How to build an Android application that can present a credential via the DC API

Initialize the SDK with support for the DC API enabled

When you initialize the SDK with the DC API feature enabled, the SDK automatically:

• Registers your application as a credential provider with the Android operating system
• Registers all claimed credentials with the Digital Credentials Manager (DCM)
• Handles incoming presentation requests

Adjust your SDK initialization code to enable DC API support by setting the enabled flag to true in the DcmConfiguration:

MobileCredentialHolder.getInstance().initialize(
    context, 
    dcmConfiguration = DcmConfiguration(enabled = true)
)

Handle verifier authentication results (optional)

The SDK provides an API to detect if the Verifier can be trusted. This is an optional step as the SDK will handle the presentation flow and user authentication with the operating system in the background without any involvement from the app. However, if your application has specific requirements around when verifier authentication should be required, you can use this API to enforce that.

Perform the following steps to implement verifier authentication in your application:

1. Add the following intent filter in your application's AndroidManifest.xml file to allow it to receive the verifier authentication result from the SDK:

<intent-filter>
    <action android:name="global.mattr.credentialmanager.action.CONFIRMATION" />
    <category android:name="android.intent.category.DEFAULT" />
</intent-filter>

<intent-filter>
    <action android:name="global.mattr.credentialmanager.action.ERROR" />
    <category android:name="android.intent.category.DEFAULT" />
</intent-filter>

These are both optional intent filters. The first one allows your application to receive the verifier authentication result when the verifier is trusted or untrusted but signed. The second one allows your application to receive a callback when an error occurs during the authentication process. If you choose not to implement these intent filters, the SDK will still handle the presentation flow and user authentication with the operating system in the background without any involvement from your app.

2. Handle the incoming intents in the corresponding activity onCreate method:

val verifierAuthenticationResult: VerifierAuthenticationResult? = when (intent.action) {
    "global.mattr.credentialmanager.action.CONFIRMATION" -> {
        IntentCompat.getParcelableExtra(
            intent,
            "global.mattr.credentialmanager.extra.verifier_authentication_result",
            VerifierAuthenticationResult::class.java
        )
    }

    "global.mattr.credentialmanager.action.ERROR" -> null

    else -> {
        finish()
        return
    }
}

This code example retrieves the verifier authentication result from the incoming intent when the action is global.mattr.credentialmanager.action.CONFIRMATION. If the action is global.mattr.credentialmanager.action.ERROR, it sets the result to null, indicating that an error occurred during the authentication process.

3. Handle the result of the Verifier authentication based on your requirements. For example:

when (verifierAuthenticationResult) {
    is VerifierAuthenticationResult.Trusted -> {
        // If this reader is trusted, just return success
        setResult(RESULT_OK)
        finish()
        return
    }

    is VerifierAuthenticationResult.Untrusted, is VerifierAuthenticationResult.Unsigned -> {
        // Require user confirmation and set the activity result based on the 
        // user's decision in the confirmation screen.
    }

    null -> {
        // An error occurred during the authentication process. Show an error message.
        // ...
        setResult(RESULT_CANCELED)
        finish()
        return
    }
}

In this example, if the verifier is trusted, the application simply returns a successful result. If the verifier is untrusted or unsigned, the application can prompt the user for confirmation and set the activity result based on the user's decision.

Test the application

Let's test that the application is working as expected in both workflows.

Same-device workflow

1. Use a browser on your testing mobile device to navigate to the MATTR Labs remote presentation testing tool.
2. Select Digital Credentials API from the Select Experience list.
3. Select Request credentials.
4. Confirm interacting with the verifier on your mobile device when prompted by the operating system (this might look different based on the device and operating system version).
5. Select the credential you wish to send to the verifier from the list of credentials suggested by the operating system.
6. Send the response.
7. The UI prompt will close, and you should see a successful verification indication in the browser where you initiated the request.

Cross-device workflow

1. Use a desktop browser to navigate to the MATTR Labs remote presentation testing tool.
2. Select Digital Credentials API from the Select Experience list.
3. Select Request credentials.
4. Open the camera on your testing device and scan the QR code.
5. Confirm interacting with the verifier on your mobile device when prompted by the operating system (this might look different based on the device and operating system version).
6. Select the credential you wish to send to the verifier from the list of available credentials suggested by the operating system.
7. Send the response.
8. The UI prompt will close.
9. Back on your desktop browser, you should see a successful verification indication.