key distribution center

A type of key center (used in symmetric cryptography) that implements a key-distribution protocol to provide keys (usually, session keys) to two (or more) entities that wish to communicate securely. (Compare: key translation center.)

"COMSEC facility generating and distributing key in electrical form." [C4009]

Tutorial: A KDC distributes keys to Alice and Bob, who (a) wish to communicate with each other but do not currently share keys, (b) each share a KEK with the KDC, and (c) may not be able to generate or acquire keys by themselves. Alice requests the keys from the KDC. The KDC generates or acquires the keys and makes two identical sets. The KDC encrypts one set in the KEK it shares with Alice, and sends that encrypted set to Alice. The KDC encrypts the second set in the KEK it shares with Bob, and either (a) sends that encrypted set to Alice for her to forward to Bob or (b) sends it directly to Bob (although the latter option is not supported in the ANSI standard [A9017]).