Biometric authentication in Android Kotlin - Build, Publish & Deploy

Build & Publish - Biometric authentication

Performance Impact

Using biometric authentication has minimal impact on frame rate and memory because it relies on the device's secure hardware and system services. The biometric prompt is handled by the OS, so your app's UI remains smooth, targeting 60fps or higher. Battery usage is low since biometric checks are quick and hardware-accelerated.

Optimization Tips

To keep your app responsive during biometric authentication, avoid heavy processing on the main thread. Use asynchronous callbacks for authentication results. Cache authentication state securely to reduce repeated prompts. Also, handle fallback methods gracefully to avoid blocking UI.

App Size and Startup Time

Integrating biometric authentication uses Android's built-in BiometricPrompt API, so it adds no extra library size to your app bundle. This keeps your APK or AAB size small and does not affect startup time. Avoid adding third-party biometric libraries to keep the app lightweight.

iOS vs Android Differences

On Android, biometric authentication uses the BiometricPrompt API, supporting fingerprint, face, and iris depending on device. On iOS, Face ID and Touch ID are accessed via the LocalAuthentication framework. Both platforms handle UI prompts natively, but Android requires checking hardware availability and permissions explicitly. iOS handles permissions automatically.

Store Review Guidelines

• Privacy: Clearly explain why biometric data is used in your app's privacy policy.
• Security: Do not store biometric data yourself; use system APIs only.
• User Consent: Ensure users opt-in before biometric authentication.
• Fallback: Provide alternative login methods if biometrics fail or are unavailable.
• Google Play: Follow Google Play's User Data policy regarding biometric usage.
• Apple App Store: If using Face ID/Touch ID on iOS, comply with Apple's Human Interface Guidelines.

Self-Check Question

Your app takes 5 seconds to load the biometric authentication screen. What's likely wrong?

• You might be performing heavy work on the main thread before showing the biometric prompt.
• Biometric hardware availability checks or permission requests are blocking UI.
• Using a third-party biometric library that adds startup overhead.

Key Result

Biometric authentication uses native OS APIs with minimal performance impact and no added app size. Optimize by handling authentication asynchronously and providing fallback methods. Follow privacy and security guidelines for smooth app store approval.