# Public-Key Cryptography

An encryption system using a mathematically linked public key to encrypt data and a private key to decrypt it.

**Public-key cryptography[↗](/public-key-cryptography)** (also called asymmetric cryptography) is an encryption[↗](/encryption) system built on a mathematically linked pair of keys: a public key that can be shared openly and used to encrypt data or verify a signature, and a private key that must be kept secret and is used to decrypt that data or create a signature. Unlike symmetric encryption[↗](/symmetric-encryption), the two parties never need to exchange a shared secret in advance.

This approach underpins much of modern security, including HTTPS website connections, encrypted email, and digital signatures on software updates. Because the private key never has to travel over the network, public-key cryptography solves the classic problem of securely exchanging a secret with someone you've never met.