Create a DID-Linked Resource

Create a DID-Linked Resource (DLR), linked to a Decentralized Identifier (DID) on cheqd, using Veramo.

Follow these instructions to create a new DID-Linked Resource on cheqd mainnet or testnet.

⚠ī¸ Before you begin...

Make sure you've correctly configured the cheqd plugin's agent settings for Veramo CLI

Instructions

1. Create a DID

Follow this tutorial to generate keys and create a DID.

2. Create your Resource content and save the file locally

DID-Linked Resources can be any type of file or content that is below ~200kb in size.

For the purpose of an example, lets use an AnonCreds schema (JSON file) as the resource:

{
  "name": "degreeSchema",
  "version": "1.5.7",
  "attrNames": ["name", "age", "degree", "grade"]
 }

Save this file locally and call it something like resource.json.

3. Create a UUID for the Resource

UUIDs are used to identify DID-Linked Resources. On Unix systems, the uuidgen tool can be used to generate a new UUID:

$ uuidgen
e7b662f8-d3f8-4a83-bd00-2cdcd6cc50ab

4. Choose an option for passing the resource that best suits you

Option 1: Passing resource as Base64

Prepare a file with resource and encode it into base64. On Unix systems, you can use the following command input:

$ base64 -w 0 resource.json
<path-to-the-resource-file>

Expected output:

$ base64 -w 0 resource.json
SGVsbG8sIHdvcmxk

You will need to paste the output of the Base64 into the data field of the payload.json file as shown in step 5.

Option 2: Passing resource as file

Once you have saved your Resource file locally, you can copy the path and enter it in the file field of the payload.json file as shown in step 5.

5. Prepare your payload file

Before carrying out a Resource transaction, you will need to prepare the payload.json file. This file can be saved wherever you choose, but the location must be specified in the create Resource command. (By default, it will be saved under the project root directory.)

Parameters

  • kms (default local): Key Management System (KMS) to be used for storage;

  • payload: Resource definition

    • collectionId: The last fragment of the corresponding DIDDoc

    • id: Use output from the previous step here

    • name: Arbitrary human-readable string used to identify the resource

    • resourceType: Resource type, such as CL-Schema, JSONSchema2020, etc

    • version: (Optional) client-given resource version

    • alsoKnownAs: (Optional) alternative URI(s) provided for the resource

    • data: (Optional) base64 encoded data of resource file

  • signInputs: Keys used to sign the corresponding DIDDoc. These must match the ones specified in the DIDDoc, otherwise an error will be thrown

    • verificationMethodId: Verification method ID from DIDDoc where key is published

    • keyType should match values that you used to create the DIDDoc

    • privateKeyHex should match values that you used to create the DIDDoc

  • file: (Optional) path to resource file

  • fee:

    • amount: An array of coins, coins are represented as an object with 2 fields

      • denom: ncheq (smallest denomination classification)

      • amount: See section below on fees

    • gas: Each transaction must specify the maximum amount of gas it may consume.

    • payer (Optional): The cheqd fee payer address

    • granter (Optional): The cheqd fee granter address, Provided the grantee has an allowance by the granter

The Payload file can include a Resource passed either as a file or a base64 encoded string:

Example Payload file for passing Resource as Base64 encoded string
{
    "kms": "local",
    "payload": {
        "collectionId": "d3e515cf-81af-40cb-9ac1-154827986d29", // unique ID of associated 'parent' DID
        "id": "e7b662f8-d3f8-4a83-bd00-2cdcd6cc50ab",
        "name": "TestResource",
        "resourceType": "JsonDocument",
        "version": "",
        "alsoKnownAs": [],
        "data": "SGVsbG8sIHdvcmxk" // note that the base64 encoded content is passed here
    },
    "network": "testnet",
    "signInputs": [{
        "verificationMethodId": "did:cheqd:testnet:d3e515cf-81af-40cb-9ac1-154827986d29#key-1",
        "keyType": "Ed25519",
        "privateKeyHex": "0f5c124886178037952e87e0cdc55d185732577fca19ae877e64ac9ab24a0cc534e5326e70f1a42d785d93048aee806c359ec75a7b06f39253befd1746708438"
    }],
    "fee": {
      "amount": [{
        "denom": "ncheq",
        "amount": "2500000000" // 2.5 CHEQ is the fixed fee for a JSON transaction
        }],
      "gas": "1000000",
      "payer": "cheqd1rnr5jrt4exl0samwj0yegv99jeskl0hsxmcz96" // must match the account set in the agent.yaml file
    }
}
Example Payload file for passing Resource as file
{
    "kms": "local",
    "payload": {
        "collectionId": "d3e515cf-81af-40cb-9ac1-154827986d29",
        "id": "e7b662f8-d3f8-4a83-bd00-2cdcd6cc50ab",
        "name": "TestResource",
        "resourceType": "JsonDocument"
        "version": "",
        "alsoKnownAs": []
    },
    "network": "testnet",
    "signInputs": [{
        "verificationMethodId": "did:cheqd:testnet:d3e515cf-81af-40cb-9ac1-154827986d29#key-1",
        "keyType": "Ed25519",
        "privateKeyHex": "0f5c124886178037952e87e0cdc55d185732577fca19ae877e64ac9ab24a0cc534e5326e70f1a42d785d93048aee806c359ec75a7b06f39253befd1746708438"
    }],
    "file": "/path/to/resource.json", // note that the resource passed as file is inputted here
    "fee": {
      "amount": [{
        "denom": "ncheq",
        "amount": "2500000000" // 2.5 CHEQ is the fixed fee for a JSON transaction
        }],
      "gas": "1000000",
      "payer": "cheqd1rnr5jrt4exl0samwj0yegv99jeskl0hsxmcz96" // must match the account set in the agent.yaml file
    }
}

6. Understanding Resource Fees

The maximum file size for a resource is roughly 46KB which may require a gas fee of up to 2000000.

The fee for a resource transaction changes depending on the file type being passed to the ledger. Currently there are three different variations on the fee:

JSON file

Within the payload file the amount should be specified as:

  • denom: ncheq

  • amount: 2500000000

This equates to 2.5 CHEQ.

Image file

Within the payload file the amount should be specified as:

  • denom: ncheq

  • amount: 10000000000

This equates to 10 CHEQ.

Note that images may also require a larger 'gas' fee of up to 2000000

Default (any other) file

Within the payload file the amount should be specified as:

  • denom: ncheq

  • amount: 5000000000

This equates to 5 CHEQ.

Note that transaction fees are paid by the cheqd account set in the agent.yml configuration file, setup here. If you do not specify a fee in the transaction, the ledger will automatically deduct the appropriate fee from the account set in youragent.yml configuration. Each of cheqd's on-ledger identity transactions has a fixed fee, the pricing for cheqd DIDs and DID-Linked Resources can be found here. If your account has insufficient balance the transaction will fail.

7. Create new DID-Linked Resource

veramo execute -m cheqdCreateLinkedResource --argsFile path/to/payload.json

If you do not specify the --argsFile in the previous step, you can also paste a JSON inline argument object by using the --argsJSON flag followed by the JSON payload.

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