Today NSA director Keith Alexander told the House Intelligence Committee that the government's surveillance programs have thwarted roughly 50 terrorist plots worldwide, including one directed at the New York Stock Exchange.

But there are still plenty of Americans concerned about the government monitoring their phone calls and emails. 

Which may be why Apple offers this helpful suggestion: Use iMessage. Apple vows the text messaging service is encrypted and can't be read by anyone by the sender and the receiver.

It's the latest attempt by tech giants to assuage a nervous public. National Journal's technology writer Brian Fung has been looking into this and he joins the show with more.