Asymmetric encryption, also called public key encryption, uses two different keys. Either key may encrypt or decrypt the message, but one key must be used for encryption only and the other must be used for decryption only. The technique has the highest value when one key is used as a private key and the other is used as a public key. The public key is stored in a public location where anyone can use it. The problem with asymmetric encryption is that it requires four keys to hold a single conversation between two parties. Due to the number of keys involved in asymmetric encryption, it is not as efficient to use as symmetric encryptions in terms of CPU computations and key management.