在.net获得ssl证书

Question

我希望从任何给定的域名SSL证书获取数据.例如,我想放入任何网站地址,例如" http://stackoverflow.com ",我的代码将首先检查是否存在SSL证书.如果确实如此,我希望它能够取出证书的失效日期.[我正在阅读DB的Domainnames]示例:http://www.digicert.com/help/

我需要创建一个Web服务来检查到期日期.我怎么能实现它？ - 我查了很多不同的东西,比如RequestCertificateValidationCallback和ClientCertificates等.

我可能完全错了(因此我需要帮助)但是我会创建一个HTTPWebRequest然后以某种方式请求客户端证书和特定元素吗？

我尝试了提供@ SSL证书预取.NET的示例,但我得到了forbitten 403错误.

Answer 1

为此,您的项目需要参考System.Security:

using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;

//Do webrequest to get info on secure site
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://mail.google.com");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
response.Close();

//retrieve the ssl cert and assign it to an X509Certificate object
X509Certificate cert = request.ServicePoint.Certificate;

//convert the X509Certificate to an X509Certificate2 object by passing it into the constructor
X509Certificate2 cert2 = new X509Certificate2(cert);

string cn = cert2.GetIssuerName();
string cedate = cert2.GetExpirationDateString();
string cpub = cert2.GetPublicKeyString();

//display the cert dialog box
X509Certificate2UI.DisplayCertificate(cert2);

Answer 2

@cdev 的解决方案在 .NET Core 2.1 上对我不起作用。这似乎HttpWebRequest是不完全支持.NET的核心。

这是我在 .NET Core 上用来获取任何服务器的 X509 证书的函数：

// using System;
// using System.Net.Http;
// using System.Security.Cryptography.X509Certificates;
// using System.Threading.Tasks;

static async Task<X509Certificate2> GetServerCertificateAsync(string url)
{
    X509Certificate2 certificate = null;
    var httpClientHandler = new HttpClientHandler
    {
        ServerCertificateCustomValidationCallback = (_, cert, __, ___) =>
        {
            certificate = new X509Certificate2(cert.GetRawCertData());
            return true;
        }
    };

    var httpClient = new HttpClient(httpClientHandler);
    await httpClient.SendAsync(new HttpRequestMessage(HttpMethod.Head, url));

    return certificate ?? throw new NullReferenceException();
}

Answer 3

需要注意的一件事是您可能需要设置request.AllowAutoRedirect = False. 否则，如果服务器将 HTTPS 重定向到 HTTP，您将无法从HttpWebRequest对象获取证书。