MutualTLS authentication in C# for httpclient

[vamshimupparaju]

Hi Team,

Can you please help me in this from past few days I am trying to resolve the below scenario.

I have private key and certificate key using this I have to do the mutual authentication and send request to one of my end point.

below is the code I am trying to work on but some how I am getting 401 unauthorized issue.

        ****string keyPem = privateKeyString;
        byte[] keyDer = Convert.FromBase64String(keyPem);
        
        X509Certificate2 certWithKey;
        byte[] keycer = Encoding.ASCII.GetBytes(certString);
        X509Certificate2 certOnly = new X509Certificate2(keycer);
        System.Security.Cryptography.RSA rsa = RSA.Create();
     
        rsa.ImportPkcs8PrivateKey(keyDer, out _);
        certWithKey = certOnly.CopyWithPrivateKey(rsa);

        var certificate = new X509Certificate2(certWithKey.Export(X509ContentType.Pfx));

       HttpClientHandler httpClientHandler = new HttpClientHandler();
        httpClientHandler.ClientCertificateOptions = ClientCertificateOption.Manual;
        httpClientHandler.SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls11 | SslProtocols.Tls;


        httpClientHandler.ClientCertificates.Add(certificate);
        httpClientHandler.ClientCertificateOptions = ClientCertificateOption.Manual;

        HttpClient httpClient = new HttpClient(httpClientHandler);

        string _ContentType = "application/x-www-form-urlencoded";
        httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(_ContentType));
        HttpResponseMessage httpResponseMessage = await httpClient.PostAsync("endpointurl", null);****

Please help me in this whether I am doing anything wrong in the above

@karelz @henning-krause @bartonjs @davidsh @Drawaes @npnelson @stephentoub @jhudsoncedaron

Thanks & Regards,
Vamshi Krishna

[karelz]

Duplicate - see #68070 (comment)