What are decentralized identifiers and credentials?

Let’s start by saying that KILT Protocol is a system for maintaining identities. And here comes the first interesting part: an identity is not the same as an identifier. 

If an identifier is just a name or a number – it doesn’t say anything about an identity. So for example, if your name is Alex, that doesn’t say where you’re from, it doesn’t say where you are working, whether you have a driving license or not; it doesn’t say anything about you. It doesn’t really contain any information, it’s just an identifier. And if there is only one Alex here and someone directs a question to Alex, you know they’re talking to you. But if there are two people called Alex in the room you never know, so it would be good to have those identifiers a little bit unique.

This is the first part: Identity starts with an identifier, which is what all the other things are linked to. And many of these things in our world are linked to the identifier with credentials. So think of real life; If you are Alex, you have a passport  that basically says “Alex”. And it also has a picture of you, and other things, but it can be directly linked to you because you are Alex and the word Alex is there on the passport. But the passport gives more information about you because, for example, it says where you’re from. And this passport is what we call a credential.

So identity is built by adding more and more credentials to an identifier.

If you want to build a digital identity you need both an identifier – for people or things – and then you need different types of credentials which are linked to the identifier. Then step by step you produce a digital identity.

And this can also be done for machines. The identifier of the device could be a very long number for example. This device can be identified by this number because this number is unique to it. And then, step by step you add more and more credentials to it, like an IOT device that is compatible with a certain standard, for example. Then the device gets an identity. And if the identifier is registered on the blockchain it becomes decentralized, because the blockchain doesn’t store information in any one location; it’s spread across a network of computers.