Get started using App Check with SafetyNet on Android

This page shows you how to enable App Check in an Android app, using the built-in SafetyNet provider. When you enable App Check, you help ensure that only your app can access your project's Firebase resources. See an Overview of this feature.

If you want to use App Check with your own custom provider, see Implement a custom App Check provider.

1. Set up your Firebase project

1. Add Firebase to your Android project if you haven’t already done so.

2. Register your apps to use App Check with the SafetyNet provider in the App Check section of the Firebase console. You will need to provide the SHA-256 fingerprint of your app's signing certificate.

   You usually need to register all of your project's apps, because once you enable enforcement for a Firebase product, only registered apps will be able to access the product's backend resources.

3. Optional: In the app registration settings, set a custom time-to-live (TTL) for App Check tokens issued by the provider. You can set the TTL to any value between 30 minutes and 7 days. When changing this value, be aware of the following tradeoffs:

   • Security: Shorter TTLs provide stronger security, because it reduces the window in which a leaked or intercepted token can be abused by an attacker.
   • Performance: Shorter TTLs mean your app will perform attestation more frequently. Because the app attestation process adds latency to network requests every time it's performed, a short TTL can impact the performance of your app.
   • Quota and cost: Shorter TTLs and frequent re-attestation deplete your quota faster, and for paid services, potentially cost more. See Quotas & limits.

   The default TTL of 1 hour is reasonable for most apps. Note that the App Check library refreshes tokens at approximately half the TTL duration.

2. Add the App Check library to your app

In your module (app-level) Gradle file (usually app/build.gradle), declare the dependency for the App Check Android library:

dependencies {
    implementation 'com.google.firebase:firebase-appcheck-safetynet:16.0.2'
}

dependencies {
    implementation 'com.google.firebase:firebase-appcheck-safetynet:16.0.2'
}

3. Initialize App Check

Add the following initialization code to your app so that it runs before you use any other Firebase SDKs:

FirebaseApp.initializeApp(/*context=*/ this);
FirebaseAppCheck firebaseAppCheck = FirebaseAppCheck.getInstance();
firebaseAppCheck.installAppCheckProviderFactory(
        SafetyNetAppCheckProviderFactory.getInstance());

FirebaseApp.initializeApp(/*context=*/this)
val firebaseAppCheck = FirebaseAppCheck.getInstance()
firebaseAppCheck.installAppCheckProviderFactory(
    SafetyNetAppCheckProviderFactory.getInstance()
)

Next steps

Once the App Check library is installed in your app, start distributing the updated app to your users.

The updated client app will begin sending App Check tokens along with every request it makes to Firebase, but Firebase products will not require the tokens to be valid until you enable enforcement in the App Check section of the Firebase console.

Monitor metrics and enable enforcement

Before you enable enforcement, however, you should make sure that doing so won't disrupt your existing legitimate users. On the other hand, if you're seeing suspicious use of your app resources, you might want to enable enforcement sooner.

To help make this decision, you can look at App Check metrics for the services you use:

• Monitor App Check request metrics for Realtime Database, Cloud Firestore, and Cloud Storage.
• Monitor App Check request metrics for Cloud Functions.

Enable App Check enforcement

When you understand how App Check will affect your users and you're ready to proceed, you can enable App Check enforcement:

• Enable App Check enforcement for Realtime Database, Cloud Firestore, and Cloud Storage.
• Enable App Check enforcement for Cloud Functions.

Use App Check in debug environments

If, after you have registered your app for App Check, you want to run your app in an environment that App Check would normally not classify as valid, such as an emulator during development, or from a continuous integration (CI) environment, you can create a debug build of your app that uses the App Check debug provider instead of a real attestation provider.

See Use App Check with the debug provider on Android.