WeChat Pay HTTPS server certificate verification (php)

WeChat Pay replaces the CA certificate, indicating that it may affect the payment. 
/**Request method post
*Request format xml
*Test WeChat payment certificate
* @param mch_id WeChat merchant number
* @param nonce_str random number
* @param sign signature
*/
public function index()
{
    $data=array(
        "mch_id"= >'Merchant ID',
        "nonce_str"=> md5(time()),
    );
    $newdata = http_build_query ($data)."&key=payment key";
    $sign = strtoupper(md5($newdata));
    $ data["sign"] = $sign;

    $postdata = arrayToXml($data);

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://apitest.mch.weixin.qq.com/sandboxnew/ pay/getsignkey");
    curl_setopt($ch, CURLOPT_POST, 1); 
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata); 

//add the following two lines when curl 60 is wrong 
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
     curl_setopt($ch, CURLOPT_HEADER,0); 
    $returncode =curl_exec($ch); 
    if($error=curl_errno($ch)){ 
        echo $error; 
    } 
    curl_close($ch); 

    $toXml = simplexml_load_string( $returncode, 'SimpleXMLElement', LIBXML_NOCDATA); 
    $arrXml = (array)$toXml; 
    if ($arrXml['return_code'] == 'SUCCESS') { 

        die('Your server is verified by WeChat Pay HTTPS server certificate') ; 
    } 
    if ($arrXml['return_code'] == 'FAIL') {
        die("Your server failed to authenticate: " . $arrXml['return_msg'] . ";" . "<a hre='https://pay.weixin.qq.com/wiki/doc/api/micropay. php?chapter=23_4'>Click me to see how to install the root CA certificate required by WeChat</a>"); 
    } 
}