Make Https call using HttpClient

Question

I have been using HttpClient for making WebApi calls using C   Seems neat  amp  fast way compared to WebClient  However I am stuck up while making Https calls   How can I make below code to make Https calls   HttpClient httpClient   new HttpClient    httpClient BaseAddress   new Uri  https   foobar com     httpClient DefaultRequestHeaders Accept Clear    httpClient DefaultRequestHeaders Accept Add                  new MediaTypeWithQualityHeaderValue  application xml      var task   httpClient PostAsXmlAsync lt DeviceRequest gt                    api SaveData   request     EDIT 1  The code above works fine for making http calls  But when I change the scheme to https it does not work  Here is the error obtained      The underlying connection was closed  Could not establish trust   relationship for the SSL TLS secure channel    EDIT 2  Changing the scheme to https is  step one       How do I supply certificate  amp  public   private key along with C    request

User · Answer

There is a non-global setting at the level of HttpClientHandler:

var handler = new HttpClientHandler()
{
    SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls11 | SslProtocols.Tls
};

var client = new HttpClient(handler);

Thus one enables latest TLS versions.

Note, that the default value SslProtocols.Default is actually SslProtocols.Ssl3 | SslProtocols.Tls (checked for .Net Core 2.1 and .Net Framework 4.7.1).

User · Answer

I was also getting the error      The underlying connection was closed  Could not establish trust   relationship for the SSL TLS secure channel        with a Xamarin Forms Android-targeting application attempting to request resources from an API provider that required TLS 1 3    The solution was to update the project configuration to swap out the Xamarin  managed    NET  http client  that doesn t support TLS 1 3 as of Xamarin Forms v2 5   and instead use the android native client    It s a simple project toggle in visual studio  See screenshot below    Project Properties Android Options Advanced List item Change  HttpClient implementation  to  Android  Change SSL TLS implementation to  Native TLS 1 2

User · Answer

Simply specify HTTPS in the URI   new Uri  https   foobar com       Foobar com will need to have a trusted SSL cert or your calls will fail with untrusted error   EDIT Answer  ClientCertificates with HttpClient  WebRequestHandler handler   new WebRequestHandler    X509Certificate2 certificate   GetMyX509Certificate    handler ClientCertificates Add certificate   HttpClient client   new HttpClient handler     EDIT Answer2  If the server you are connecting to has disabled SSL  TLS 1 0  and 1 1 and you are still running  NET framework 4 5 or below  you need to make a choice   Upgrade to  Net 4 6   Supports TLS 1 2 by default  Add registry changes to instruct 4 5 to connect over TLS1 2   See  salesforce writeup for compat and keys to change OR checkout IISCrypto see Ronald Ramos answer comments  Add application code to manually configure  NET to connect over TLS1 2  see Ronald Ramos answer

User · Answer

If the server only supports higher TLS version like TLS 1 2 only  it will still fail unless your client PC is configured to use higher TLS version by default  To overcome this problem add the following in your code   System Net ServicePointManager SecurityProtocol   SecurityProtocolType Tls12   SecurityProtocolType Tls11   SecurityProtocolType Tls    Modifying your example code  it would be  HttpClient httpClient   new HttpClient          specify to use TLS 1 2 as default connection System Net ServicePointManager SecurityProtocol   SecurityProtocolType Tls12   SecurityProtocolType Tls11   SecurityProtocolType Tls   httpClient BaseAddress   new Uri  https   foobar com     httpClient DefaultRequestHeaders Accept Clear    httpClient DefaultRequestHeaders Accept Add new MediaTypeWithQualityHeaderValue  application xml      var task   httpClient PostAsXmlAsync lt DeviceRequest gt   api SaveData   request

User · Answer

I had the same problem when connecting to GitHub  which requires a user agent  Thus it is sufficient to provide this rather than generating a certificate  var client   new HttpClient     client BaseAddress   new Uri  https   api github com    client DefaultRequestHeaders Add       Authorization        token 123456789307d8c1d138ddb0848ede028ed30567    client DefaultRequestHeaders Accept Add      new MediaTypeWithQualityHeaderValue  application json     client DefaultRequestHeaders Add       User-Agent        Mozilla 5 0  Windows NT 6 1  AppleWebKit 537 36  KHTML  like Gecko  Chrome 41 0 2228 0 Safari 537 36

User · Answer

Just specifying HTTPS in the URI should do the trick   httpClient BaseAddress   new Uri  https   foobar com       If the request works with HTTP but fails with HTTPS then this is most certainly a certificate issue  Make sure the caller trusts the certificate issuer and that the certificate is not expired  A quick and easy way to check that is to try making the query in a browser   You also may want to check on the server  if it s yours and   or if you can  that it is set to serve HTTPS requests properly

User · Answer

I had this issue and in my case the solution was stupidly simple  open Visual Studio with Administrator rights  I tried all the above solutions and it didn t work until I did this  Hope it saves someone some precious time

User · Answer

When connect to https I got this error too  I add this line before HttpClient httpClient   new HttpClient    and connect successfully   ServicePointManager ServerCertificateValidationCallback   delegate   return true       I know it from This Answer and Another Similar Anwser and the comment mentions      This is a hack useful in development so putting a  if DEBUG  endif statement around it is the least you should do to make this safer and stop this ending up in production   Besides  I didn t try the method in Another Answer that use new X509Certificate   or new X509Certificate2   to make a Certificate  I m  not sure simply create by new   will work or not   EDIT   Some References   Create a Self-Signed Server Certificate in IIS 7  Import and Export SSL Certificates in IIS 7  Convert  pfx to  cer  Best practices for using ServerCertificateValidationCallback  I find value of Thumbprint is equal to x509certificate GetCertHashString     Retrieve the Thumbprint of a Certificate

User · Answer

I agree with felickz but also i want to add an example for clarifying the usage in c   I use SSL in windows service as follows        var certificatePath   System IO Path Combine System AppDomain CurrentDomain BaseDirectory   bin        gateway   new GatewayService        gateway PreAuthenticate   true        X509Certificate2 cert   new X509Certificate2 certificatePath      Attached my certificate pfx   certificate password        gateway ClientCertificates Add cert        ServicePointManager SecurityProtocol   SecurityProtocolType Tls12      gateway UserAgent   Guid NewGuid   ToString        gateway Timeout   int MaxValue    If I m going to use it in a web application  I m just changing the implementation on the proxy side like this   public partial class GatewayService   System Web Services Protocols SoapHttpClientProtocol    to   gt  Microsoft Web Services2 WebServicesClientProtocol

User · Answer

Your code should be modified in this way   httpClient BaseAddress   new Uri  https   foobar com       You have just to use the https  URI scheme  There s a useful page here on MSDN about the secure HTTP connections  Indeed      Use the https  URI scheme      The HTTP Protocol defines two URI schemes       http   Used for unencrypted connections       https   Used for secure connections that should be encrypted  This option also uses digital certificates and certificate authorities to verify that the server is who it claims to be    Moreover  consider that the HTTPS connections use a SSL certificate  Make sure your secure connection has this certificate otherwise the requests will fail   EDIT      Above code works fine for making http calls  But when I change the   scheme to https it does not work  let me post the error    What does it mean doesn t work  The requests fail  An exception is thrown  Clarify your question   If the requests fail  then the issue should be the SSL certificate   To fix the issue  you can use the class HttpWebRequest and then its property ClientCertificate  Furthermore  you can find here a useful sample about how to make a HTTPS request using the certificate   An example is the following  as shown in the MSDN page linked before      You must change the path to point to your  cer file location   X509Certificate Cert   X509Certificate CreateFromCertFile  C   mycert cer       Handle any certificate errors on the certificate from the server  ServicePointManager CertificatePolicy   new CertPolicy       You must change the URL to point to your Web server  HttpWebRequest Request    HttpWebRequest WebRequest Create  https   YourServer sample asp    Request ClientCertificates Add Cert   Request UserAgent    Client Cert Sample   Request Method    GET   HttpWebResponse Response    HttpWebResponse Request GetResponse

User · Answer

Add the below declarations to your class   public const SslProtocols  Tls12    SslProtocols 0x00000C00  public const SecurityProtocolType Tls12    SecurityProtocolType  Tls12    After   var client   new HttpClient      And   ServicePointManager SecurityProtocol   Tls12  System Net ServicePointManager SecurityProtocol   SecurityProtocolType Ssl3     SecurityProtocolType Tls     Tls12    Happy

User · Answer

For error       The underlying connection was closed  Could not establish trust   relationship for the SSL TLS secure channel    I think that you need to accept certificate unconditionally with following code  ServicePointManager ServerCertificateValidationCallback          sender  cert  chain  sslPolicyErrors    gt  true    as Oppositional wrote in his answer to question  NET client connecting to ssl Web API

User · Answer

You can try using the ModernHttpClient Nuget Package  After downloading the package  you can implement it like this     var handler   new ModernHttpClient NativeMessageHandler           UseProxy   true         handler ClientCertificateOptions   ClientCertificateOption Automatic   handler PreAuthenticate   true   HttpClient client   new HttpClient handler

[c#] Make Https call using HttpClient

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