In computer security, a key server is a computer that receives and then serves existing cryptographic keys to users or other programs. The users' programs can be running on the same network as the key server or on another networked computer.
The keys distributed by the key server are almost always provided as part of a cryptographically protected public key certificates containing not only the key but also 'entity' information about the owner of the key. The certificate is usually in a standard format, such as the OpenPGP public key format, the X.509 certificate format, or the PKCS format. Further, the key is almost always a public key for use with an asymmetric key encryption algorithm.