How quantum mechanics can keep your data safe from spies

Richard Feynman, who won a Nobel prize for his work in theoretical physics, once said: “I think I can safely say nobody understands quantum mechanics.”

He was in good company. Before him, probably the most famous physicist of all time, Albert Einstein, was also nonplussed.

“The world cannot be that crazy,” he once said. “However, nowadays we know that it is.”

So it is probably not a surprise that quantum mechanics has become an increasingly hot topic, in a post-NSA world, for people who are looking to obscure, encrypt and even hide information.

I think I can safely say nobody understands quantum mechanics. Physicist Richard Feynman

But that is not just because nobody understands what is going on. It is because leading physicists and cryptographers have found ways to use quantum mechanics – basically a branch of physics looking at what happens to the world when things are really, really small – to make communications more secure.

As Gregoire Ribordy, chief executive of encryption company ID Quantique, put it: “The world has changed a lot. A year ago the information came out about the NSA collecting information in phone calls. That was the first leak of the Snowden scandal. Following this lots of other information came out… How can we prevent these kinds of attacks? Information technology is going to be quantum physics.”

And here’s one important way how.

Cracking the code

At the moment, when two parties want to send secure information to each other, it is encrypted, then decrypted, using keys built with mathematical algorithms. But the keys, if intercepted, are vulnerable to being cracked: although the idea is that cracking them is hard, the more powerful computers get, the easier this will become.

The idea with quantum communications, without going into the frankly mindboggling detail, is that the codes or keys can be sent in such a way – using tiny particles – that the parties can tell if they have been intercepted. This is one of the laws of quantum mechanics: when you measure or interfere with the system, you affect it.

Mr Ribordy said one way to look at this is comparing it with tennis balls and bubbles. If you wrote a message on a tennis ball, threw it to a friend, and someone caught it in the middle, they could read the message and pass it on and nobody would be any the wiser. In quantum communications, the message is written on a bubble; if someone catches it to intercept that message on the way to its final destination, it bursts.

So the key codes are built on the same principle in quantum communications as they currently are – but because you can tell if they have been intercepted, you can prevent a leak because you would not use the code if this had happened. It’s a “what they don’t know, can’t hurt us” scenario. It is called quantum key distribution, and it is already being used by government and banking data centres to keep communications safe from prying eyes – whether those eyes belong to other governments or hackers.

But hang on a minute…

But there is another side to the quantum coin too: quantum computing.

Again using complex quantum mechanics, quantum computers can complete calculations far faster than conventional computers, even super computers. A proper quantum computer does not currently exist, but physicists agree it is coming soon.

And why does this matter? Well, remember those keys for getting into encrypted information? As aforementioned, at the moment, the maths behind them would take a computer a long time to work out. For a quantum computer – not so much.

And the NSA wants in: in January its interest in quantum computing hit the headlines, although experts suggest it has been looking into the technology for far longer than that.

So while quantum computing represents a huge problem for people who want to keep their data secure – because quantum computers will soon be able to crack the encryption codes – it also, simultaneously, presents a potential solution via quantum communications.

And to be honest, that is just typical of this field. No wonder even Einstein was confused.