Question

我使用以下代码并获得HttpRequestException例外：

using (var handler = new HttpClientHandler())
{
    handler.ClientCertificateOptions = ClientCertificateOption.Manual;
    handler.SslProtocols = SslProtocols.Tls12;
    handler.ClientCertificates.Add(new X509Certificate2(@"C:\certificates\cert.pfx"));

    // I also tried to add another certificates that was provided to https access 
    // by administrators of the site, but it still doesn't work.
    //handler.ClientCertificates.Add(new X509Certificate2(@"C:\certificates\cert.crt"));
    //handler.ClientCertificates.Add(new X509Certificate2(@"C:\certificates\cert_ca.crt"));

    using (var client = new HttpClient(handler))
    {
        var response = client.GetAsync("https://someurl.com/api.php?arg1=some&arg2=test").GetAwaiter().GetResult();
        // ^ HttpRequestException: An error occurred while sending the request.
    }
}

例外：

WinHttpException: A security error occurred
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult()
    System.Net.Http.WinHttpHandler+<StartRequest>d__105.MoveNext()

HttpRequestException: An error occurred while sending the request.
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult()
    System.Net.Http.HttpClient+<FinishSendAsync>d__58.MoveNext()
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    System.Runtime.CompilerServices.TaskAwaiter.GetResult()
    MyApp.Web.Controllers.HomeController.Test() in HomeController.cs
        var response = client.GetAsync("https://someurl.com/api.php?arg1=some&arg2=test").GetAwaiter().GetResult();
    lambda_method(Closure , object , Object[] )
    Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeActionMethodAsync>d__27.MoveNext()

我还尝试将相同的证书导出到Windows证书存储区并通过谷歌浏览器使用它并且工作正常（浏览器要求我确认已安装的证书，然后加载资源）。

为什么它不能在我的代码中工作？

已更新

我还尝试添加回调来验证证书：

handler.ServerCertificateCustomValidationCallback = (message, certificate2, arg3, arg4) =>
{
    // I set a breakpoint to this point but it is not catched.
    return true;
};

UPDATED2

证书使用SHA-1。在support for SHA1 certs is being withdrawn的评论中提到了Neil Moss。如果这是它无法正常工作的真正原因，是否有解决方法？

解

谢谢Neil Moss的解决方案。他建议使用Tls标志进行SSL协议。

handler.SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls11 | SslProtocols.Tls;

但它还需要以下内容：

handler.ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => true;

我加上这个之后就可以了。

Answer 1

根据this SO post，您必须使用ServicePointManager启用TLS1.2。

System.Net.ServicePointManager.SecurityProtocol =
    SecurityProtocolType.Tls12 | 
    SecurityProtocolType.Tls11 | 
    SecurityProtocolType.Tls; // comparable to modern browsers

另外值得注意的是，ServicePointManager.SecurityProtocols属性的MSDN documentation生成了这个语句：

.NET Framework 4.6包含一个阻止的新安全功能用于连接的不安全密码和散列算法。

这表明某种形式的SHA1阻止可能到位。

Answer 2

这是一个非常有用的文档。对于ASP.NET Core 2.0，答案应用如下（结果成功）：

using (var handler = new HttpClientHandler())
{
    handler.ServerCertificateCustomValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true;
    handler.SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls11 | SslProtocols.Tls;
    using (HttpClient client = new HttpClient(handler))
    {
        string requestObjJson = requestObj.ToJson();
        var address = new Uri($"https://yourcompany.com/");
        string token = GetToken();
        client.BaseAddress = address;
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
        var contentData = new StringContent(requestObjJson, System.Text.Encoding.UTF8, "application/json");
        using (var response = await client.PostAsync("yourcompany/new-employee", contentData))
        {
            var content = response.Content.ReadAsStringAsync();
            var taskResult = content.Result;
            JObject resultObj = JObject.Parse(taskResult);
            return resultObj;
        }
    }
}

Answer 3

根据documentation，最好使用无。无“允许操作系统选择要使用的最佳协议，并阻止不安全的协议。除非您的应用有特定理由不这样做，否则您应该使用此字段”

使用HttpClient，HTTPS请求失败

3 个答案: