The Android Arsenal – Fingerprint

PLEASE NOTE:

If your project has minSDK 23 and should support only basic Fingerprint Authorization on most devices – take a look first at the AndroidX’s Biometric .

If you still need advanced Biometric authentication use Fingerpint, Face or Iris on the wide range of devices – see doc below.

Introduction

What is BiometricPrompt API?

This is a new API that declares that the system takes care of a unified way to use different biometric identification methods – fingerprint, face, iris, etc., as well as a unified way to display the UI on all devices.

To learn more, read BiometricPrompt Reference in Android Developers site.

Unfortunately, this simplification hides a number of problems.

• On Android 9, there is no way to simply get information about whether there is available biometric hardware and whether biometric data is enrolled. Android 10 provides BiometricManager that partially solves this problem.
• Some manufacturers have removed/do not display the biometric UI
• Biometric Auth solutions like Samsung Pass SDK or Meizu Fingerprint need to implement separately
• No way to identify what types of biometric auth available on the device.

How to use BiometricPromptCompat in old devices?

BiometricPromptCompat is designed to be compatible with the largest number of Android devices. Its interface is very close to the original BiometricPrompt. Minimal supported SDK – Android 4.1 JellyBean (API 16)

Key features

• Unified UI for all devices – starts from Android 4.1 and to Android 11
• Contains fix for devices WITHOUT system BiometricPrompt UI (like LG G8 or OnePlus 6T)
• Dark/Light themes supported; Also you able to get the background color of the current Biometric dialog
• Auth in Split-Screen Mode supported
• Wide range of supported biometrics

Supported types of biometric authentication

Setup

Include library in your app:

    repositories {
         maven { url 'https://developer.huawei.com/repo/' }
         maven { url "https://dl.bintray.com/tencent-soter/maven/" }
         maven { url "https://pkgs.dev.azure.com/MicrosoftDeviceSDK/DuoSDK-Public/_packaging/Duo-SDK-Feed/maven/v1" }
    }


dependencies {
     implementation 'dev.skomlach:biometric:X.X.X'
}

Usage

• At first, you need to create the BiometricPromptCompat

BiometricPromptCompat.Builder builder =
 new BiometricPromptCompat.Builder(getActivity())
 .setTitle("Biometric demo")
 .setNegativeButton("Cancel", null);  
BiometricPromptCompat biometricPromptCompat = builder.build();  

Please note: Methods builder.setTitle() and builder.setNegativeButton() are mandatory.

• You also able to specify the desired implementation use the next builder:

BiometricPromptCompat.Builder builder =
 new BiometricPromptCompat.Builder(BiometricApi, getActivity());     

BiometricApi:

BiometricApi.AUTO – the library will peek at the best-matched API (default)

BiometricApi.LEGACY_API – forced usage of legacy biometric APIs like Fingerprint or FaceUnlock, and custom UI

BiometricApi. BIOMETRIC_API – forced usage of new BiometricPrompt API

BiometricPromptCompat:

void authenticate(BiometricPromptCompat.Result resultCallback) – start biometric auth workflow

void cancelAuthenticate() – cancel active biometric auth workflow

boolean cancelAuthenticateBecauseOnPause() – Useful if you need to allow biometric auth in Split-Screen mode; Recommended to call this method in onResume() and use returned value to avoid biometric auth restart. Returns false and keep biometric auth on display if the app in Split-Screen mode, returns true and cancel active biometric auth otherwise

@ColorRes int getDialogMainColor() – returns dialog background color

boolean hasEnrolled() – returns true if any biometric enrolled

boolean isBiometricSensorPermanentlyLocked() – returns true if biometric permanently locked; Device lock-unlock or reboot required from the user

boolean isHardwareDetected() – returns true if any biometric hardware available

boolean isLockOut() – returns true if biometric temporarily locked; Usually need to wait for 30 seconds and the system will reset this lock

boolean isNewBiometricApi() – returns true if BiometricPrompt API used

void openSettings(Activity) – Attempting to open the “Enroll biometric” settings screen

BiometricPromptCompat.Result

void onSucceeded() – User successfully authenticated

void onCanceled() – Biometric authentification was canceled

void onFailed(AuthenticationFailureReason reason) – Error happens, see details in AuthenticationFailureReason

void onUIShown() – Biometric UI on display

I have a device that can be unlocked using Fingerprint/Face/Iris and(or) I can use this biometric type in pre-installed apps. But it doesn’t work on 3rd party apps. Can you help?

Yes, this is unfortunately happens very often. Many functions demanded by the market are often implemented by device manufacturers before the same API appears in the official Android SDK.

In short: The device manufacturer has implemented biometric authentication via fingerprint/face/iris, but “forgot” to provide access to this implementation for third-party developers. Therefore, preinstalled (system) applications developed by the device manufacturer can use biometrics, while banking applications, password managers, and other third-party applications cannot.

Full answer: It all depends on the specific case. I have come across several options that can be divided into several groups.

1. We know how the “Manager” defined and can add “dummy manager” into the biometric-api module, for example MiuiFaceManagerImpl. Unfortunately, this approach is not always possible to use.

First, starting with Android 9 appears restrictions on the use of non-public APIs. This limitation can be circumvented, BUT…

Secondly – anyway, the manager considered here uses system permissions, and as a result, a SecurityException will be thrown when we tried to get “Manager” instance.

2. We know how the “Manager” defined and can add “dummy manager” into the biometric-api module, like FaceID on EMUI 8.0 , EMUI 8.1 or EMUI 9.0 , and even able to get the “manager” instance. In this case, we will face the situation when working, for the first look, API, will not work in 3rd party apps properly.
3. Biometric auth implemented in the system com.android.keyguard package. For example, Meizu uses Face++ solution. Dependence on implementation, exists a chance to bind to the service as we do for FaceUnlock

Anyway, research and testing required for each case, so feel free to create issues or contact directly with me.

TODO

• Simplify setup
• Add more devices/manufacturers
• Check for the way to start BiometricAuth with specified BiometricType
• Cleanup project and README
• Migrate to Kotlin

Contact author

Telegram: @SergeyKomlach

Twitter: @SergejKomlach

License

Apache License 2.0

Buy me a beer, if you wish.