In Robert A Heinlein's The Number of the Beast, computer software expert Deety mentions that if anyone except herself attempts to access her college computer account it would show them her "clean" financial records while secretly deleting the "dirty" copy.
Copied the The Cardinal Of The Kremlin and Dykstra's War examples to Self-Destructing Security.
Moved the The Number of the Beast example to Self-Destructing Security, since it doesn't involve a message.
Edited by Arivne