Definition
Kerberos is a network authentication protocol that uses secret key cryptography to provide strong authentication for client server applications. It operates on the principle of a trusted third party, the Key Distribution Center (KDC), which issues temporary tickets to users and services. When a user wants to access a resource, they present a ticket-granting ticket to the KDC to obtain a service ticket for that specific resource. This process ensures that only authenticated users can access protected network resources, preventing unauthorized access and man-in-the-middle attacks. For instance, logging into a Windows domain often utilizes Kerberos for authenticating your computer and user account to the domain controller. It is distinct from simple password-based authentication, which typically sends credentials in plaintext or with weaker encryption. Kerberos is a key topic on the CompTIA Security+ and CISSP exams.