All that said, email isn't the only way to communicate. Silent Circle, a National Harbor, Md.–based company, offers encrypted phone calls, texts and even a Skype-like video call service. Silent Circle also used to offer an encrypted email service but discontinued it.
Silent Circle offers a subscription service geared to mobile devices such as smartphones. The encryption keys are a "one-time pad"—used and then discarded. When a user fires up Silent Circle on her phone, the software links to a private network, a secure tunnel to a server in Canada or Switzerland. Once the message (or phone call) arrives there, it is routed to the ordinary public network to complete its journey. The encryption happens on the device itself. So anyone who tries eavesdropping on the call won't be able to pick up the key. For example, if the Chinese government wanted to listen to a Silent Circle user's call, they won't be able to do it unless they had some way of accessing the call in the U.S.
Speaking of which, if the recipient is a Silent Circle subscriber and in the U.S., the NSA wont be able to listen to that end of the conversation, either. Silent Circle also offers secure calls in the other direction, using a normal 10-digit phone number that links up to Silent Circle's server.
Silent Circle's selling point is that the cryptography is distributed. Not even Silent Circle can read the messages sent over its network, as they aren't stored.
Other phone encryption programs include Open Whispersystems, which offers an app called RedPhone that encrypts texts and calls on Android devices (the company says it's working on an iPhone version).
With all these products out there, it's important to emphasize that good encryption depends on the snooper not being able to crack the code in a reasonable amount of time. The NSA reportedly stores encrypted messages for five years on the assumption that eventually the computing power will be there. So the people designing code schemes have to stay ahead—Silent Circle, for instance, is moving to more advanced mathematical techniques to do just that, according to Spencer Snedecor, chief revenue officer.
Of course, there's always hoping that the eavesdroppers don't know your language. "Learn Klingon. It defeats all but the most hard core of sci-fi stalkers," Wisniewski said.
—By Jesse Emspak, Special to CNBC.com