Kerberos

An authentication system developed at the Massachusetts Institute of Technology (MIT). Kerberos is designed to enable two parties to exchange private information across a public network. 

See NIST SP 800-47 for more information. 

A means of verifying the identities of principals on an open network. Kerberos accomplishes this without relying on the authentication, trustworthiness, or physical security of hosts while assuming all packets can be read, modified and inserted at will. Kerberos uses a trust broker model and symmetric cryptography to provide authentication and authorization of users and systems on the network. 

See NIST SP 800-95 (IETF RFC 1501) for more information. 
 
A widely used authentication protocol developed at MIT. In “classic” Kerberos, users share a secret password with a Key Distribution Center (KDC). The user (Alice) who wishes to communicate with another user (Bob) authenticates to the KDC and the KDC furnishes a “ticket” to use to authenticate with Bob.  

See NIST SP 800-63-3 for more information.