Which LDAP authentication mode can provide secure authentication?

SASL, or Simple Authentication and Security Layer, is the correct choice for providing secure authentication in LDAP. It enables a variety of authentication mechanisms, including those that support encryption and integrity protection, such as Kerberos or OAuth. By utilizing SASL, organizations can implement more robust security measures when authenticating users against directory services.

One of the notable features of SASL is its flexibility, allowing it to work with various authentication mechanisms that can ensure not only the identity of the user but also protect the information transmitted during the authentication process. This ensures that sensitive credentials are not easily intercepted during transmission.

In contrast, SSL provides encryption for data in transit but is more of a transport layer security method rather than an authentication method per se. While it enhances the overall secure communication, it does not directly dictate the authentication mechanism itself like SASL does.

Plaintext and Simple authentication methods do not provide any form of encryption and are therefore vulnerable to interception and replay attacks, making them unsuitable for secure authentication. They send credentials in an unprotected format over the network, which can lead to security breaches.