The thing about infrastructure is that everyone uses it. If it's secure, it's secure for everyone. And if it's insecure, it's insecure for everyone. This forces some hard policy choices.
When I was working with the Guardian on the Snowden documents, the one top-secret program the NSA desperately did not want us to expose was QUANTUM. This is the NSA's program for what is called packet injection—basically, a technology that allows the agency to hack into computers.
Turns out, though, that the NSA was not alone in its use of this technology. The Chinese government uses packet injection to attack computers. The cyberweapons manufacturer Hacking Team sells packet injection technology to any government willing to pay for it. Criminals use it. And there are hacker tools that give the capability to individuals as well.
All of these existed before I wrote about QUANTUM. By using its knowledge to attack others rather than to build up the internet's defenses, the NSA has worked to ensure that anyone can use packet injection to hack into computers.
Technological capabilities cannot distinguish based on morality, nationality, or legality
This isn't the only example of once-top-secret US government attack capabilities being used against US government interests. StingRay is a particular brand of IMSI catcher, and is used to intercept cell phone calls and metadata. This technology was once the FBI's secret, but not anymore. There are dozens of these devices scattered around Washington, DC, as well as the rest of the country, run by who-knows-what government or organization. By accepting the vulnerabilities in these devices so the FBI can use them to solve crimes, we necessarily allow foreign governments and criminals to use them against us.
Similarly, vulnerabilities in phone switches—SS7 switches, for those who like jargon—have been long used by the NSA to locate cell phones. This same technology is sold by the US company Verint and the UK company Cobham to third-world governments, and hackers have demonstrated the same capabilities at conferences. An eavesdropping capability that was built into phone switches to enable lawful intercepts was used by still-unidentified unlawful intercepters in Greece between 2004 and 2005.
These are the stories you need to keep in mind when thinking about proposals to ensure that all communications systems can be eavesdropped on by government. Both the FBI's James Comey and UK Prime Minister David Cameron recently proposed limiting secure cryptography in favor of cryptography they can have access to.
But here's the problem: technological capabilities cannot distinguish based on morality, nationality, or legality; if the US government is able to use a backdoor in a communications system to spy on its enemies, the Chinese government can use the same backdoor to spy on its dissidents.
Even worse, modern computer technology is inherently democratizing. Today's NSA secrets become tomorrow's PhD theses and the next day's hacker tools. As long as we're all using the same computers, phones, social networking platforms, and computer networks, a vulnerability that allows us to spy also allows us to be spied upon.
We can't choose a world where the US gets to spy but China doesn't, or even a world where governments get to spy and criminals don't. We need to choose, as a matter of policy, communications systems that are secure for all users, or ones that are vulnerable to all attackers. It's security or surveillance.
As long as criminals are breaking into corporate networks and stealing our data, as long as totalitarian governments are spying on their citizens, as long as cyberterrorism and cyberwar remain a threat, and as long as the beneficial uses of computer technology outweighs the harmful uses, we have to choose security. Anything else is just too dangerous.
Bruce Schneier is a security technologist and author. He is the CTO of Resilient Systems, Inc., and his latest book is Data and Goliath: The Hidden Battles to Collect Your Data and Control Your World. He blogs at schneier.com.