by Paul Curzon, Queen Mary University of London
If you are so power hungry you can’t stand the idea of any opposition; if you want to make a grab for total power, so decide to crush everyone in your way, then you might want to think about the security of your power supply first. Luckily, all would-be dictators who crush everyone who gets in their way as they march towards total domination of the galaxy, tend to be very naive about cyber-security.
Take Ronan the Accuser in the original Guardian of the Galaxy film. He’s a villain with a religious streak, whose belief that strength is virtue and weakness is sin leads to his totally corrupted morality. To cut to the guts of the story he manages to get the “Infinity Stone” that gives unimaginable power to its owner. With it he can destroy anyone who gets in his way so sets out to do so.
Luckily for the Galaxy, good-guy Peter Quill, or Star-Lord as he wants to be known, and his fellow Guardians have a plan. More to the point they have Gamora. She is an assassin originally sent to kill Quill, but who changes sides early on. She is an insider who knows how Ronan’s security system works, and it has a flaw: its big, heavy security doors into his control room.
Security Lesson 1. It should still be secure even when the other side know everything about how it works. If your security relies on no one knowing, its almost certainly bad security!
Electromagnetic locks are used all over the place and they give some big advantages, such as the fact that they mean you can program who is and isn’t allowed entry. Want to keep someone out – you can just cancel their keycard in the system. They are held locked by electromagnets: magnets that are switched on and off using an electric current. That means computers can control them. As the designer of an electromagnetic lock you have a choice, though. You can make them either “fail safe” or “fail secure”. With a fail safe lock, when the power goes, the doors automatically unlock. With fail secure, instead they lock. Its just a matter of whether the magnet is holding the door open or closed. Which you choose when designing the lock depends on your priorities.
Fail safe is a good idea, for example, if you want people to be able to escape in an emergency. If a fire cuts the electricity you want everyone to still be able to get out, not be locked in with no chance of escape. Fail secure on the other hand is good if you don’t want thieves to be able to get in just by cutting the power. The magnets hold the bolts open, so when the power goes, the spring shut.
Security Lesson 2. If you want the important things to stay secure, you need a fail secure system.
There is one last thing that could have saved Ronan. It needed an uninterruptible power supply.
Security Lesson 3. If your system is reliant on the power supply, whether a door, your data, your control system or your life-support system, then it should keep going even if the power is switched off.
After all, what if the space ships cleaners (you never see them but they must be there somewhere!) unplug the door lock by mistake just because they need somewhere to plug in the hoover.