Public Key Encryption
A cryptographic system that uses two-keys-a public key known to everyone and a private or secret key known only to the recipient of the message.
An significant element to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them. Furthermore, it is virtually impossible to reduce the private key if you know the public key.