How to Choose the Password Encoder Algorithm Dynamically

3.3 version

How to Choose the Password Encoder Algorithm Dynamically

Usually, the same password encoder is used for all users by configuring it to apply to all instances of a specific class:

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    # app/config/security.yml
    security:
        # ...
        encoders:
            Symfony\Component\Security\Core\User\User: sha512
    
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    <!-- app/config/security.xml -->
    <?xml version="1.0" encoding="UTF-8"?>
    <srv:container xmlns="http://symfony.com/schema/dic/security"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:srv="http://symfony.com/schema/dic/services"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd"
    >
        <config>
            <!-- ... -->
            <encoder class="Symfony\Component\Security\Core\User\User"
                algorithm="sha512"
            />
        </config>
    </srv:container>
    
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    // app/config/security.php
    use Symfony\Component\Security\Core\User\User;
    
    $container->loadFromExtension('security', array(
        // ...
        'encoders' => array(
            User::class => array(
                'algorithm' => 'sha512',
            ),
        ),
    ));
    

Another option is to use a "named" encoder and then select which encoder you want to use dynamically.

In the previous example, you've set the sha512 algorithm for Acme\UserBundle\Entity\User. This may be secure enough for a regular user, but what if you want your admins to have a stronger algorithm, for example bcrypt. This can be done with named encoders:

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    # app/config/security.yml
    security:
        # ...
        encoders:
            harsh:
                algorithm: bcrypt
                cost: 15
    
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    <!-- app/config/security.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <srv:container xmlns="http://symfony.com/schema/dic/security"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:srv="http://symfony.com/schema/dic/services"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd"
    >
    
        <config>
            <!-- ... -->
            <encoder class="harsh"
                algorithm="bcrypt"
                cost="15" />
        </config>
    </srv:container>
    
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    // app/config/security.php
    $container->loadFromExtension('security', array(
        // ...
        'encoders' => array(
            'harsh' => array(
                'algorithm' => 'bcrypt',
                'cost'      => '15'
            ),
        ),
    ));
    

This creates an encoder named harsh. In order for a User instance to use it, the class must implement EncoderAwareInterface. The interface requires one method - getEncoderName() - which should return the name of the encoder to use:

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// src/Acme/UserBundle/Entity/User.php
namespace Acme\UserBundle\Entity;

use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Security\Core\Encoder\EncoderAwareInterface;

class User implements UserInterface, EncoderAwareInterface
{
    public function getEncoderName()
    {
        if ($this->isAdmin()) {
            return 'harsh';
        }

        return null; // use the default encoder
    }
}

If you created your own password encoder implementing the PasswordEncoderInterface, you must register a service for it in order to use it as a named encoder:

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    # app/config/security.yml
    security:
        # ...
        encoders:
            app_encoder:
                id: 'app.password_encoder_service'
    
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    <!-- app/config/security.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <srv:container xmlns="http://symfony.com/schema/dic/security"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:srv="http://symfony.com/schema/dic/services"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd"
    >
    
        <config>
            <!-- ... -->
            <encoder class="app_encoder"
                id="app.password_encoder_service" />
        </config>
    </srv:container>
    
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    // app/config/security.php
    $container->loadFromExtension('security', array(
        // ...
        'encoders' => array(
            'app_encoder' => array(
                'id' => 'app.password_encoder_service'
            ),
        ),
    ));
    

This creates an encoder named app_encoder from a service named app.password_encoder_service.

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