Multi Factor Authentication in PnP Flutter SDK

At Web3Auth, we prioritize your security by offering Multi-Factor Authentication (MFA). MFA is an extra layer of protection that verifies your identity when accessing your account. To ensure ownership, you must provide two or more different backup factors. You have the option to choose from the device, social, backup factor (seed phrase), and password factors to guarantee access to your Web3 account. Once you create a recovery factor, MFA is enabled, and your keys are divided into three shares for off-chain multi-sig, making the key self-custodial. With backup factors, you can easily recover your account if you lose access to your original device or helps login into a new device.

note

mfaSettings is a paid feature and the minimum pricing plan to use this SDK in a production environment is the SCALE Plan. You can use this feature in sapphire_devnet for free.

Enable using the MFA Level

For a dApp, we provide various options to set up Multi-Factor Authentication. You can customize the MFA screen by passing the mfaLevel parameter in login method. You can enable or disable a backup factor and change their order. Currently, there are four values for MFA level.

Note

If you are using default verifiers, your users may have set up MFA on other dApps that also use default Web3Auth verifiers. In this case, the MFA screen will continue to appear if the user has enabled MFA on other dApps. This is because MFA cannot be turned off once it is enabled.

MFA Level Options

MFA Level	Description
DEFAULT	Shows the MFA screen every third login.
OPTIONAL	Shows the MFA screen on every login, but user can skip it.
MANDATORY	Makes it mandatory to set up MFA after first login.
NONE	Skips the MFA setup screen

Usage

Web3AuthFlutter.login(
  LoginParams(
    loginProvider: Provider.google,
    mfaLevel: MFALevel.MANDATORY,
  ),
);

Explicitly enable MFA

The enableMFA method is used to trigger MFA setup flow for users. The method takes LoginParams which will used during custom verifiers. If you are using default login providers, you don't need to pass LoginParams. If you are using custom jwt verifiers, you need to pass the JWT token in loginParams as well.

Default Verifier

Usage

try {
  await Web3AuthFlutter.enableMFA();
} on UserCancelledException {
  log("User cancelled.");
} catch(e) {
  log("Unknown exception occurred");
}

Custom JWT Verifier

Usage

try {
    final loginParams = LoginParams(
        loginProvider: Provider.jwt,
        extraLoginOptions: ExtraLoginOptions(
            id_token: "YOUR_JWT_TOKEN",
        ),
    );

    await Web3AuthFlutter.enableMFA(loginParams);

} on UserCancelledException { log("User cancelled."); } catch(e) { log("Unknown exception
occurred"); }

Configure MFA Settings

You can configure the order of MFA, and enable or disable MFA type by passing the mfaSettings parameter in Web3AuthOptions during initialization.

Note

• At least two factors are mandatory when setting up the mfaSettings.
• If you set mandatory: true for all factors, the user must set up all four factors.
• If you set mandatory: false for all factors, the user can skip setting up MFA. But at least two factors are mandatory.
• If you set mandatory: true for some factors and mandatory: false for others, the user must set up the mandatory factors and can skip the optional factors. But, the user must set up at least two factors.
• The priority field is used to set the order of the factors. The factor with the lowest priority will be the first factor to be set up. The factor with the highest priority will be the last factor to be set up.

Parameters - MfaSettings

MfaSettings allows you to set the type of the MFA.

Table

Parameter	Description
deviceShareFactor?	MFA setting for deviceShareFactor. It accepts MfaSetting as a value.
backUpShareFactor?	MFA setting for backUpShareFactor. It accepts MfaSetting as a value.
socialBackupFactor?	MFA setting for socialBackupFactor. It accepts MfaSetting as a value.
passwordFactor?	MFA setting for passwordFactor. It accepts MfaSetting as a value.

Class

class MfaSettings {
  final MfaSetting? deviceShareFactor;
  final MfaSetting? backUpShareFactor;
  final MfaSetting? socialBackupFactor;
  final MfaSetting? passwordFactor;

  MfaSettings({
    this.deviceShareFactor,
    this.backUpShareFactor,
    this.socialBackupFactor,
    this.passwordFactor,
  });

  Map<String, dynamic> toJson() {
    return {
      'deviceShareFactor': deviceShareFactor,
      'backUpShareFactor': backUpShareFactor,
      'socialBackupFactor': socialBackupFactor,
      'passwordFactor': passwordFactor,
    };
  }
}

Parameters - MfaSetting

MfaSetting allows you to setup MFA setting for a particular MFA type.

Table

Parameter	Description
enable	Enable/Disable MFA. It accepts bool as a value.
priority?	Priority of MFA. It accepts int as a value, where valid range is from 1 to 4.
mandatory?	Mandatory/Optional MFA. It acccepts bool as a value.

Class

class MfaSetting {
  final bool enable;
  final int? priority;
  final bool? mandatory;

  MfaSetting({required this.enable, this.priority, this.mandatory});

  Map<String, dynamic> toJson() {
    return {'enable': enable, 'priority': priority, 'mandatory': mandatory};
  }
}

Usage

Future<void> initWeb3Auth() async {

  late final Uri redirectUrl;
  if (Platform.isAndroid) {
    redirectUrl = Uri.parse('{SCHEME}://{HOST}/auth');
    // w3a://com.example.w3aflutter/auth
  } else {
    redirectUrl = Uri.parse('{bundleId}://auth');
    // com.example.w3aflutter://auth
  }


  await Web3AuthFlutter.init(
    Web3AuthOptions(
    clientId: "WEB3AUTH_CLIENT_ID",
    network: Network.sapphire_mainnet,
    redirectUrl: redirectUrl,
    mfaSettings: MfaSettings(
      deviceShareFactor: MfaSetting(
        enable: true,
        priority: 4,
        mandatory: true,
      ),
      backUpShareFactor: MfaSetting(
        enable: true,
        priority: 2,
        mandatory: true,
      ),
      socialBackupFactor: MfaSetting(
        enable: true,
        priority: 3,
        mandatory: false,
      ),
      passwordFactor: MfaSetting(
        enable: true,
        priority: 1,
        mandatory: true,
      ),
    ),
  );

  await Web3AuthFlutter.initialize();
}