function encrypt($str, $key)
{
    # Add PKCS7 padding.
    $block = mcrypt_get_block_size('des', 'ecb');
    if (($pad = $block - (strlen($str) % $block)) < $block) {
      $str .= str_repeat(chr($pad), $pad);
    }

    return mcrypt_encrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);
}

function decrypt($str, $key)
{
    $str = mcrypt_decrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);

    # Strip padding out.
    $block = mcrypt_get_block_size('des', 'ecb');
    $pad = ord($str[($len = strlen($str)) - 1]);
    if ($pad && $pad < $block && preg_match(
          '/' . chr($pad) . '{' . $pad . '}$/', $str
                                            )
       ) {
      return substr($str, 0, strlen($str) - $pad);
    }
    return $str;
}