$aesKey = base64_decode($session_key);
//这里需特别注意 PHP获取参数会把 “+“ 转成空格
$encryptedData = str_replace(' ', '+', $encryptedData);
$aesCipher = base64_decode($encryptedData);
$aesIV = base64_decode($iv);
$result = openssl_decrypt( $aesCipher, "AES-128-CBC", $aesKey, 1, $aesIV);