public class Biometrics

Entry point for biometric authentication (Touch ID, Face ID, fingerprint, Android BiometricPrompt). Obtain the platform implementation via getInstance(); the returned subclass is owned by the active port.

A typical unlock flow:

Biometrics b = Biometrics.getInstance();
if (!b.canAuthenticate()) {
    // Fall back to password
    return;
}
b.authenticate("Unlock your account").onResult((success, err) -> {
    if (err != null) {
        BiometricError code = ((BiometricException) err).getError();
        // branch on code
    } else {
        // success
    }
});

authenticate(AuthenticationOptions) returns an AsyncResource whose failure path completes with a BiometricException so callers can branch on the typed BiometricError.

Platform support

• iOS – uses LocalAuthentication.framework (LAContext). Touch ID and Face ID on supported devices. Add the ios.NSFaceIDUsageDescription build hint when targeting Face ID hardware.
• Android – uses BiometricPrompt on API 29+ (Android 10) and FingerprintManagerCompat on API 23-28. Fingerprint, face, and iris modalities are reported per PackageManager features. The legacy path goes through the support library rather than android.hardware.fingerprint directly, which Android removed in API 37, so an app compiled against any platform still authenticates on an API 23-28 device.
• JavaSE simulator – behaves as a real device with no enrolled biometrics by default. The Simulate -> Biometric Simulation submenu in the simulator lets you toggle hardware availability, enrolled modalities, and the outcome of the next authenticate(String) call.
• All other platforms (desktop deploy, JavaScript, …) – this base class is returned as-is and acts as a non-supporting fallback: isSupported() / canAuthenticate() return false and authenticate(String) completes with BiometricError.NOT_AVAILABLE. Application code does not need platform if statements – always gate biometrics on canAuthenticate() before invoking the prompt.