C# HttpClient with X509Certificate2 - WebException: The request was aborted: Could not create SSL/TLS secure channel

Question

I\'m working on implementing a payment service called Swish and testing it using this guide (Guide is in English even though filename is Swedish).

https://www.getswi

Answer 1

You can attach eventHandler to ServicePointManager like this:

ServicePointManager.ServerCertificateValidationCallback = ForcedAuthDelegate;

and implementation of ForcedAuthDelegate should return true to accept connection:

        static bool ForcedAuthDelegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            return true;
        }

Answer 2

Found an SSL test performed on the server:

https://www.ssllabs.com/ssltest/analyze.html?d=mss.swicpc.bankgirot.se

From here I could see that the following protocols were allowed:

After I set this everything worked:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;