PHP: Codeigniter: Password Hash

password_hashing.php

function new_registration($username, $email, $password, $confirmation_code)

{

    // Store the new user's information in the database.
 
    $key = $this->config->item('encryption_key');
    $salt1 = hash('sha512', $key . $password);
    $salt2 = hash('sha512', $password . $key);
    $hashed_password = hash('sha512', $salt1 . $password . $salt2);
 
    $userinfo = array(

        'username' => $username,
        'email' => $email,
        'password' => $hashed_password,
        'confirmation_code' => $confirmation_code
       
    );

    $this->db->insert('user', $userinfo);

}  


function check_login_exists($username, $password)

{
 
    $key = $this->config->item('encryption_key');
    $salt1 = hash('sha512', $key . $password);
    $salt2 = hash('sha512', $password . $key);
    $hashed_password = hash('sha512', $salt1 . $password . $salt2);
 
    $query_active = $this
        ->db->where('username', $username)
        ->where('password', $hashed_password)
        ->limit(1)
        ->get('user');
  
    if ($query_active->num_rows > 0)
 
    {
 
        return TRUE;
 
    }
 
    else
 
    {
 
        return FALSE;
 
    }

}