Designing an authentication system

Not code, but a design. Two developers argue their way to Kerberos one objection at a time: every scene opens with a hole in the previous scene’s scheme and closes with the fix. By the end you know not just how tickets and authenticators work but why each piece has to be there.

Dramatis Personae

Athena an up and coming system developer.
Euripides a seasoned developer and resident crank.

Scene I

A cubicle area. Athena and Euripides are working at neighboring terminals.

Athena: Hey Rip, this timesharing system is a drag. I can’t get any work done because everyone else is logged in.

Euripides: Don’t complain to me. I only work here.

Source: Designing an Authentication System: a Dialogue in Four Scenes by Bill Bryant, February 1988; cleaned up and extended with an afterword by Theodore Ts’o, 1997.