Key Distribution Center (KDC) is a central authority dealing with keys for individual computer ( nodes) in a computer network.

• It is similar to the concept of the authentication Services (AS) & Tichel Granting Service (TGS) in Kerheros.
• The basic idea is that every node shares an unique secret key with the KDC. Whenever user wants to communicate securely with user B , the following action take place.

• The background is that A has a secured secret key KA with KDC . Similarly B is assumed to share a secret key KB with the KDC.

• A sends a request to KDC encrypted with KA , which includes:

• Identifies of A & B

• A random number R , called as names.

• KDC responds with a message encrypted with KA , continuing :

a. One - time symmetric key KS.

b. Original request that was sent by A, for verification

c. Plus, KS encrypted with KB & ID of A encrypted with KB.

• A & B can now communicate by using KS for encryption