• Question: How does your secret code work?

    Asked by Matthew to Freya on 18 Jun 2015.
    • Photo: Freya Wilson

      Freya Wilson answered on 18 Jun 2015:

      Aha. That would be telling 😉

      So we can make a lock that is complete secure- that is already a thing. The hard part is making the key. I want a key and my friend wants a key that are the same, and the enemy needs to be incapable of copying the key. Copying the key is how most hackers get into stuff now.

      It is based on something called the uncertainty principle. This means that you can’t know all the properties of an electromagnetic wave.- you can say where it is, but you wouldn’t know its movement, or you can describe its movement fully but you couldn’t know its position. It’s a bit weird, and one of the founding aspects of quantum physics.

      One effect of this also means that if two people measure the wave, they will get different answers. So if I want to send you a secret message, and an enemy measures it as well as you then the enemy will get something different. So you tell me a little bit about what you have, which isn’t enough to help the enemy, and I use that to figure out what it was exactly that you had. Then we both have the same information and we can use that as our key…

      Does that sort of make sense?

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