// 加密

function encryptStr($str, $key){

  $block = mcrypt_get_block_size('des', 'ecb');

  $pad = $block - (strlen($str) % $block);

  $str .= str_repeat(chr($pad), $pad);

  $enc_str = mcrypt_encrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);

  return base64_encode($enc_str);

}

// 解密

function decryptStr($str, $key){

  $str = base64_decode($str);

  $str = mcrypt_decrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);

  $block = mcrypt_get_block_size('des', 'ecb');

  $pad = ord($str[($len = strlen($str)) - 1]);

  return substr($str, 0, strlen($str) - $pad);

}