Must-use plugin for WordPress to swap phpass to PHP 5.5's new password_hash and password_verify using bcrypt

password_bcrypt.php

<?php
/**
 * Plugin Name: WP PASSWORD_BCRYPT 
 * Plugin URI:  http://bitpiston.com/
 * Description: Replaces wp_hash_password and wp_check_password's phpass hasher with PHP 5.5's password_hash and password_verify using bcrypt.
 * Author:      BitPiston Studios
 * Author URI:  http://bitpiston.com/
 * Version:     1.2
 * Licence:     BSD
 */

function wp_hash_password($password)
{
    $hash = password_hash($password, PASSWORD_DEFAULT);

    return $hash;
}

function wp_check_password($password, $hash, $user_id = '')
{
    // Check for older passwords and update them
    if ( substr($hash, 0, 3) == '$P$' )
    {
        global $wp_hasher;
        
        if ( empty($wp_hasher) ) 
        {
            require_once(ABSPATH . WPINC . '/class-phpass.php');
            
            $wp_hasher = new PasswordHash(8, true);
        }
        
        $check = $wp_hasher->CheckPassword($password, $hash);
        
        if ( $check && $user_id )
        {
            // Rehash using new hash if they match.
            wp_set_password($password, $user_id);
            
            $hash = wp_hash_password($password);
        }
    }
    
    $check = password_verify($password, $hash);

    return apply_filters('check_password', $check, $password, $hash, $user_id);
}

Superseded by https://github.com/roots/wp-password-bcrypt