1.在http辅助类中添加方法如下：

        private static bool RemoteCertificateValidate(object sender, X509Certificate cert,X509Chain chain, SslPolicyErrors error)
        {
            // trust any certificate!!!
            System.Console.WriteLine("Warning, trust any certificate");
            //为了通过证书验证，总是返回true
            return true;
        }

2.在http辅助类的构造方法添加如下代码：

ServicePointManager.ServerCertificateValidationCallback += RemoteCertificateValidate;//验证服务器证书回调自动验证

参考：http://wangzhiyu811.blog.163.com/blog/static/127254044201222462536173/