Public Key Cryptography

A coding system in which encryption and decryption are done with public and private keys, allowing users who dont know each other to send secure or verifiable messages. Suppose Fred wants to send a message. He would encrypt it with his private key, which no one else knows; then, the recipient would decrypt it using Freds publicly available key, thus verifying that the message came from Fred. Alternately, suppose Fred wants to receive an encrypted message. The sender would encrypt the message with Freds public key, and only Fred would be able to decrypt it, using his private key. This method, also known as dual-key cryptography, contrasts with the older secret-key or symmetric cryptography, in which the sender and recipient must agree on and use the same private key for encryption and decryption.