Using Single Factor Auth Flutter SDK

After successfully installing and initializing SingleFactorAuth, you can use it to authenticate your users and obtain their private and public keys.

Note

Web3Auth SFA Flutter SDK only works for users who have not enabled MFA. For MFA enabled users, you'll see an Error message.

Functionality Overview

The SingleFactorAuth instance natively provides the following methods:

Method	Description
connect	Use to login user and retrieve private key pair.
logout	Use to logout existing user.
connected	Use to check whether the user is logged in or not.
getSessionData	This method helps to get the session data for valid session.

Login User

tip

Please refer to the Authentication section for more details on the setting up your verifier and other authentication parameters.

To obtain a user's private key using the Web3Auth SFA Flutter SDK, you can call the connect method. The method accepts LoginParams, and returns SFAKey.

Parameters

Table

Parameter	Description
verifier	The verifier parameter takes the name of the custom verifier from the Web3Auth Dashboard. This is a required field that must be a String. If you're using an aggregate verifier, make sure to pass the aggregate verifier name.
verifierId	The verifierID takes the JWT verifier ID to be used for JWT/ID token verification. It can be an email, sub, or custom value available in the JWT token.
idToken	The idToken accepts a JWT token obtained from the user's login provider.
subVerifierInfoArray?	Sub verifier info. Usually used during the aggregate verifier. It takes List<TorusSubVerifierInfo> as a value.

Class

class LoginParams {
  final String verifier;
  final String verifierId;
  final String idToken;
  final String? aggregateVerifier;

  LoginParams({
    required this.verifier,
    required this.verifierId,
    required this.idToken,
    this.aggregateVerifier,
  });

  Map<String, dynamic> toJson() {
    return {
      'verifier': verifier,
      'verifierId': verifierId,
      'idToken': idToken,
      'aggregateVerifier': aggregateVerifier,
    };
  }
}

Usage

Single verifier

final loginParams = LoginParams(
  verifier: 'YOUR_VERIFIER_NAME',
  verifierId: 'YOUR_VERIFIER_ID',
  idToken: 'YOUR_ID_TOKEN',
);

try { final sessionData = await singleFactorAuthFlutter.connect(loginParams); } catch (e) { //
Handle error }

Aggregate verifier

final subVerifierInfoArray = [
  TorusSubVerifierInfo(
    'YOUR_SUB_VERIFIER_NAME',
    'YOUR_ID_TOKEN',
  ),
];

final loginParams = LoginParams(
  verifier: 'YOUR_AGGREGATE_VERIFIER_NAME',
  verifierId: 'YOUR_VERIFIER_ID',
  idToken: 'YOUR_ID_TOKEN',
  subVerifierInfoArray: subVerifierInfoArray,
);

try {
  final sessionData = await singleFactorAuthFlutter.connect(loginParams);
} catch (e) {
  // Handle error
}

Logout User

To logout the current user, you can use the logout method. Please note, the method will not logout the user from the authentication provider, it'll only logout and invalidate the Web3Auth session.

Usage

try {
  await singleFactorAuthFlutter.logout();
  // Logged out successfully
} catch (e) {
  // Handle error
}

Check User's Logged In Status

You can use the connected method to check whether the user is logged in Web3Auth or not. Please note, you should call this method after the initialize method if you want to check the user's connection status for an existing session.

Usage

final isConnected = await singleFactorAuthFlutter.connected();

Get Session Data

We have included Session Management in this SDK, so calling the getSessionData will retrive the user's SessionData without re-logging in the user if a user has an active session. Otherwise, it will return null.

tip

Please note, you should use this method after the initialize method.

Usage

final SessionData? sessionData = await singleFactorAuthFlutter.getSessionData();

if (sessionData != null) {
  // User is logged in
} else {
  // User is not logged in
}

Response

The SessionData has the following properties to retrive the relevant session information.

Name	Description
privateKey	Retrieves the user's private key.
publicAddress	Retrieves the user's public address.
userInfo?	Retrieves the user's information like email, name, verifier id, and more.
signatures?	Retrieves the node's signatures that are returned for request.