KDC

KDC stands for Key Distribution Center, a central component of the Kerberos network authentication protocol. It acts as a trusted authority that issues tickets used to prove identities and authorize access to services within a realm.

Typically, a KDC provides an Authentication Server (AS) and a Ticket Granting Server (TGS) operating with a shared database of principals and their secret keys. A user authenticates to the AS and receives a Ticket Granting Ticket (TGT) encrypted with the user's key. The TGT allows the user to request service tickets from the TGS without re-entering credentials.

When the user wants to access a service, the client presents the TGT to the TGS to obtain a service ticket for that service. The TGS issues the service ticket, encrypted with the service's key, along with a session key for the client and service. The client then presents the service ticket to the target service, which validates it with its own key and establishes a protected session.

Security and administration: The KDC is a high-value target; compromising it undermines the entire Kerberos domain. Security measures include strong access controls, secure key storage, time synchronization, and redundancy. In large deployments, multiple KDCs and cross-realm trust enable availability and scalability.

Although KDC can refer to other organizations or concepts in different fields, in computer networking it most commonly denotes the Key Distribution Center in Kerberos.