Crypto AG was a CIA front. That's a real thing that happened. How can we be sure no one is using the tech without using the tech? (And, once someone somewher

Crypto AG was a CIA front. That's a real thing that happened. How can we be sure no one is using the tech without using the tech? (And, once someone somewhere is using the tech, why not solve all crime? Why have the illusion of privacy, and permit e.g. kidnapping, rape, murder?)