"Computer security is a test of an engineer’s ability to nail down every single path the computer could take, in the face of adversaries who can search all possible ways to perturb the system. It is a famously losing battle – even though the engineers can fully control and craft their own computer’s code. We dub this central challenge the curse of edge cases: To be secure, a computer system must work in the face of cases that are outside of the normal and expected range, cases that occur on the edges of possibility."