There are several different types of combinations of authentication. Higher levels of security are generally associated with more levels of authentication (multifactor). For example, two-factor authentication might include a token and a password. Kerberos is a protocol for authentication made up of two components: a ticket (distributed by a service) for user authentication and a key that is developed from the user’s password. Another authentication scheme is the Challenge-Handshake Authentication Protocol (CHAP), which uses a representation (hash) of the user’s password to authenticate.