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.

It may be true that encryption makes certain investigations of crime more difficult. It can close down certain investigative techniques or make it harder to get access to certain kinds of electronic evidence. But it also prevents crime by making our computers, our infrastructure, our medical records, our financial records, more robust against criminals. It prevents crime.

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.

The security of computers and the Internet is a horrible and dangerous mess. Every week we hear about breaches of databases of Social Security numbers and financial information and health records, and about critical infrastructure being insecure.

From a policymaker's point of view, [the back door] must look like a perfect solution. "We'll hold onto a separate copy of the keys, and we'll try to keep them really, really safe so that only in an emergency and if it's authorized by a court will we bring out those keys and use them." And, from a policy point of view, when you describe it that way, who could be against that?

There's been a certain amount of opportunism in the wake of the Paris attacks in 2015, when there was almost a reflexive assumption that, "Oh, if only we didn't have strong encryption out there, these attacks could have been prevented." But, as more evidence has come out - and we don't know all the facts yet - we're seeing very little to support the idea that the Paris attackers were making any kind of use of encryption.

If we try to prohibit encryption or discourage it or make it more difficult to use, we're going to suffer the consequences that will be far reaching and very difficult to reverse, and we seem to have realized that in the wake of the September 11th attacks. To the extent there is any reason to be hopeful, perhaps that's where we'll end up here.