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Connecting to a HTTPS server with SSL using Wininet, sending client certificate and reading response

, 2 Apr 2003
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A sample class which illustrates how to connect to a HTTPS server, the class sends the desired client certificate and authenticates the user.


I’ve recently needed to make a Secure Sockets Layer (SSL) connection to Visa server and send our signed client certificate in order to make our MPI application authorized. I searched many articles but could find just a few ones about the subject. I collected parts of the solution from different articles and MSDN, and implemented a simple class that performs this operation programmatically.

There’s InternetErrorDlg API for some purposes including sending client certificate modeling a selection dialog to the user. But in many cases, the programmer may require authentication without user interface (i.e. user interface requires an OK clicker J.. This might be useless for us if we want our program to do things automatically). This is done here by InternetSetOption() with INTERNET_OPTION_CLIENT_CERT_CONTEXT flag. Don’t forget that this option only works with Internet Explorer 5.01 or later (as MSDN writes).

INTERNET_OPTION_CLIENT_CERT_CONTEXT flag is not included in VC6.0 default headers. If you’ve platform SDK installed, that’s no problem, include the wininet header in sdk/include directory, else you may define it manually;


That should be ok if you don’t have old wininet.dll versions.

For readers who are not familiar with wininet, SSL or certificates:

I am not gonna tell what wininet functions do & how they are used nor about the certificates. These are generic subjects and much information can be gathered from so many resources such as MSDN. I will try to answer the questions if you send an email to me.

Well, the flow is simple. First we connect to the HTTPS server and send a HTTPS request. If the server asks for a signed client certificate, we open and dig through the system store(s) for the certificate context we need. Then resend our request but after attaching the certificate context. If the server is satisfied, we are authenticated.

  • ConnectToHttpsServer() summarizes the flow of the connection. This is the initial place.
  • SendHttpsRequest() sends a request. After that, if the server requires client certificate, we search it in the system store. If we find it, InternetSetOption() attaches the context to the connection. Then we try the SendHttpsRequest() again.

A sample usage of the class can be like this:

CSslConnection inetSec;
string sAgentName("My Firm"); 
string sServerName("");//Can be any https server address 
string sUserName("");//if required 
string sPass("");//if required 
string sObjectName("/xxx.asp");//there should be an object to send a verb 
string sOrganizationUnitName("3-D Secure Compliance TestFacility"); 
string strVerb = "POST";//I chose POST verb. That’s usually done 


         //The stores provided by the system 
         // are: MY, ROOT, SPC and CA 



inetSec.SetPort(9660);//443 is the default HTTPS port 


if (!inetSec.ConnectToHttpsServer(strVerb)) { 

    cout << inetSec.GetLastErrorString()  << " Code: " 
       << inetSec.GetLastErrorCode(); << endl; 
    return 0; 

if (!inetSec.SendHttpsRequest()) 
    cout << inetSec.GetLastErrorString() << " Code: " 
        << inetSec.GetLastErrorCode(); << endl
    return 0; 

string response = inetSec.GetRequestResult(); 
cout << response.c_str() << endl;

The “organization name” notated functions and variables are completely sample. I chose using “O value of the issuer field” in the certificate, that’s my search criteria. You may wish to perform store search by different fields. Because, there are many fields in a certificate and a context search can be performed by any of these.

You may possibly add your own functions instead of using FindCertWithOUNITName() function. If you do that, just change the code calling this function (only in 1 place) and provide some variables and accessors which are suitable for your certificate search criteria.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


About the Author

Ayhan AVCI
Web Developer
Turkey Turkey
No Biography provided

Comments and Discussions

QuestionPCCERT_CONTEXT PinmemberMember 21652527-May-13 14:09 
BugMEMORY LEAK and HANDLES INCREASING [modified] PinmemberTomice22-Mar-13 3:19 
QuestionPCCERT_CONTEXT global Pinmemberdchris_med19-Mar-12 7:47 
AnswerRe: PCCERT_CONTEXT global Pinmemberdchris_med12-Apr-12 13:14 
GeneralBug: You never actaully set the user name and password PinmemberJimD.999923-Mar-10 5:01 
GeneralSSLV2 instead of SSLV3 Pinmemberagsurfertsi23-Feb-10 11:17 
GeneralRe: SSLV2 instead of SSLV3 PinmemberEricLaw6-Apr-10 10:12 
GeneralWinInet with C++ and Java servlet SSO PinmemberMurali Ch19-Nov-09 1:09 
GeneralError: 12157 on file system NTFS Pinmemberhoogle30-Sep-08 17:35 
If running on the PC using file system FAT 32, it works well.
But if running on the PC using file system is NTFS, it's fail when sending request.
Note: PC OS is Windows XP SP2

int result = HttpSendRequest(m_hRequest, NULL, 0, NULL, 0); //-> fail

GetLastError()-> return error code: 12157
I don't know why?
QuestionError 12029 PinmemberJames Xing12-Aug-07 21:36 
GeneralRe: Error 12029 PinmemberMember 200736623-Apr-08 16:03 
General12044 Pinmemberbhavani bhaskar1-May-07 23:24 
GeneralErrors PinmemberNikhil Trivedi8-Apr-07 23:43 
AnswerRe: Errors Pinmemberpocjoc31-May-07 5:05 
QuestionHow to upload the file Pinmembersaminjesus20-Feb-07 22:31 
AnswerRe: How to upload the file Pinmembersaminjesus21-Feb-07 15:48 
QuestionCan it work on SSL V3 ? Pinmemberzhanglongwei7-Feb-07 16:17 
Generalerror 12045 Pinmembermisz_czu31-Jul-06 1:57 
GeneralRe: error 12045 Pinmembermisz_czu31-Jul-06 21:54 
AnswerRe: error 12045 Pinmemberpocjoc31-May-07 5:00 
Questionhow to solve ERROR_INTERNET_INVALID_CA? Pinmembervictorsh17-May-06 17:19 
AnswerRe: how to solve ERROR_INTERNET_INVALID_CA? Pinmembermisz_czu31-Jul-06 21:54 
GeneralSSL openSSL Pinmemberhbernstein@datavantagecorp.com12-May-06 10:35 
GeneralPost XML request to Secured Server (HTTPS) Pinmembervinodseth4-May-06 5:27 
Questionresponse is 500 !? Pinmemberseayou18-Apr-06 16:25 
Questionhow to implement Client Certificate in without using Winhttp Pinmemberamit@norinn.net5-Oct-05 19:50 
GeneralDeveloping SSL enabled web server for browser as client application PinmemberSushant Patil18-Jul-05 0:41 
GeneralI Can't Complite the Program Pinmemberflexlei19-May-05 16:12 
GeneralRe: I Can't Complite the Program Pinmemberpocjoc31-May-07 5:06 
Generalignore server certificate Pinmemberramfix12-May-05 4:42 
GeneralRe: ignore server certificate Pinmemberramfix12-May-05 5:15 
GeneralError 183 HttpSendRequestEx PinmemberTin Soldier24-Mar-05 9:38 
Generalusername &amp; password instead of certificate Pinmemberssing17-Jan-05 10:12 
GeneralRe: username &amp; password instead of certificate Pinmemberpeebrain@psipog.net22-Oct-05 17:49 
AnswerRe: username &amp; password instead of certificate Pinmemberpocjoc31-May-07 5:01 
GeneralCannot perform http request - Error 12002 PinmemberTomDuffy10-Dec-04 16:33 
GeneralRe: Cannot perform http request - Error 12002 PinmemberAyhan AVCI16-Dec-04 4:23 
GeneralRe: Cannot perform http request - Error 12002 PinmemberTomDuffy22-Dec-04 8:51 
GeneralGENERAL QUERY PinmemberRAGU MANDA17-Nov-04 21:52 
QuestionHow do i create a certificate selection string? Pinmembergeorgezhangca15-Nov-04 8:29 
GeneralHttps request puts ERROR_WINHTTP_CANNOT_CONNECT. PinmemberYasuhiko Yoshimura20-Oct-04 22:43 
GeneralI cannot compile Pinmembersergio766-Sep-04 5:36 
GeneralRe: I cannot compile PinmemberAyhan AVCI14-Sep-04 3:49 
GeneralI am facing the same problem Pinmembercoe.guru21-Jan-05 21:32 
GeneralRe: I am facing the same problem Pinmemberdarren goulston2-Feb-05 6:05 
AnswerRe: I am facing the same problem Pinmembernbk165-Dec-06 5:44 
GeneralCan work under VC6 Pinmemberpeebrain@psipog.net22-Oct-05 17:24 
GeneralRe: I cannot compile PinmemberYves14-Mar-07 12:42 
QuestionHow do I send POST parameters ? PinmemberThierry ICDC8-Jun-04 11:44 
AnswerRe: How do I send POST parameters ? Pinmemberduncan3w3d15-Jul-04 11:12 

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