At a remarkable conference held at the Aspen Institute in 2011, Gen. Michael Hayden, a former head of both the National Security Agency and the Central Intelligence Agency, said something very interesting. In a discussion of how to secure the "critical infrastructure" of the United States, he described the phenomenon of compromised computer hardware — namely, chips that have hidden "back doors" inserted into them at the design or manufacturing stage — as "the problem from hell." And, he went on, "frankly, it's not a problem that can be solved."