Which one is NOT a type of passive authentication?

In the context of authentication types, passive authentication refers to methods that do not require active user interaction for identity verification.

FSSO (Fortinet Single Sign-On) and RSSO (Remote Single Sign-On) are both systems designed to enable users to automatically authenticate without needing to repeatedly enter credentials during their session. They operate by monitoring user activity or leveraging existing authentication mechanisms in a more passive manner.

NTLM (NT LAN Manager) is another authentication protocol that operates without needing constant user input, providing authentication based on cached credentials and existing session information.

Conversely, CHAP (Challenge Handshake Authentication Protocol) is an active authentication method. It involves a challenge-response mechanism where the server sends a challenge to the client, which must then compute a response based on its credentials and return it to the server for verification. This interaction requires both parties to communicate after the initial session setup, making it an active process rather than passive.

Thus, identifying CHAP as the type that is not passive highlights the key characteristic that it requires active involvement in the authentication process, distinguishing it from the other methods listed.