[筆記]webRequest API與SSL、TLS 相關問題

參考文件：

• Bypass SSL certificate validation

問題：

1. 使用HttpWebRequest webRequest方法，遠端傳回
   Could not establish trust relationship for the SSL/TLS secure channel
   
   原因是因為網頁會詢問你是否繼續。
   所以再詢問前加上
   ServicePointManager.ServerCertificateValidationCallback = delegate { return true; }; 
2. 另外，有可能因為TLS版本不同導致呼叫失敗。可以加上ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;

範例：

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;
ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
HttpWebRequest webRequest=(HttpWebRequest)WebRequest.Create("https://api.com");