two keys, known as a key pair, are created. You use one key for coding and the other for decoding. The key for coding is generally distributed as a public key. You can place this key on your Web site, for instance. Anyone wishing to send you a message codes it using your public key. When you receive the message, you use your private key to decode it. You are the only one who ever possesses the private key, and therefore it is very secure.