Explanation:
Remote Authentication Dial-In User Service (RADIUS) is a networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service.
With RADIUS only the password is encrypted while the other information such as username, accounting information, etc are not encrypted. Encryption is “the process of converting information or data into a code, especially to prevent unauthorized access”. So since RADIUS only encrypts the passwords, there is no confidentiality.