If your car has only two keys, it is no problem for you to start your car. If your car has four keys, things get a bit trickier. If you want to start your car with only a single key, you either need a symmetric key or you need to store a copy of the car’s serial number.
It’s pretty fun to say, but we can’t be sure whether there’s any real difference between using a single key vs. a symmetric key. But it doesn’t seem to matter, because one key opens the car, and the other key opens the trunk. Either way, the trunk stays shut.
Symmetric key cryptography is the process by which a single key is used to encrypt data that is then used to decrypt the same data, thus making it impossible to duplicate the data. The concept is the same as how an ATM works. If you have a key that opens the trunk, you can use that single key to get your car started. If you have a key that opens the car, you can use that single key to get your car started.
Symmetric key cryptography is a well-known and useful concept, however in this case the single key is used for both the trunk and the car. The only way to duplicate the data is to use the same key to unlock both the trunk and the car.
While this is true, it’s not what’s being described. The idea here is that a key that opens the trunk and the key that opens the car are the same key. So if you have two keys that both open the trunk and the car, you can duplicate them both and use the trunk key to start the car. But you can’t duplicate the key that opens the trunk or the key that opens the car.
The key that opens the trunk is the key that opens the car. To duplicate the key that opens the trunk, the trunk key needs to be added to the car key chain. This is not true for keys like the one highlighted above. In fact, an older key chain may have less key to use than a newer key chain.
The key chain that’s used in symmetric encryption is asymmetric. So one key doesn’t just have to be used to duplicate the other key. In fact, you can have more than two keys that could be used to duplicate each other. For example, in the first scenario above, you can have two keys that both open the trunk and the car.
And this is useful for those who want to store more than one key in a location. For example, if you’re going on a road trip, you could use one key to unlock your car and another key to unlock your trunk. If the trunk is locked while you’re in the car, you could use both keys at the same time, unlocking the trunk, then unlocking the car.
There is a lot of literature on this topic.
But in the end, this whole thing is a bit of a black art. If you want to start using symmetric encryption for key storage you’re going to need to spend a lot of time learning about it. It’s not for the faint of heart. And the whole thing can be a bit complicated. I’ve read a lot about this subject myself and have been very confused when I’ve ended up being a bit stumped by the subject.