Biometric login

Overview
Biometric login is supported for the following operating systems:
iOS 11.3 or higher
Android 6.0 (API 23) or higher
Authgear supports enabling biometric login in the native mobile application. You will need to
1.Enable biometric login in your application via the portal.
2.In the mobile app, use the mobile SDK to enable biometric login for your users.
A pair of cryptographic keys will be generated upon registering biometric login. The private key will be stored securely in the device (using Keystore in Android and Keychain in iOS), while the public key is stored in the Authgear server. To authenticate the user, fingerprint or face is presented to unlock the private key, and a digital signed message is sent to the server to proof the authenticity of the user.
Sounds overwhelming? Authgear's magic handle all these for you. Follow this guide to enable biometric login in your app with a few lines of code.
Enable biometric login in your application
Portal
authgear.yaml
1.In the portal, go to "Biometric Authentication".
2.Turn on "Enable biometric authentication".
3.Click "Save".
authentication:
  identities:
    ...
    # Add biometric along with the other enabled identities
    - biometric
identity:
  biometric:
    # Enable listing biometric login in user setting page, default false
    list_enabled: true
Enable biometric login in mobile SDK
In the following section, we will show you how to use biometric login in the SDK. In the SDK code snippet, authgear is referring to the configured Authgear container.
Biometric options
In the SDKs, a set of biometric options is required to check the support or enable biometric on the device.
iOS
There are two options on iOS:
localizedReason is the message string the user will see when FaceID or TouchID is presented
constraint is an enum that constraint the access of key stored under different conditions:
biometryAny: The key is still accessible by Touch ID if fingers are added or removed, or by Face ID if the user is re-enrolled
BiometricCurrentSet: The key is invalidated if fingers are added or removed for Touch ID, or if the user re-enrolls for Face ID
See reference in Apple Developers Doc on biometryAny and biometryCurrentSet.
Android
There are 6 options on Android:
title is the Title of the biometric dialog presented to the users
subtitle is the subtitle of the biometric dialog presented to the users
description is the description of the biometric dialog presented to the users
negativeButtonText is what the dismiss button says in the biometric dialog
constraint is an array defines the requirement of security level, which can be BIOMETRIC_STRONG, BIOMETRIC_WEAK, DEVICE_CREDENTIAL. See reference in Android developers documentation on BiometricManager.Authenticators``
invalidatedByBiometricEnrollment is a boolean that controls if the key pair will be invalidated if a new biometric is enrolled, or when all existing biometrics are deleted. See reference in Android developers documentation on KeyGenParameterSpec.Builder.
Code examples
Check support
Always check if the current device supports biometric login before calling any biometric API, including before enabling biometric login and before using biometric to login.
iOS
Android
React Native
Flutter
Xamarin
// check if current device supports biometric login
var supported = false
do {
    try authgear.checkBiometricSupported()
    supported = true
} catch {}
​
if supported {
    // biometric login is supported
}
boolean supported = false;
try {
    // biometric login is supported SDK_INT >= 23 (Marshmallow)
    if (Build.VERSION.SDK_INT >= 23) {
        // check if current device supports biometric login
        authgear.checkBiometricSupported(
                this.getApplication(),
                ALLOWED
        );
        supported = true;
    }
} catch (Exception e) {}
if (supported) {
    // biometric login is supported
}
// We will need the options for the other biometric api
const biometricOptions = {
  ios: {
    localizedReason: 'Use biometric to authenticate',
    constraint: 'biometryCurrentSet' as const,
  },
  android: {
    title: 'Biometric Authentication',
    subtitle: 'Biometric authentication',
    description: 'Use biometric to authenticate',
    negativeButtonText: 'Cancel',
    constraint: ['BIOMETRIC_STRONG' as const],
    invalidatedByBiometricEnrollment: true,
  },
};
// check if current device supports biometric login
authgear
    .checkBiometricSupported(biometricOptions)
    .then(() => {
        // biometric login is supported
    })
    .catch(() => {
        // biometric login is not supported
    });
// We will need the options for the other biometric api
final ios = BiometricOptionsIOS(
    localizedReason: "Use biometric to authenticate",
    constraint: BiometricAccessConstraintIOS.biometryAny,
);
final android = BiometricOptionsAndroid(
    title: "Biometric Authentication",
    subtitle: "Biometric authentication",
    description: "Use biometric to authenticate",
    negativeButtonText: "Cancel",
    constraint: [BiometricAccessConstraintAndroid.biometricStrong],
    invalidatedByBiometricEnrollment: false,
);
​
try {
    // check if current device supports biometric login
    await authgear.checkBiometricSupported(ios: ios, android: android);
    // biometric login is supported
} catch (e) {
    // biometric login is not supported
}
// We will need the options for the other biometric api
var ios = new BiometricOptionsIos
{
    LocalizedReason = "Use biometric to authenticate",
    AccessConstraint = BiometricAccessConstraintIos.BiometricAny,
};
var android = new BiometricOptionsAndroid
{
    Title = "Biometric Authentication",
    Subtitle = "Biometric authentication",
    Description = "Use biometric to authenticate",
    NegativeButtonText = "Cancel",
    AccessConstraint = BiometricAccessConstraintAndroid.BiometricOnly,
    InvalidatedByBiometricEnrollment = false,
};
var biometricOptions = new BiometricOptions
{
    Ios = ios, 
    Android = android
};
try
{
    // check if current device supports biometric login
    authgear.EnsureBiometricIsSupported(biometricOptions);
    // biometric login is supported
}
catch
{
    // biometric login is not supported
}
Enable biometric login
Enable biometric login for logged in user
iOS
Android
React Native
Flutter
Xamarin
// provide localizedReason for requesting authentication
// which displays in the authentication dialog presented to the user
authgear.enableBiometric(
    localizedReason: "REPLACE_WITH_LOCALIZED_REASON",
    constraint: .biometryCurrentSet
) { result in
    if case let .failure(error) = result {
        // failed to enable biometric with error
    } else {
        // enabled biometric successfully
    }
}
// We will need the options for the other biometric api
BiometricOptions biometricOptions = new BiometricOptions(
    activity, // FragmentActivity
    "Biometric authentication", // title
    "Biometric authentication", // subtitle
    "Use biometric to authenticate", // description
    "Cancel", // negativeButtonText
    ALLOWED, // allowedAuthenticators
    true // invalidatedByBiometricEnrollment
);
authgear.enableBiometric(
    biometricOptions,
    new OnEnableBiometricListener() {
        @Override
        public void onEnabled() {
            // enabled biometric login successfully
        }
​
        @Override
        public void onFailed(Throwable throwable) {
            // failed to enable biometric with error
        }
    }
);
authgear
    .enableBiometric(biometricOptions)
    .then(() => {
        // enabled biometric login successfully
    })
    .catch((err) => {
        // failed to enable biometric with error
    });
try {
    await authgear.enableBiometric(ios: ios, android: android);
    // enabled biometric login successfully
} catch (e) {
    // failed to enable biometric with error
}
try
{
    await authgear.EnableBiometricAsync(biometricOptions);
    // enabled biometric login successfully
}
catch
{
    // failed to enable biometric with error
}
Check if biometric has been enabled before
Before asking the user to log in with biometric, Check if biometric login has been enabled on the current device. I.e. Is the key pair exist on the device (Keystore in Android and Keychain in iOS).
This method will still return true even if all the fingerprint and facial data has been removed from the device. Before this method, you should use the "checkBiometricSupported" to check if biometry is supported in the device level.
iOS
Android
React Native
Flutter
Xamarin
var enabled = (try? authgear.isBiometricEnabled()) ?? false
boolean enabled = false;
try {
    enabled = authgear.isBiometricEnabled();
} catch (Exception e) {}
authgear
    .isBiometricEnabled()
    .then((enabled) => {
        // show if biometric login is enabled
    })
    .catch(() => {
        // failed to check the enabled status
    });
try {
    final enabled = await authgear.isBiometricEnabled();
    // show if biometric login is enabled
} catch (e) {
    // failed to check the enabled status
}
try
{
    var enabled = await authgear.GetIsBiometricEnabledAsync();
    // show if biometric login is enabled
}
catch
{
    // failed to check the enabled status
}
Login with biometric credentials
If biometric is supported and enabled, you can use the Authenticate Biometric method to log the user in. If the key pair is invalidated due to changes in the biometry settings, e.g added fingerprint or re-enrolled face data, the biometricPrivateKeyNotFound will be thrown. You should handle the error by the Disable Biometric method, and ask the user to register biometric login again.
iOS
Android
React Native
Flutter
Xamrin
authgear.authenticateBiometric { result in
    switch result {
        case let .success(authResult):
            let userInfo = authResult.userInfo
            // logged in successfully
        case let .failure(error):
            // failed to login
        }
}
authgear.authenticateBiometric(
    biometricOptions,
    new OnAuthenticateBiometricListener() {
        @Override
        public void onAuthenticated(UserInfo userInfo) {
            // logged in successfully
        }
​
        @Override
        public void onAuthenticationFailed(Throwable throwable) {
            // failed to login
        }
    }
);
authgear
    .authenticateBiometric(biometricOptions)
    .then(({userInfo}) => {
        // logged in successfully
    })
    .catch((e) => {
        // failed to login
    });
try {
    final userInfo = await authgear.authenticateBiometric(ios: ios, android: android);
    // logged in successfully
} catch (e) {
    // failed to login
}
try
{
    var userInfo = await authgear.AuthenticateBiometricAsync(biometricOptions);
    // logged in successfully
}
catch
{
    // failed to login
}
Disable biometric login on the current device
iOS
Android
React Native
Flutter
Xamarin
do {
    try authgear.disableBiometric()
    // disabled biometric login successfully
} catch {
    // failed to disable biometric login
}
try {
    authgear.disableBiometric();
    // disabled biometric login successfully
} catch (Exception e) {
    // failed to disable biometric login
}
authgear
    .disableBiometric()
    .then(() => {
        // disabled biometric login successfully
    })
    .catch((err) => {
        // failed to disable biometric login
    });
try {
    await authgear.disableBiometric();
    // disabled biometric login successfully
} catch (e) {
    // failed to disable biometric login
}
try
{
    await authgear.DisableBiometricAsync();
    // disabled biometric login successfully
}
catch
{
    // failed to disable biometric login
}
Error handling
In all methods related to biometric, the SDK may throw the following errors that describe the status of the biometry enrollment or the key pair stored on the device.
iOS
Android
React Native
Flutter
Xamarin
if let authgearError = error as? AuthgearError {
    switch authgearError {
    case .cancel:
        // user cancel
    case .biometricPrivateKeyNotFound:
        // biometric info has changed. e.g. Touch ID or Face ID has changed.
        // user have to set up biometric authentication again
    case .biometricNotSupportedOrPermissionDenied:
        // user has denied the permission of using Face ID
    case .biometricNoPasscode:
        // device does not have passcode set up
    case .biometricNoEnrollment:
        // device does not have Face ID or Touch ID set up
    case .biometricLockout:
        // the biometric is locked out due to too many failed attempts
    default:
        // other error
        // you may consider showing a generic error message to the user
    }
}
import com.oursky.authgear.BiometricLockoutException;
import com.oursky.authgear.BiometricNoEnrollmentException;
import com.oursky.authgear.BiometricNoPasscodeException;
import com.oursky.authgear.BiometricNotSupportedOrPermissionDeniedException;
import com.oursky.authgear.BiometricPrivateKeyNotFoundException;
import com.oursky.authgear.CancelException;
​
​
if (e instanceof CancelException) {
    // user cancel
} else if (e instanceof BiometricPrivateKeyNotFoundException) {
    // biometric info has changed
    // user have to set up biometric authentication again
} else if (e instanceof BiometricNoEnrollmentException) {
    // device does not have biometric set up
} else if (e instanceof BiometricNotSupportedOrPermissionDeniedException) {
    // biometric is not supported in the current device
    // or user has denied the permission of using biometric
} else if (e instanceof BiometricNoPasscodeException) {
    // device does not have unlock credential set up
} else if (e instanceof BiometricLockoutException) {
    // the biometric is locked out due to too many failed attempts
} else {
    // other error
    // you may consider showing a generic error message to the user
}
import {
    CancelError,
    BiometricPrivateKeyNotFoundError,
    BiometricNotSupportedOrPermissionDeniedError,
    BiometricNoEnrollmentError,
    BiometricNoPasscodeError,
    BiometricLockoutError,
} from '@authgear/react-native'
​
if (e instanceof CancelError) {
    // user cancel
} else if (e instanceof BiometricPrivateKeyNotFoundError) {
    // biometric info has changed. e.g. Touch ID or Face ID has changed.
    // user have to set up biometric authentication again
} else if (e instanceof BiometricNoEnrollmentError) {
    // device does not have biometric set up
    // e.g. have not set up Face ID or Touch ID in the device
} else if (e instanceof BiometricNotSupportedOrPermissionDeniedError) {
    // biometric is not supported in the current device
    // or user has denied the permission of using Face ID
} else if (e instanceof BiometricNoPasscodeError) {
    // device does not have unlock credential or passcode set up
} else if (e instanceof BiometricLockoutError) {
    // the biometric is locked out due to too many failed attempts
} else {
    // other error
    // you may consider showing a generic error message to the user
}
try {
    // ...
} on CancelException catch (e) {
    // user cancel
} on BiometricPrivateKeyNotFoundException catch (e) {
    // biometric info has changed. e.g. Touch ID or Face ID has changed.
    // user have to set up biometric authentication again
} on BiometricNoEnrollmentException catch (e) {
    // device does not have biometric set up
    // e.g. have not set up Face ID or Touch ID in the device
} on BiometricNotSupportedOrPermissionDeniedException catch (e) {
    // biometric is not supported in the current device
    // or user has denied the permission of using Face ID
} on BiometricNoPasscodeException catch (e) {
    // device does not have unlock credential or passcode set up
} on BiometricLockoutException catch (e) {
    // the biometric is locked out due to too many failed attempts
} catch (e) {
    // other error
    // you may consider showing a generic error message to the user
}
try 
{
    // ...
}
catch (OperationCanceledException ex)
{
    // user cancel
}
catch (BiometricPrivateKeyNotFoundException ex)
{
    // biometric info has changed. e.g. Touch ID or Face ID has changed.
    // user have to set up biometric authentication again
}
catch (BiometricNoEnrollmentException ex)
{
    // device does not have biometric set up
    // e.g. have not set up Face ID or Touch ID in the device
}
catch (BiometricNotSupportedOrPermissionDeniedException ex)
{
    // biometric is not supported in the current device
    // or user has denied the permission of using Face ID
}
catch (BiometricNoPasscodeException ex)
{
    // device does not have unlock credential or passcode set up
}
catch (BiometricLockoutException ex)
{
    // the biometric is locked out due to too many failed attempts
}
catch
{
    // other error
    // you may consider showing a generic error message to the user
}
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On this page
Overview
Enable biometric login in your application
Enable biometric login in mobile SDK
Biometric options
Code examples