Authentication verifies user information to confirm user identity. Traditional authentication uses a name and a fixed password. This is the most popular, simplest, and least-expensive method of authentication. The disadvantage is that this information can be told to someone else, guessed, or captured. An approach that uses simple, unencrypted usernames and passwords is not considered a strong authentication mechanism, but it can be sufficient for low-authorization or low-privilege levels such as Internet access.
Secure Authentication Using Encrypted Passwords and Cryptographic Techniques
You should use encryption to reduce the risk of password capture on the network. Client and server access control protocols, such as RADIUS, encrypt passwords to prevent them from being captured within a network. However, RADIUS operates only between the authentication, authorization, and accounting (AAA) client and Cisco ISE. Before this point in the authentication process, unauthorized persons can obtain cleartext passwords such as in the following examples:
In the communication between an end-user client that dials up over a phone line.
On an ISDN line that terminates at a network access server.
Over a Telnet session between an end-user client and the hosting device
More-secure methods use cryptographic techniques, such as those used inside the Challenge Authentication Handshake Protocol (CHAP), one-time password (OTP), and advanced EAP-based protocols. Cisco ISE supports a variety of these authentication methods.
Authentication Methods and Authorization Privileges
A fundamental implicit relationship exists between authentication and authorization. The more authorization privileges that are granted to a user, the stronger the authentication should be. Cisco ISE supports this relationship by providing various methods of authentication.