Learn how to build and configure a web application that can verify mDocs

Create a verifier application configuration

Each MATTR VII tenant can interact with multiple verifier applications, and can handle requests differently for each application. This means you must create a verifier application configuration that defines how to handle verification requests from your web application.

1. Expand the Credential Verification section in the left-hand navigation panel.
2. Select Applications.
3. Select the Create new button.
4. Use the Name text box to insert a meaningful and friendly name for your application.
5. Use the Type radio button to select Web.
6. Use the Allowed domains text box to insert a placeholder domain name (e.g. place-holder.com). This indicates domain names that the MATTR VII tenant can verify incoming requests are from known and trusted applications. You will update this placeholder value later.
7. Use the Redirect URIs text box to insert a placeholder redirect URI (e.g. https://place-holder.com). This is the URI the user would be redirected to after presenting a credential on a same-device flow. You will update this placeholder value later.
8. Select the Create button to create the new application and display the Application detail screen.
9. Copy and record the ID value. You will use it later in the tutorial.

Create a supported wallet configuration

Verifier web applications can define specific wallet applications to accept mDocs from as part of their verification workflows. The MATTR VII verifier tenant needs to be configured with a specific URI scheme that will be used to invoke these wallets.

1. Expand the Credential Verification section in the left-hand navigation panel.
2. Select Supported wallets.
3. Select the Create new button.
4. Use the Name text box to insert a meaningful and friendly name for your wallet application (for example “MATTR GO Hold”).
5. Use the Authorize endpoint text box to insert mdoc-openid4vp://. This is the URI scheme that will be used to invoke the wallet application. You can learn more about URI scheme selection logic here.
6. Select the Create button to create the new wallet configuration.

Configure a trusted issuer

You must configure trusted issuers on your MATTR VII verifier tenant, as presented mDocs will only be verified if they had been issued by a trusted issuer.

This is achieved by providing the PEM certificate of the IACA used by these issuers to sign mDocs. In production environments the issuer can provide it out of band or you can obtain it via their issuer’s metadata.

1. Expand the Credential Verification section in the left-hand navigation panel.
2. Select Trusted issuers.
3. Select the Create new button.
4. Use the Certificate PEM file to upload the following file  (ensure you extract the ZIP file and upload the .pem file itself). This is the IACA certificate that identifies the MATTR Labs demo issuer  which issues the credential referenced in the prerequisites section.
5. Select the Add button to add the new trusted issuer.

This completes the configuration of the MATTR VII verifier tenant. In the next step, you will build a simple application that you can run locally to test the verification workflow and ensure everything is functioning as expected.

Setup your environment

1. Open your terminal and create a new NextJS default project:

npx create-next-app@latest --src-dir --yes

2. Approve installing any required packages.
3. Insert a name for your project (e.g. my-verifier-web-application).
4. Open the project app’s folder:

cd my-verifier-web-application

5. Install the SDK:

npm install @mattrglobal/verifier-sdk-web

6. Open the src/app/page.tsx file in your preferred code editor and replace all existing code with the following:

'use client'
 
// Step 3.2 - Add dependencies
 
export default function Home() {
    // Step 5.1 - Store results state
 
    // Step 6.1 - Create createRequest function
 
    // Step 4.1 - Create requestCredentials function
 
    // Step 5.3 - Handle same-device redirect
 
    // Step 6.3 - Create retrieveResults function
 
    // Step 3.3 - Initialize the SDK
 
    // Step 5.4 - Add effect to handle redirect
 
    return (
        <div className="max-w-2xl mt-12 mx-auto px-8">
            <h1 className="text-3xl font-bold my-8">mDocs Online Verification Tutorial</h1>
            {/* Step 4.3 - Add request button */}
 
            {/* Step 5.5 - Render results */}
        </div>
    )
}

7. Run the project:

npm run dev

This will run the app and make it available at http://localhost:3000  (or the next available port if 3000 is already used).

8. Start an ngrok tunnel in a new terminal window:

ngrok http http://localhost:3000

Your terminal window should show the tunnel details:

9. Make note of the Forwarding value, you will use it in the next step.

Update the domain and redirect URI

With the tunneling service now active, update the MATTR VII verifier application configuration to include the domain and redirect URI details.

1. Expand the Credential Verification section in the left-hand navigation panel.

2. Select Applications.

3. Select the verifier application configuration you created in the previous step.

4. Update the Allowed domains text box to include the Forwarding URL from the ngrok tunnel, removing the https:// prefix.

5. Update the Redirect URIs text box to include the Forwarding URL from the ngrok tunnel.

6. Select the Update button to update the application configuration.

   The Forwarding URL is a temporary URL that will be used to test the web application. It will change every time you restart the ngrok tunnel, so you will need to repeat this step each time you restart the tunnel.

Initialize SDK

1. Create a new file named .env.local in the projects root folder and add the following code to add your tenant’s URL to the project’s variables:

   NEXT_PUBLIC_TENANT_URL=<YOUR_TENANT_URL>

   • NEXT_PUBLIC_TENANT_URL : Use your tenant_url.

2. Copy and paste the following code under the Step 3.2 - Add dependencies comment to add required dependencies to your web application:

   tsx

   import * as MATTRVerifierSDK from '@mattrglobal/verifier-sdk-web'
   import { useCallback, useEffect, useState } from 'react'

3. Copy and paste the following code under the Step 3.3 - Initialize the SDK comment to create a new function that will be used by your web application to initialize the SDK:

   tsx

   useEffect(() => {
       MATTRVerifierSDK.initialise({
           apiBaseUrl: process.env.NEXT_PUBLIC_TENANT_URL as string,
           applicationId: '0eaa8074-8cc4-41ec-9e42-072d36e2acb0'
       })
   }, [])

   The function calls the SDK’s initialise  function that makes the SDK methods available in your web application while defining the following parameters:

   • apiBaseUrl: This indicates to the Verifier Web SDK what MATTR VII tenant to interact with in order to verify presented mDocs. It is retrieved from the NEXT_PUBLIC_TENANT_URL project variable defined in step 1 above.
   • applicationId : This will be used by the MATTR VII tenant to identify verification requests from your web application. Replace with the id displayed on the Application detail screen of your created application configuration.

Create credential request

Now that you have a function and a UI in place, you need to define what the function does by creating a credential request. This request will define what information is requested from the user, and how to interact with the MATTR VII verifier tenant.

1. Copy and paste the following code under the Step 4.1 - Create requestCredential function comment to create a new requestCredentials function:

   tsx

   const requestCredentials = useCallback(async () => {
       const credentialQuery = {
           profile: MATTRVerifierSDK.OpenidPresentationCredentialProfileSupported.MOBILE,
           docType: 'org.iso.18013.5.1.mDL',
           nameSpaces: {
               'org.iso.18013.5.1': {
                   age_over_18: {},
                   given_name: {},
                   family_name: {},
                   portrait: {}
               }
           }
       } as MATTRVerifierSDK.CredentialQuery
    
       // Step 4.2 - Add credential request
   }, [])

   This function currently includes a credentialQuery variable that defines what information is requested from the user for verification:

   This example credential query will request the age_over_18, given_name, family_name and portrait claims from a credential of profile mobile and docType org.iso.18013.5.1.mDL, under the org.iso.18013.5.1 namespace. Presenting a credential with different names, docType or namespace will fail verification.

2. Copy and paste the following code under the Step 4.2 - Add credential request comment so that the new requestCredentials function calls the SDK’s requestCredentials function, passing the credentialQuery variable as a parameter:

   tsx

   const options: MATTRVerifierSDK.RequestCredentialsOptions = {
       credentialQuery: [credentialQuery],
       // Step 6.2 - Use challenge from backend
       challenge: MATTRVerifierSDK.utils.generateChallenge(),
       redirectUri: window.location.origin,
       crossDeviceCallback: {
           onComplete: (callbackResponse) => {
               // Step 5.2 - Retrieve cross-device verification results
           },
           onFailure: (error) => {
               if (error.type === 'Abort') {
                   alert('The request was aborted')
                   return
               }
               alert(`There was an error processing the request - ${error.message}`)
           }
       }
   }
    
   await MATTRVerifierSDK.requestCredentials(options)

   • options : This object defines the required parameters for calling the SDK’s requestCredentials function. It is passed as a parameter to the function when calling it.
   • credentialQuery : Defines what information is requested from the user for verification. This example uses the credential query created in the previous step.
   • challenge : Unique challenge generated by the SDK to identify this specific presentation session. You will use it in part 3 of the tutorial.
   • redirectUri : Indicates that the user will be redirected to the same web application screen when completing a same-device workflow. It can be any other path on your application domain, as long as it is handled by the application.
   • crossDeviceCallback : You will update this property later to configure how the web application handles the callback when a response is received as part of a cross-device workflow.

3. Copy and paste the following code under the Step 4.3 - Add request credentials button comment to create a new button that the user will use to interact with the web application:

   tsx

   <button
       onClick={requestCredentials}
       className="px-4 py-2 rounded border-2 border-black font-bold"
   >
       Request Credential
   </button>

   Once the user selects this button, the web application will trigger the verification workflow by calling the requestCredentials function created above:

   • This function uses calls the SDK’s requestCredentials method which starts a presentation session with the configured MATTR VII session.
   • Once a session is established, the MATTR VII verifier tenant will interact with the user’s wallet application to request and verify the details provided in the query.
   • When the verification process is complete, the MATTR VII verifier tenant will return the verification results to your web application.

Handle verification results

1. Copy and paste the following code under the Step 5.1 - Store results state comment to create a variable that will store the verification state:

   tsx

   const [results, setResults] = useState<MATTRVerifierSDK.PresentationSessionResult | null>(null)

2. Copy and paste the following code under the Step 5.2 - Retrieve cross-device verification results comment to retrieve verification results when they are available in cross-device workflows (onComplete of requestCredentials):

   tsx

   if ('result' in callbackResponse) {
       // Step 6.4 - Call retrieveResults function on cross-device callback
       setResults(callbackResponse.result as MATTRVerifierSDK.PresentationSessionResult)
   }

3. Copy and paste the following code under the Step 5.3 - Handle same-device redirect comment to create a new handleRedirect function:

   tsx

   const handleRedirect = useCallback(async () => {
       const result = await MATTRVerifierSDK.handleRedirectCallback()
    
       if (result.isErr()) {
           alert(`Error retrieving results: ${result.error.message}`)
           return
       }
    
       const presentationResult = result.value.result
       if (!('sessionId' in presentationResult) || 'error' in presentationResult) {
           alert('Something went wrong')
           return
       }
    
       // Step 6.5 - Call retrieveResults function on same-device redirect
       setResults(presentationResult as MATTRVerifierSDK.PresentationSessionResult)
   }, [])

   This function calls the SDK’s handleRedirectCallback  function, which returns the verification results as the user is redirected following a same-device presentation workflow. These results (result.value.result) are stored by the web application handleRedirect function in the presentationResult variable.

4. Copy and paste the following code under the Step 5.4 - Add effect to handle redirect comment to add an effect that calls the handleRedirect function when the web application is refreshed with a hash, indicating a redirect after completing a same-device presentation workflow:

   tsx

   useEffect(() => {
       if (window.location.hash) {
           handleRedirect()
       }
   }, [handleRedirect])

5. Copy and paste the following code under the Step 5.5 - Render results comment to retrieve different properties of the results object once it is available, and display them to the user as part of the interaction:

   tsx

   ;<h2 className="text-xl font-bold mt-8 mb-4">Results</h2>
   {
       !results && 'No results available'
   }
   {
       results && 'credentials' in results && (
           <div className="flex flex-col gap-2">
               <div className="flex flex-row">
                   <div className="w-1/3 font-bold">Verification Result</div>
                   <div className="w-2/3">
                       {results.credentials?.[0].verificationResult.verified
                           ? 'verified'
                           : 'not verified'}
                   </div>
               </div>
               <div className="flex flex-row">
                   <div className="w-1/3 font-bold">Valid Until</div>
                   <div className="w-2/3">{results.credentials?.[0].validityInfo.validUntil}</div>
               </div>
               <div className="flex flex-row">
                   <div className="w-1/3 font-bold">Issuer</div>
                   <div className="w-2/3">{results.credentials?.[0].issuerInfo.commonName}</div>
               </div>
               <div className="flex flex-row">
                   <div className="w-1/3 font-bold">Given Name</div>
                   <div className="w-2/3">
                       {(results.credentials?.[0].claims?.['org.iso.18013.5.1'].given_name
                           .value as string) ?? ''}
                   </div>
               </div>
               <div className="flex flex-row">
                   <div className="w-1/3 font-bold">Age over 18</div>
                   <div className="w-2/3">
                       {results.credentials?.[0].claims?.['org.iso.18013.5.1'].age_over_18.value
                           ? 'Yes'
                           : 'No'}
                   </div>
               </div>
           </div>
       )
   }
   {
       results && 'error' in results && (
           <div className="flex flex-row">
               <div className="w-1/3 font-bold">{results.error.type}</div>
               <div className="w-2/3">{results.error.message}</div>
           </div>
       )
   }

   In this example when verification is successful ("credentials" in results) the app retrieves and displays the following properties of the first credential (credentials?.[0]) of the results object:

   • verificationResult.verified : Indicates whether or not the mDoc was verified.
   • validityInfo.validUntil : Indicates the mDoc expiry date.
   • issuerInfo.commonName : Indicates the issuer’s name.
   • claims?.['org.iso.18013.5.1'].given_name : Indicates the holder’s given name.
   • claims?.['org.iso.18013.5.1'].age_over_18.value : Indicates whether or not the holder is over 18.

   When verification fails ("error" in results) the app retrieves and displays error details (error.type and error.message) from the results response.

Your web application will now continue the interaction based on the workflow type:

• For cross-device workflows, the web application will display the verification results in the desktop browser where the interaction started. The user can then continue the interaction on this desktop browser.
• For same-device workflows, the MATTR VII verifier tenant will redirect the user back to the web application in their mobile browser, where verification will be displayed. The user can then continue the interaction on this mobile browser.

Update verifier application configuration

The first thing you need to do is to make sure verification results are not returned directly to the web application’s front channel. This setting is part of your MATTR VII verifier application configuration.

1. Expand the Credential Verification section in the left-hand navigation panel.

2. Select Applications.

3. Select the verifier application configuration you created in the previous step.

4. Use the Verification results return method radio button to select Must be retrieved and validated by backend.

5. Select the Update button to update the application configuration.

   This setting is only available when the application type is set to Web.

Add your MATTR VII access credentials

Your backend will need to make a request to a protected MATTR VII endpoint to retrieve the verification results. To enable this, you must provide it with your MATTR VII tenant access credentials.

1. Add the following code to your .env.local file to add your MATTR VII tenant access credentials:

   MATTR_CLIENT_ID=ZAGvD********************************
   MATTR_CLIENT_SECRET=uc8NM****************************************

• MATTR_CLIENT_ID : Replace with the tenant’s client_id value.
• MATTR_CLIENT_SECRET : Replace with the tenant’s client_secret value.

Create a session and associate a challenge

The web application backend needs to generate a unique challenge in the context of an existing user session. In a typical application, the user would likely already interact with the application inside an active session, and often that session is tracked using a cookie. In this tutorial you are mimicking this by setting a random value as the user session ID.

You are also creating a random challenge and storing it inside a cookie to ensure that the presentation results you are retrieving belong to the user in the current user session.

1. Create a new file at src/app/api/request/route.ts with the following content:

import { cookies } from 'next/headers'
 
export async function POST(_request: Request) {
    const sessionId = crypto.randomUUID()
    const challenge = crypto.randomUUID()
 
    const cookieStore = await cookies()
    cookieStore.set('session_id', sessionId, { httpOnly: true, secure: true, sameSite: true })
    cookieStore.set('challenge', challenge, { httpOnly: true, secure: true, sameSite: true })
 
    return Response.json({ challenge }, { status: 201 })
}

While it’s not strictly necessary to keep the challenge secret, you might want to only use a single encrypted session cookie to not leak any information about your session management.

If you use a database to store the sessions state, you could use that database to store the challenge against the user session.

Retrieve verification results

Next you need to create an API route that will make a request to the MATTR VII verifier tenant and retrieve the results of a specific presentation session based on its ID.

1. Create a new file at src/app/api/results/[id]/route.ts with the following content:

   ts

   import { cookies } from 'next/headers'
    
   async function getToken() {
       const response = await fetch('https://auth.au01.mattr.global/oauth/token', {
           method: 'POST',
           headers: {
               'content-type': 'application/json'
           },
           body: JSON.stringify({
               client_id: process.env.MATTR_CLIENT_ID,
               client_secret: process.env.MATTR_CLIENT_SECRET,
               audience: process.env.NEXT_PUBLIC_TENANT_URL,
               grant_type: 'client_credentials'
           })
       })
    
       const { access_token } = await response.json()
       return access_token
   }
    
   export async function GET(_: Request, { params }: { params: Promise<{ id: string }> }) {
       const id = (await params).id
       const cookiesStore = await cookies()
    
       if (!cookiesStore.get('session_id')) {
           return Response.json({ error: 'No valid session for user' }, { status: 401 })
       }
    
       const response = await fetch(
           `${process.env.NEXT_PUBLIC_TENANT_URL}/v2/presentations/sessions/${id}/result`,
           {
               headers: {
                   authorization: `Bearer ${await getToken()}`
               }
           }
       )
    
       const results = await response.json()
    
       if (results.challenge !== cookiesStore.get('challenge')?.value) {
           return Response.json({ error: 'Challenge does not match' })
       }
    
       return Response.json({ results })
   }

   The getToken function first uses project variables to retrieve a MATTR VII access token, as the results are retrieved from a protected endpoint.

   The route must be called with a dynamic id route parameter. This is the unique identifier of the presentation session. It is used in the authenticated request to the /v2/presentations/sessions/${id}/result endpoint to retrieve the corresponding verification results.

   Your backend must then validate the returned results. The exact implementation would depend on your user session management, but you should always ensure that:

   • The request to retrieve the results comes from an active user session (as per its session_id).
   • The challenge included in the response from the MATTR VII tenant matches the challenge you have stored for that active user session.

Adjust front channel to retrieve results via backend

Now that the backend is configured to retrieve the verification results, you need to adjust the front channel web application so that it can retrieve these results from the backend.

1. Copy and paste the following code under the Step 6.1 - Create createRequest function comment.

   tsx

   async function createRequest() {
       const response = await fetch('/api/request', { method: 'POST' })
       const { challenge } = await response.json()
       return challenge
   }

2. Replace the challenge assignment under the Step 6.2 - Use challenge from backend comment with the following code to call the createRequest function to generate a challenge:

   tsx

         challenge: await createRequest(),

3. Add the following code under the Step 6.3 - Create retrieveResults function comment to create a new function that retrieves the verification results:

   tsx

   const retrieveResults = useCallback(async (id: string) => {
       const response = await fetch(`api/results/${id}`)
       const { results } = await response.json()
       setResults(results as MATTRVerifierSDK.PresentationSessionResult)
   }, [])

   This function uses the API route created above to retrieve the verification results and assign them to the presentationResults variable.

4. Replace the setResults call under the Step 6.4 - Call retrieveResults function on cross-device callback with the following code to call the new retrieveResults function in the callback of a cross-device workflow:

   tsx

   retrieveResults(callbackResponse.result.sessionId)

5. Replace the setResults call under the Step 6.5 - Call retrieveResults function on same-device redirect with the following code to call the new retrieveResults function when the user is redirected to the app following a same-device workflow:

   tsx

   retrieveResults(presentationResult.sessionId)