[C#] HttpWebRequest 루트 인증서와 해당 도메인 인증서 확인하기

static void Main(string[] args) {
	try {
		ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(ValidateServerCertificate);
		HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://원하는_도메인_주소");
		request.Method = "GET";
		HttpWebResponse response = (HttpWebResponse)request.GetResponse();
		Stream stream = response.GetResponseStream();
		StreamReader reader = new StreamReader(stream, Encoding.UTF8);
		string text = reader.ReadToEnd();
		stream.Close();
		response.Close();
		reader.Close();
	} catch (Exception ex) {
		Console.WriteLine(ex.Message);
	}
}

static bool ValidateServerCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) {
	try {
		if (sslPolicyErrors != SslPolicyErrors.None) {//SSL이 오류인 경우
			Console.WriteLine(sslPolicyErrors);
			return false;
		}

		Console.WriteLine("Subject : " + certificate.Subject);
		Console.WriteLine("Issuer : " + certificate.Issuer);
		Console.WriteLine("Hash : " + certificate.GetCertHashString());

		X509ChainElementCollection x509ChainElement = chain.ChainElements;
		X509Certificate rootCA = x509ChainElement[x509ChainElement.Count - 1].Certificate;
        
		Console.WriteLine("Root CA Subject : " + rootCA.Subject);
		Console.WriteLine("Root CA Issuer : " + rootCA.Issuer);
		Console.WriteLine("Root CA Hash : " + rootCA.GetCertHashString());

		return true;
	} catch (Exception) {
		return false;
	}
}