we write and check pages.