Kerberos

A mature, ticket-based network authentication protocol designed to prove identity over insecure channels using symmetric cryptography.

Developed at MIT under Project Athena in the 1980s, Kerberos serves as the backbone for modern identity management systems like Microsoft Active Directory. It eliminates the need to transmit passwords across the wire by utilizing a Key Distribution Center (KDC) to issue time-stamped tickets. These tickets (TGTs) allow users to access specific services (LDAP, file shares, or databases) without re-authenticating for every session. By relying on a trusted third party and strict time synchronization (usually within 5 minutes), Kerberos effectively mitigates replay attacks and remains the industry standard for secure, single sign-on enterprise environments.

https://web.mit.edu/kerberos/