saveVC

How to call the API from an app

Identify Snap connects to your currently connected Metamask account by default. To learn how apps can connect to Identify Snap using a non-metamask(external) account, refer to this documentation.

Then, depending on whether you're trying to connect to a metamask account or a non-metamask account, you can call the snap API in the following way:

const snapId = `npm:@tuum-tech/identify`

/*
  The 'data' parameter should be an array of 'W3CVerifiableCredential'.
  W3CVerifiableCredential represents a signed Verifiable Credential (includes proof)
  in either JSON or compact JWT format. 
*/
const data = [
  {
    credentialSubject: {
      profile: {
        name: 'KP'
      },
      id: 'did:pkh:eip155:1:0x2e5ff0267b678a0faf9a9f5b0fbf7ac9638b5b57'
    },
    issuer: {
      id: 'did:pkh:eip155:1:0x2e5ff0267b678a0faf9a9f5b0fbf7ac9638b5b57'
    },
    type: ['VerifiableCredential', 'ProfileNamesCredential'],
    '@context': ['https://www.w3.org/2018/credentials/v1'],
    issuanceDate: '2023-04-05T14:34:47.000Z',
    expirationDate: '2024-04-05T14:34:47.000Z',
    proof: {
      type: 'JwtProof2020',
      jwt: 'eyJhbGciOiJFUzI1NksiLCJ0eXAiOiJKV1QifQ.eyJleHAiOjE3MTIzMjc2ODcsInZjIjp7IkBjb250ZXh0IjpbImh0dHBzOi8vd3d3LnczLm9yZy8yMDE4L2NyZWRlbnRpYWxzL3YxIl0sInR5cGUiOlsiVmVyaWZpYWJsZUNyZWRlbnRpYWwiLCJQcm9maWxlTmFtZXNDcmVkZW50aWFsIl0sImNyZWRlbnRpYWxTdWJqZWN0Ijp7InByb2ZpbGUiOnsibmFtZSI6IktQIn19fSwic3ViIjoiZGlkOnBraDplaXAxNTU6MToweDJlNWZmMDI2N2I2NzhhMGZhZjlhOWY1YjBmYmY3YWM5NjM4YjViNTciLCJuYmYiOjE2ODA3MDUyODcsImlzcyI6ImRpZDpwa2g6ZWlwMTU1OjE6MHgyZTVmZjAyNjdiNjc4YTBmYWY5YTlmNWIwZmJmN2FjOTYzOGI1YjU3In0.CR1A_XpG001_PCaAt3VN9G5Lt75gTm2M5YSt6trqhkEoW0wce9rU7SrsZnQ0drmaG2tee4IMrZFx241yi8UsLg'
    }
  }
]

const options = {
  // If you want to auto save the generated VCs to multiple stores, you can pass an
  // array like so:
  // store: ['snap', 'googleDrive']
  store: ['snap']
}

const metamaskAddress = '0x2e5fF0267b678A0FAF9A9f5b0FBf7Ac9638B5b57'
const params = {
  metamaskAddress,
  data,
  options
  /* 
    Uncomment the below line if you want to connect to a non-metamask account
  */
  // ...externalAccountParams
}

const handleSaveVCAPI = async () => {
  await window.ethereum.request({
    method: 'wallet_invokeSnap',
    params: {
      snapId,
      request: {
        method: 'saveVC',
        params: params
      }
    }
  })
}

Notes:

• There is no need to pass in options if you want to store the VC in the Metamask snap state as this is the default behavior however, for storing it in googleDrive, you will need to specify via this parameter. In order to use googleDrive , you first need to first configure your google account.

• Identify Snap currently supports generating VC using jwt proof format however, it still supports the saving of other types of VCs with other proof formats such as lds and EthereumEip712Signature2021.

How the API is handled between the app and snap

What the API does

1. Retrieves the currently connected account and the blockchain network the user has selected on Metamask. If it's the first time, the account info is also saved in snap state.

2. Saves the passed in signed Verifiable Credential(VC) to the appropriate storage(eg. snap/googleDrive).

3. Returns the metadata for the saved VC that contains the unique vc Id and the store at which the VC was saved in.

Some example responses:

[
    {
        'id': '532e0b77-fd00-47cf-8b62-daf6f5326eae',
        'store': 'snap'
    }
]

How the API works

https://github.com/tuum-tech/identify/blob/main/packages/snap/src/rpc/vc/createVC.ts

import { divider, heading, text } from '@metamask/snaps-ui';
import { ProofFormat, W3CVerifiableCredential } from '@veramo/core';
import cloneDeep from 'lodash.clonedeep';
import { v4 as uuidv4 } from 'uuid';
import { validHederaChainID } from '../../hedera/config';
import { IdentitySnapParams, SnapDialogParams } from '../../interfaces';
import {
  IDataManagerSaveResult,
  ISaveVC,
  SaveOptions,
} from '../../plugins/veramo/verifiable-creds-manager';
import { generateCommonPanel, snapDialog } from '../../snap/dialog';
import { getCurrentNetwork } from '../../snap/network';
import { getAccountStateByCoinType } from '../../snap/state';
import {
  CreateVCRequestParams,
  CreateVCResponseResult,
} from '../../types/params';
import { getVeramoAgent } from '../../veramo/agent';

/**
 * Function to create VC.
 *
 * @param identitySnapParams - Identity snap params.
 * @param vcRequestParams - VC request params.
 */
export async function createVC(
  identitySnapParams: IdentitySnapParams,
  vcRequestParams: CreateVCRequestParams,
): Promise<CreateVCResponseResult> {
  const { origin, snap, state, metamask, account } = identitySnapParams;

  // Get Veramo agent
  const agent = await getVeramoAgent(snap, state);

  // GET DID
  const { did } = account.identifier;

  const {
    vcKey = 'vcData',
    vcValue,
    credTypes = [],
    options,
  } = vcRequestParams || {};
  const { store = 'snap' } = options || {};
  const optionsFiltered = { store } as SaveOptions;

  const dialogParams: SnapDialogParams = {
    type: 'confirmation',
    content: await generateCommonPanel(origin, [
      heading('Create Verifiable Credential'),
      text('Would you like to create and save the following VC in the snap?'),
      divider(),
      text(
        JSON.stringify({
          [vcKey]: vcValue,
        }),
      ),
    ]),
  };

  if (await snapDialog(snap, dialogParams)) {
    const issuanceDate = new Date();
    // Set the expiration date to be 1 year from the date it's issued
    const expirationDate = cloneDeep(issuanceDate);
    expirationDate.setFullYear(
      issuanceDate.getFullYear() + 1,
      issuanceDate.getMonth(),
      issuanceDate.getDate(),
    );

    const credential = new Map<string, unknown>();
    credential.set('issuanceDate', issuanceDate.toISOString()); // the entity that issued the credential+
    credential.set('expirationDate', expirationDate.toISOString()); // when the credential was issued
    credential.set('type', credTypes);

    const issuer: { id: string; hederaAccountId?: string } = { id: did };
    const credentialSubject: { id: string; hederaAccountId?: string } = {
      id: did, // identifier for the only subject of the credential
      [vcKey]: vcValue, // assertion about the only subject of the credential
    };
    const chainId = await getCurrentNetwork(metamask);
    const accountState = await getAccountStateByCoinType(
      state,
      account.evmAddress,
    );
    if (validHederaChainID(chainId)) {
      const hederaAccountId = accountState.extraData as string;
      issuer.hederaAccountId = hederaAccountId;
      credentialSubject.hederaAccountId = hederaAccountId;
    }
    credential.set('issuer', issuer); // the entity that issued the credential
    credential.set('credentialSubject', credentialSubject);

    // Generate a Verifiable Credential
    const verifiableCredential: W3CVerifiableCredential =
      await agent.createVerifiableCredential({
        credential: JSON.parse(JSON.stringify(Object.fromEntries(credential))),
        // digital proof that makes the credential tamper-evident
        proofFormat: 'jwt' as ProofFormat,
      });

    // Save the Verifiable Credential to all the stores the user requested for
    const saved: IDataManagerSaveResult[] = await agent.saveVC({
      data: [{ vc: verifiableCredential, id: uuidv4() }] as ISaveVC[],
      options: optionsFiltered,
      accessToken:
        accountState.accountConfig.identity.googleUserInfo.accessToken,
    });

    // Retrieve the created Verifiable Credential
    const result: CreateVCResponseResult = {
      data: verifiableCredential,
      metadata: {
        id: saved[0].id,
        store: saved.map((res) => res.store),
      },
    };

    console.log(
      'Created and saved verifiableCredential: ',
      JSON.stringify(result, null, 4),
    );
    return result;
  }
  throw new Error('User rejected');
}

Live Demo on CodePen

Some things to keep in mind while interacting with the above demo

• If you're getting any errors with the live demo, make sure you go through the FAQs section to learn about what you may be missing. You need to install Metamask in your browser for the live demo to work

• Whenever there is a new version of the IdentifySnap, always make sure to first uninstall the old version of the snap from Metamask and only then try the above demo so it can install the latest version

To ease the integration of Identify Snap on an application, we have created a template web application that you can run locally and check out the code in its entirety to learn how you can integrate and interact with various APIs exposed by Identify Snap. Check out the full source code at template application github repository.

You can also check out the API reference to learn how each API works.