What’s different about digital security?

With regards to the current cryptowars going on, it seems like there’s a bit of a misunderstanding amongst the public (and decision makers) as to why digital security is different from physical security.

A month or two ago, the FBI, was attempting to compel Apple to create a backdoor into their operating system’s memory encryption. This is basically the idea of there being a master key for decrypting your communications that the government would have access to if necessary.

Looking at it from a politician’s or a cop’s perspective, buildings housing information far more sensitive than people’s email, passwords and bank account numbers might have master keys, and society seems to get along just fine. Sometimes bad things happen, but you can change the locks if you find out the lock was compromised. In any case, how do you investigate crimes if the evidence is unreadable? Law enforcement has to be able to investigate to do their job (though no one said their job had to be easy). Other people have written good rebuttals to the latter aspect, but I think there’s a consideration due to the former that’s missing from the public imagination: scale and distance.

Computer people talk about perfect security in a way that is incomparable to security in the real world. In encryption and authentication, security is measured by mathematical proofs. In the real world, security is measured by much sloppier metrics. For instance, a bike lock is by no means a guarantor of security. Believe me — I’ve lost three bikes.

However, if someone exploits a bike lock, they have to go bike by bike (or assemble a mob to go bike by bike) to exploit it. This requires physical movement and time. It’s easy for the cops to notice a gang bum rushing a bike rack. While it can cause other kinds of social problems, cops often try to contain crime into particular neighborhoods or at least try to prevent it from leaking into other particular ones. The fact that the world is topologically a sphere is actually very important to our security posture. It takes distance to move from place to place, and distance means both time and energy.

In the digital world, there are no good neighborhoods and bad neighborhoods. There’s only one neighborhood and everyone lives on the same street. The mob lives next door to grandma — and grandma can never move away.

Imagine a crack team of North Korean bike thieves wanted to steal my bike. They’d have to hop on a boat or plane, pass US customs somehow, get to my city, and crack my stupid lock. Now imagine a team of North Korean hackers wanted to steal my banking information and knew a way to crack my encrypted communications. All they have to do is run a few computers for a bit after intercepting my communications from a world away. This is quite a safe thing for them to do, and it’s not very cost or labor intensive.

The second aspect of digital security is scale. Once you have a break in an algorithm, you can start exploiting it on a scale comparable to an invading army in the real world. Maybe that doesn’t quite do it justice as an army typically invades one or two countries at a time. These guys would be capable of attacking every country that uses that algorithm at once at high speed. To return to the bike thief comparison, this is like giving them a hypersonic stealth helicopter with insane range. Before, the ocean was a barrier; now, not so much.

This is the flaw in the FBI’s calculations. Digital security isn’t like physical security. If you put a master key into our digital communications, the discovery of the master key by criminals and nation states won’t be easily contained — and it’s going to happen.

This article was published 4 months after it was written. Thank you to Kane Hadley for the conversation that lead to this piece.

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