Implementing a custom two-factor provider

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Implementing a custom two-factor provider

Getting started

A good starting point are the Google Authenticator, TOTP and email authentication implementations, which are available in the codebase. Have a look at the follow files:

You will get the basic idea how to implement a custom two-factor method.

The TwoFactorProviderInterface

You have to create a service, which implements the Scheb\TwoFactorBundle\Security\TwoFactor\Provider\TwoFactorProviderInterface interface. It requires these methods:

beginAuthentication

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        public function beginAuthentication(AuthenticationContextInterface $context): bool;
    

The method is called after successful login. It receives an AuthenticationContextInterface object as the argument (see class Scheb\TwoFactorBundle\Security\TwoFactor\AuthenticationContext) which contains the request object the authentication token, the user entity and other information.

The method has to decide if the user should be asked for two-factor authentication from that provider. In that case return true, otherwise false.

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        public function prepareAuthentication($user): void;
    

This method is where you should do the preparation work for your two-factor provider. E.g. the email provider is generating a code and sending it to the user.

validateAuthenticationCode

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        public function validateAuthenticationCode($user, string $authenticationCode): bool;
    

This method is responsible for validating the authentication code entered by the user. Return true if the code was correct or false when it was wrong.

getFormRenderer

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        public function getFormRenderer(): TwoFactorFormRendererInterface;
    

This method has to provide a service for rendering the authentication form. Such a service has to implement the Scheb\TwoFactorBundle\Security\TwoFactor\Provider\TwoFactorFormRendererInterface interface:

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        public function renderForm(Request $request, array $templateVars): Response;
    

How you render the form is totally up to you. The only important thing is to return a Response, which could also be a RedirectResponse redirect to an external service. A default implementation for rendering forms with Twig is available as Scheb\TwoFactorBundle\Security\TwoFactor\Provider\DefaultTwoFactorFormRenderer.

Register the provider

Now you have to register your two-factor provider class as a service.

A tag named scheb_two_factor.provider will make your provider available to the bundle. The tag attribute alias has to be set and must be an application-wide unique identifier for the authentication provider.

Note

The aliases google, totp and email are reserved by the authentication methods that are included in the bundle.

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        # config/services.yaml
services:
    # ...
    acme.custom_two_factor_provider:
        class: Acme\Demo\MyTwoFactorProvider
        tags:
            - { name: scheb_two_factor.provider, alias: acme_two_factor_provider }
    

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.

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