All that you need to do is:
public void ConfigureSSL()
{
ServicePointManager.ServerCertificateValidationCallback = CertChecker;
}
private bool CertChecker(object sender, X509Certificate certificate,
X509Chain chain, SslPolicyErrors errors)
{
return certificate.Subject == "Certificate SSL Subject for your site";
}
Call
ConfigureSSL()
method before the first request.