Public key cryptography is an asymmetric scheme that uses a pair of keys for encryption; a public key, which encrypts data, and a corresponding secret, private key for decryption. You publish your public key to the world while keeping your private key, secret. Anyone with a copy of your public key can then encrypt information that only you can read.

The major benefit of public key cryptography is that the need for sender and receiver to share a secret key is eliminated; all communications involve only public keys. No private key is ever transmitted or shared. Some examples of public-key crypto systems are:

- Elgamal: inventor Taher Elgamal
- RSA: inventors Ron Rivest, Adi Shamir, and Leonard Adleman
- Diffie-Hellman: inventor Diffie-Hellman
- DSA: the Digital Signature Algorithm invented by David Kravitz