How to Use A Different Password Encoder Algorithm Per User

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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    # config/packages/security.yaml
    security:
        # ...
        encoders:
            App\Entity\User:
                algorithm: auto
                cost: 12
    
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    <!-- config/packages/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
            https://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/security
            https://symfony.com/schema/dic/security/security-1.0.xsd"
    >
        <config>
            <!-- ... -->
            <encoder class="App\Entity\User"
                algorithm="auto"
                cost=12
            />
        </config>
    </srv:container>
    
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    // config/packages/security.php
    use App\Entity\User;
    
    $container->loadFromExtension('security', [
        // ...
        'encoders' => [
            User::class => [
                'algorithm' => 'auto',
                'cost' => 12,
            ],
        ],
    ]);
    

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 auto algorithm for App\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 auto with a higher cost. This can be done with named encoders:

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    # config/packages/security.yaml
    security:
        # ...
        encoders:
            harsh:
                algorithm: auto
                cost: 15
    
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    <!-- config/packages/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
            https://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/security
            https://symfony.com/schema/dic/security/security-1.0.xsd"
    >
    
        <config>
            <!-- ... -->
            <encoder class="harsh"
                algorithm="auto"
                cost="15"/>
        </config>
    </srv:container>
    
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    // config/packages/security.php
    $container->loadFromExtension('security', [
        // ...
        'encoders' => [
            'harsh' => [
                'algorithm' => 'auto',
                'cost'      => '15',
            ],
        ],
    ]);
    

Note

If you are running PHP 7.2+ or have the libsodium extension installed, then the recommended hashing algorithm to use is Sodium.

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:

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

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

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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    # config/packages/security.yaml
    security:
        # ...
        encoders:
            app_encoder:
                id: 'App\Security\Encoder\MyCustomPasswordEncoder'
    
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    <!-- config/packages/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
            https://symfony.com/schema/dic/services/services-1.0.xsd
            http://symfony.com/schema/dic/security
            https://symfony.com/schema/dic/security/security-1.0.xsd"
    >
    
        <config>
            <!-- ... -->
            <encoder class="app_encoder"
                id="App\Security\Encoder\MyCustomPasswordEncoder"/>
        </config>
    </srv:container>
    
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    // config/packages/security.php
    // ...
    use App\Security\Encoder\MyCustomPasswordEncoder;
    
    $container->loadFromExtension('security', [
        // ...
        'encoders' => [
            'app_encoder' => [
                'id' => MyCustomPasswordEncoder::class,
            ],
        ],
    ]);
    

This creates an encoder named app_encoder from a service with the ID App\Security\Encoder\MyCustomPasswordEncoder.