SSL certificate validation .NET vs Mono

Question

I have problem with validating SSL certificate in my Unity game.

I have made simple test code which is:

ServicePointManager.ServerCertificateValidationCallback += ServerCertificateValidationCallback;


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


public void Test()
{
    WebClient w = new WebClient();
    string downloadString = w.DownloadString("https://encrypted.google.com/");
}

I have implemented this in .NET 4.5 and in Unity (Mono) and the problem is that this certificate is validated properly on .NET, but in Mono I'm getting:

SslPolicyErrors: RemoteCertificateChainErrors
ChainStatus:
    PartialChain
    RevocationStatusUnknown
    OfflineRevocation

Why this happens? Should I set something in Mono additionally to handle that?

Thanks

Answer 1

The problem is mono doesn't carry any Root CA or CRL, see Why doesn’t Mono includes root certificates. And if you try to develop mobile game, there was a cert load bug, which return incomplete X509Chain and was fixed in Mono 3.6.0.

According to official advices, update unity to Unity2017 will built-in mono 4.5 which solved this annoyed problem. Otherwise you may have to install CA certs manually.