Which of the following Authentication protocols uses clear text?

The Password Authentication Protocol (PAP) is a basic authentication method used by Point-to-Point Protocol (PPP) to validate users. Its primary characteristic is its simplicity, which unfortunately comes at the cost of security. PAP transmits the username and password across the network in clear, unencrypted text. This lack of encryption makes any network segment where PAP is used vulnerable to eavesdropping attacks, as an attacker with access to the traffic can easily capture the credentials. For this reason, PAP is considered obsolete and insecure for most modern applications.

A. CHAP: Challenge-Handshake Authentication Protocol (CHAP) uses a secure challenge-response mechanism, sending a hash of the password, not the clear text password itself.

C. MSCHAP: Microsoft's version of CHAP (MS-CHAP) also employs a challenge-response system and does not transmit the password in clear text.

D. EAP: Extensible Authentication Protocol (EAP) is an authentication framework, not a specific method. It supports multiple, typically secure, authentication mechanisms and does not inherently use clear text.

1. Fortinet Document Library - FortiOS Administration Guide 7.2.0: In the section on User & Authentication

the guide states: "Password Authentication Protocol (PAP) is a simple authentication protocol. PAP transmits unencrypted ASCII passwords over the network and is therefore considered insecure." (See FortiOS Administration Guide > User & Authentication > Authentication > PAP).

2. RFC 1334 - PPP Authentication Protocols: This is the official standard defining PAP and CHAP.

Section 2.1

"Password Authentication Protocol (PAP)": "The peer sends a password in the clear... This is the most simple-minded of authentication protocols."

Section 3

"Challenge-Handshake Authentication Protocol (CHAP)": "With CHAP

the password is not sent over the link."

3. RFC 3748 - Extensible Authentication Protocol (EAP): This standard defines EAP.

Section 1

"Introduction": "EAP is an authentication framework which supports multiple authentication methods. EAP runs directly over the data link layer without requiring IP." This clarifies that EAP itself is a framework

not a specific clear-text protocol.