Kerberos

The original story…

Kerberos (aka Ceberus, Cerberos) is the three headed dog in Greek and Roman mythology who guarded the gates of Hades, which is where most people spend the afterlife, if they haven’t been immortalized or turned into constellations or rocks, flowers, animals, birds, etc. This pup of Hades lets people into Hades, but devours them if they try to leave. (That way, no one comes back from the dead, but in mythology there’s always exceptions.) The final labor of Herakles (Hercules to the Romans) was to bring Kerberos to the world of the living. Herakles prepared well and succeeded. He subdued Kerberos by force, but returned the dog to Hades once he completed the task.

The modern usage…

Kerberos today is a network security protocol originally developed by MIT for use in their Athena system. (That’s why they have a 3 headed dog as its logo.) It authenticates users and encrypts their communication with strong cryptography. It’s now used widely by many systems. For example, users wishing to connect to an otherwise unsecured wireless network may first have to go through Kerberos. A system may also distribute “tickets” for using other applications through Kerberos’ authentication scheme.