合单支付json:

{"combine_appid":"wxcexxx3c66725", // //这里小程序appid ? 还是要填写 电商收付通对应的服务号的appid?

"combine_out_trade_no":"CB1586678546","combine_mchid":"1579883051","scene_info":{"device_id":"POSM1:1","payer_client_ip":"14.17.22.32"},"sub_orders":[{"mchid":"1579883051","attach":"ORD20200412102827SN000021","amount":{"total_amount":200,"currency":"CNY"},"out_trade_no":"out_trade_no1586678546","sub_mchid":"1585305101","profit_sharing":true,"description":"秋店(T)ORD:ORD20200412102827SN000021买家wx_13917355566"}],"combine_payer_info":{"openid":"ofGBt5TrGgf0HjiS4rAPFrvFNI7c"},"notify_url":"https://shop.bnbvista.com/payment/wxpayecommerce/market/notify/1585305101.php"}

返回了 prepay_id: "up_wx121602275099748db8f8e66b1471339100"

然后使用php rsa签名

   public function getEncryptSHA256withRSA($str){ 

       //$str是待加密字符串 

         $public_key_path = $this->mch_private_key;

         $public_key = file_get_contents($public_key_path); 

         $encrypted = ''; 

         if (openssl_sign($str,$encrypted,$public_key,"sha256WithRSAEncryption")) { 

             //base64编码 

             $sign = base64_encode($encrypted);

         } else {

             throw new Exception('encrypt failed');

         }

         return $sign;

     }

            $message =  $appid."\n".

                      $timestamp."\n".

                        $nonce."\n".

                        $prepayid."\n";

//从小程序端发送服务端php生成签名值paysign,               

 appId: "wxcexxx3c66725" //传的是当前小程序的appid ，不是电商收付通的服务号appid

nonceStr: "RyTNJk6kRrJRyiRawjCZTZzwh6QPJCK7"

package: "prepay_id=up_wx121602275099748db8f8e66b1471339100"

  $sign= $this->getEncryptSHA256withRSA($message);

       return   $sign ;

生成返回paySign:

小程序端使用以下参数和paySign，发起支付时候，跳出支付窗口时候，提示支付验证签名失败。

1. appId: "wxcexxx3c66725" //传的是当前小程序的appid ，不是电商收付通的服务号appid
2. nonceStr: "RyTNJk6kRrJRyiRawjCZTZzwh6QPJCK7"
3. package: "prepay_id=up_wx121602275099748db8f8e66b1471339100"
4. paySign: "BQ/ir0qJNUfR1Ly4VDcBMwbCa6rngwbO2Ey60SrEuxTBo1gQknII8hjWTz/AQrsbqfERnonJHZ8HCWR2RqoG6xboYkgZ4s4knajtieZH5bQFcRWL8osU98I1WTDVOHcWRcDD/cM1Dx9JW2LujBlR5tC/PRj2pXsCjQFE33maLxacVf83sCFKkn6gnUH1Ihg30CsNC8hZFvyIjirYExkmAhzaaIwQXmTXqdVWqMVwq29r0Hql+2hQ8QFnMLbVw3+vsyACLmyH7NnrXp88Hbc+4Y80wWkV4BKsPZ4CfBJH4Azkec68ZK0qcuYJL3qP5eTruMw4bsDxJI2rzctgZntpug==
5. "
6. signType: "RSA"
7. timeStamp: "1586678546"

请问有大侠可指点下，这个流程上有什么问题吗？

RSA签名程序有问题还是参数上传递不对？