Custom MessageDigestPasswordEncoder class for Symfony2

MessageDigestPasswordEncoder.php

<?php

namespace Application\Bundle\MainBundle\Security\Encoder;

use Symfony\Component\Security\Core\Encoder\MessageDigestPasswordEncoder as BaseMessageDigestPasswordEncoder;

/**
 * Extends MessageDigestPasswordEncoder to support custom merging of password and salt strings.
 *
 * @author Jeremy Mikola <jmikola@gmail.com>
 */
class MessageDigestPasswordEncoder extends BaseMessageDigestPasswordEncoder
{
    /**
     * Demerges a merge password and salt string.
     *
     * @param string $mergedPasswordSalt The merged password and salt string
     * @throws \BadMethodCallException always
     */
    protected function demergePasswordAndSalt($mergedPasswordSalt)
    {
        throw new \BadMethodCallException('Password and salt cannot be demerged.');
    }

    /**
     * Merges a password and a salt.
     *
     * @param string $password
     * @param string $salt
     * @return string
     */
    protected function mergePasswordAndSalt($password, $salt)
    {
        return $salt . $password;
    }
}

security.xml

<?xml version="1.0" encoding="utf-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <parameters>
        <parameter key="security.encoder.digest.class">Application\Bundle\MainBundle\Security\Encoder\MessageDigestPasswordEncoder</parameter>
    </parameters>
</container>