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.

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.

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.

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.

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.

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.

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.