SSL，HttpWebRequest抛出PayPal WebException

Question

我正在尝试获取如下所示的PayPal访问令牌：https://developer.paypal.com/docs/integration/direct/make-your-first-call/#get-an-access-token

我的C#代码如下所示：

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://api.sandbox.paypal.com/v1/oauth2/token");
request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(clientId + ":" + clientSecret));
request.Accept = "application/json";
request.Headers.Add("Accept-Language", "en_US");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = 10000;

byte[] postBytes = Encoding.ASCII.GetBytes("grant_type=client_credentials");
request.ContentLength = postBytes.Length;

ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

Stream postStream = request.GetRequestStream(); // ###### Here I get the Exception! ######
postStream.Write(postBytes, 0, postBytes.Length);
postStream.Flush();
postStream.Close();

HttpWebResponse response = (HttpWebResponse)request.GetResponse();

当调用request.GetRequestStream()时，我得到一个德语文本为"Die Anfrage wurde abgebrochen: Es konnte kein geschützter SSL/TLS-Kanal erstellt werden“的WebException。这意味着它无法创建安全的SSL/TLS通道。

我做错了什么？有人能帮我吗？

谢谢，沃克

Answer 1

我找到了解决方案：

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; //SecurityProtocolType.Tls12;

也许这对其他人也有帮助。

Answer 2

正确的，他们不再使用SSL3，这就是错误的来源。

您可以使用TLS 1.1和1.2

ServicePointManager.SecurityProtocol =  SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;