Public Key

A public key is the shareable half of a cryptographic key pair, derived mathematically from your private key and used to verify that transactions were genuinely signed by the key's owner. In cryptocurrency, your addresses are generated from your public key, and when you spend funds, the network checks your transaction's digital signature against the public key to confirm authorization — all without your private key ever being exposed.

The system rests on one-way math: computing the public key from the private key is easy, but reversing the process is computationally infeasible. This is what makes it safe to share public keys and addresses openly. For example, when you send bitcoin, your wallet signs the transaction with your private key and reveals the corresponding public key; every node on the network can then verify the signature matches, proving the rightful owner approved the spend, while learning nothing that would let them forge future transactions.

A common misconception is that a public key and an address are the same thing; an address is usually a shortened, hashed version of the public key, which adds a small extra layer of security and makes the identifier more compact. In everyday use you share addresses rather than raw public keys, and your wallet handles the key mathematics invisibly. The same public-key cryptography that secures crypto also underpins much of the internet, including the encryption behind secure websites.