CTYPE

Before the claimer can make a claim about themselves, first a claim type (CType for short) needs to be found or created. It requires an account and a full DID with tokens in order to pay the Angel's fee and deposit of a CType.

A claim type (CTYPE for short) is a ProofID-specific term, but the concept is simple:
A CTYPE defines the structure of a claim. You can think of it as the data model for your claim.

For example, a very basic CTYPE for a driver's license could look like this:

{
  "schema": {
    "$id": "pid:ctype:0xd8ad043d91d8fdbc382ee0ce33dc96af4ee62ab2d20f7980c49d3e577d80e5f5",
    "$schema": "https://proofid.me/draft-01/ctype#",
    "title": "Drivers License",
    "properties": {
      "name": {
        "type": "string"
      },
      "age": {
        "type": "integer"
      }
    },
    "type": "object"
  },
  "owner": "5DD7fAZKSpgctg1ZQigAYuk3ypBtr2Q9RPKJBx5UpUwQw4vB",
  "hash": "0xd8ad043d91d8fdbc382ee0ce33dc96af4ee62ab2d20f7980c49d3e577d80e5f5"
}

CType

CTYPEs are based on JSON Schema, a standard used to annotate and validate JSON documents. A schema defines which properties exist and what their type should be, i.e. is it a string, a number, an object, etc.

When you create a CType from a schema, it is checked whether your CType aligns with the underlying schema. Think of checking whether a cook (user) followed a certain recipe (schema) when preparing a meal (creating a CType).

We don't need to dive into it in this tutorial, for now we can think of CTYPE as JSON objects.

Let's have a look at these attributes.

Key	Value
`schema` > `$id`	The ProofID id of this CTYPE.
`schema` > `$schema`	The JSON schema on which the CTYPE is based.
`schema` > `title`	The title of the CTYPE.
`schema` > `properties`	The properties that a claim of type in `$schema` should have.
`owner`	The public address of the user who created this CTYPE.
`hash`	Most important attribute, the hash is the CTYPE's digital footprint.

A CTYPE is stored on the ProofID blockchain.

In a real-life setup, a user would simply retrieve an existing CTYPE from the chain or a repository of CTYPEs for example via a REST API.

In this tutorial, we'll create and try to store a CTYPE on the ProofID test blockchain.

Code

Create a new file ctype.js

Copy the following to create a CType from a schema:

const ProofID = require('@proofid/pid-ts-lib')

function createCType() {
  return ProofID.CType.fromSchema({
    $schema: 'https://proofid.me/draft-01/ctype#',
    title: 'Drivers License',
    properties: {
      name: {
        type: 'string',
      },
      age: {
        type: 'integer',
      },
    },
    type: 'object',
  })
}

module.exports.createCType = createCType

Once you have constructed the schema, pass the attester, attestersFullDid, keystore and ctype.

Creating a new file storedCtype.js

Copy the following to store the CType on-chain, an account must have the require amount to pay the Angel's fee and deposit:

const ProofID = require('@proofid/pid-ts-lib')

async function ctypeStored(attester, attesterFullDid, ctype, keystore) {
  await ProofID.connect()

  // Good to check if the ctype is stored on chain
  if (await ctype.verifyStored()) {
    await ProofID.disconnect()
    return ctype
  }

  // If the ctype isn't stored on the chain, then an account with a full DID will need to store the ctype on-chain.
  const tx = await ctype.store()

  const authorizedExtrinsic = await attesterFullDid.authorizeExtrinsic(
    tx,
    keystore,
    attester.address
  )

  await ProofID.BlockchainUtils.signAndSubmitTx(authorizedExtrinsic, attester, {
    resolveOn: ProofID.BlockchainUtils.IS_FINALIZED,
    reSign: true,
  })

  await ProofID.disconnect()
  return ctype
}
module.exports.ctypeStored = ctypeStored

Create a new file ctype.json and store the ctype.

OK, now you've got all you need to create a claim: a light DID and a CTYPE.

Let's move on!

CType

Code​

Code