"I think privacy will be to the coming decade what the ecology movement was to the 1970s," he says. But do people who have nothing to hide really need to worry? "With that line of reasoning, why do we need search warrants for the police? Why do we need envelopes for our letters? Why do you need a lawyer present when the police question you? It's damaging to our society to even make that argument. Everyone has something to hide."

Zimmermann acknowledges that limits to encryption should exist—preventing, say, CIA operatives from sending encrypted secrets outside the agency—"but for ordinary people in ordinary jobs, we need more privacy for employees. Often you hear arguments being made that if you write a letter on company equipment, the company should be able to read the letter. But were you to write a letter to your wife, using a company ballpoint pen, would the company have a right to read that letter? Is the ownership of equipment relevant to privacy? I don't think so."