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Using the Essentials DID Toolkit

A decentralized identifier (DID) adapter is required to publish transactions to the Elastos Identity (EID) chain.

The easiest way to work with DIDs on the EID chain is to use the Elastos Essentials connector, which provides a DID adapter over WalletConnect.

This abstracts most of the logic for developers and lets the wallet handle all transaction signing.

Setup​

Start by installing the packages:

# Connectivity SDK
npm install @elastosfoundation/elastos-connectivity-sdk-js

# Use at least one connector
npm install @elastosfoundation/essentials-connector-client-browser

# Use the DID SDK as it's needed for most interactive operations
npm install @elastosfoundation/did-js-sdk

Register the Connector​

import { connectivity } from "@elastosfoundation/elastos-connectivity-sdk-js";

let essentialsConnector = new EssentialsConnector();

// Let the connectivity SDK know that we are willing to use this connector.
connectivity.registerConnector(essentialsConnector);

Instantiate the DID Access Helper​

The DID access helper makes it easy to execute remote operations in the wallet in just a few lines of code. All of the below examples use an instance of this helper tool that are created as follows:

// Connectivity SDK classes
import { DID as ConnDID } from "@elastosfoundation/elastos-connectivity-sdk-js";

// DID SDK classes, used to manipulate inputs/outputs to the connectivity SDK
import {
  DID,
  DIDBackend,
  DIDStore,
  Issuer,
  Mnemonic,
  RootIdentity,
  VerifiableCredential,
} from "@elastosfoundation/did-js-sdk";

let didAccess = new ConnDID.DIDAccess();

Fetch User DID credentials​

In order for a third party application to get a user's "DID string" (DID identifier) or email, it can request the identity wallet to "get some credentials". Here's how it works:

// Request credentials from the wallet
let presentation = await didAccess.getCredentials({
  claims: {
    name: true, // Mandatory
    avatar: {
      required: false, // Optional
      reason: "Show who you are to others"
    }
});

// The returned information is a Verifiable Presentation that contains
// one or more credentials. The DID SDK can then be used to manipulate
// those credentials.
let nameCredential = presentation.getCredentials().find((c) => {
  // Find the "name" credential
  return c.getId().getFragment() === "name";
});

console.log("Thank you for joining " + nameCredential.getSubject().getProperty("name"));
tip

For more operations and complete instructions on using the Essentials connector, visit the Connectivity SDK guide.