Derek Atkins wrote:

This is a joke, right?

Gee, either that or the Towers of Hanoi. O.K., quick now off the top of my head. Make a key. Make an ultimately trusted key for each of your employees. Have employees make their key. Sign each of the employees keys with your ultimately trusted key for employee. Fire all of your employees. Worry about someone thinking that said employee is still an employee, revoke ultimately trusted key for employee. Yes, a key management problem, but maybe someone could write some code . . . (You know, I much prefer multiple guess.)