What protocol utilizes symmetric key cryptography for secure authentication?

Kerberos is a network authentication protocol that utilizes symmetric key cryptography to ensure secure authentication. In Kerberos, when a client wants to access a server, it first authenticates itself to a trusted third-party service known as the Key Distribution Center (KDC). The KDC issues a ticket that allows the client to access the server without needing to send its password over the network.

The use of symmetric key cryptography means that both the client and the server share a common secret key that is used for encrypting and decrypting messages. This process ensures that the authentication process can remain secure even over potentially insecure networks, as the shared key is never transmitted but is rather used to encrypt communication.

In contrast, while SSH (Secure Shell) does use symmetric key cryptography for data transmission after authentication, it primarily relies on public key cryptography for the initial authentication phase. LDAP (Lightweight Directory Access Protocol) is typically used for directory services and may utilize various authentication methods, but it is not specifically a protocol focused solely on symmetric key cryptography for authentication. VPN (Virtual Private Network) protocols may also employ symmetric key encryption for securing data transmission, but they are generally not dedicated to authentication alone. Therefore, Kerberos stands out in this context as the