firebase-auth: add App Check token exchange for SafetyNet attestation#3602
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Meet-hybrid wants to merge 1 commit into
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firebase-auth: add App Check token exchange for SafetyNet attestation#3602Meet-hybrid wants to merge 1 commit into
Meet-hybrid wants to merge 1 commit into
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Add AppCheckTokenProvider that performs SafetyNet attestation via DroidGuard and exchanges the JWS for a Firebase App Check token at firebaseappcheck.googleapis.com. Inject the token as the X-Firebase-AppCheck header in all Identity Toolkit API requests. Previously, IdentityToolkitClient sent requests without App Check headers, causing UNAUTHENTICATED rejections from Firebase projects with App Check enforcement enabled (e.g. com.ridedott.rider). Includes EXTRA_FIREBASE_APP_ID and EXTRA_PROJECT_NUMBER constants for the AIDL service binding to provide the required identifiers.
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This PR addresses an issue where Firebase Auth requests in GmsCore were being rejected with UNAUTHENTICATED / MISSING_APP_CHECK_TOKEN errors because they lacked the required X-Firebase-AppCheck header.
Changes Made
Constants.java: Added EXTRA_FIREBASE_APP_ID and EXTRA_PROJECT_NUMBER.
AppCheckTokenProvider.kt (New): Implemented token exchange and caching, utilizing SafetyNet attestation (DroidGuard + androidcheck API).
IdentityToolkitClient.kt: Updated to accept AppCheckTokenProvider, refresh the token before requests, and inject the X-Firebase-AppCheck header.
FirebaseAuthService.kt: Modified to parse new extras and pass them to FirebaseAuthServiceImpl.
firebase-auth/core/build.gradle: Added necessary dependencies: play-services-safetynet-core, play-services-droidguard, play-services-droidguard-core, and play-services-tasks-ktx.
Architecture
The AppCheckTokenProvider operates within FirebaseAuthServiceImpl. It manages caching, performs SafetyNet attestation, exchanges JWS for an App Check token via firebaseappcheck.googleapis.com, and injects the required header. If SafetyNet/DroidGuard is disabled or identifiers are missing, the implementation falls back gracefully by returning null.