This addresses the wrong question. As soon as you start using encryption, you also start using passwords and secret keys. The US government can detect encrypt

This addresses the wrong question. As soon as you start using encryption, you also start using passwords and secret keys. The US government can detect encrypted messages and find those passwords and keys pretty easily. Better to send scattered, seemingly innocuous plaintext messages, if the insidious information is coded well enough to look like normal conversation. If you encrypt all your email, they just have to log every piece of encrypted mail they see and wait until they find the key to open all of them. If you do it the smart way, they have to hunt for each individual message, and you win the "security arms race".