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.

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.

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 people working in my field also are quite skeptical of our ability to do this. It ultimately boils down to the problem of building complex systems that are reliable and that work, and that problem has long predated the problem of access to encryption keys.

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.

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.

As the local police department might want to decrypt a phone of a criminal suspect, so would the Chinese or the Russian or the Iranian intelligence agencies like to be able to do exactly the same thing.