On balance, the use of encryption, just like the use of good locks on doors, has the net effect of preventing a lot more crime than it might assist.

So, in 1993, in what was probably the first salvo of the first Crypto War, there was concern coming from the National Security Agency and the FBI that encryption would soon be incorporated into lots of communications devices, and that that would cause wiretaps to go dark. There was not that much commercial use of encryption at that point. Encryption, particularly for communications traffic, was mostly something done by the government.

The perspective that law enforcement is presenting seems to be a very narrow one that's focused very, very heavily on investigations of past crimes rather than on preventing future crimes. It's very important for policymakers to take that broader view because they're the ones who are trusted to look at the big picture.

Clipper took a relatively simple problem, encryption between two phones, and turned it into a much more complex problem, encryption between two phones but that can be decrypted by the government under certain conditions and, by making the problem that complicated, that made it very easy for subtle flaws to slip by unnoticed. I think it demonstrated that this problem is not just a tough public policy problem, but it's also a tough technical problem.

What encryption lets us do is say, "Yes, the Internet is insecure." Bad guys are able to compromise computers everywhere, but we're able to tolerate that because if they do intercept our messages, they can't do any harm with it.

Telephone handsets are particularly in need of built-in security. We have almost every aspect of our personal and work lives reflected on them and we lose them all the time. We leave them in taxis. We leave them on airplanes. The consequences of one of these devices falling into the wrong hands are very, very serious.

Computer science doesn't know how to build complex systems that work reliably. This has been a well-understood problem since the very beginning of programmable computers.