(MFC) Validate Certificate using OCSP Protocol

Demonstrates how to validate a certificate (check the revoked status) using the OCSP protocol.

Note: This example requires Chilkat v9.5.0.75 or greater

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkCert.h>
#include <CkPrng.h>
#include <CkJsonObject.h>
#include <CkBinData.h>
#include <CkHttp.h>
#include <CkHttpResponse.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // Note: Requires Chilkat v9.5.0.75 or greater.

    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This example will check the revoked status of a certificate loaded from a file.
    CkCert cert;
    bool success = cert.LoadFromFile("qa_data/certs/google.crt");
    if (success != true) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the cert's OCSP URL.
    const char *ocspUrl = cert.ocspUrl();

    // Build the JSON that will be the OCSP request.
    CkPrng prng;
    CkJsonObject json;
    json.put_EmitCompact(false);
    json.UpdateString("extensions.ocspNonce",prng.genRandom(36,"base64"));
    json.put_I(0);
    json.UpdateString("request[i].cert.hashAlg","sha1");
    json.UpdateString("request[i].cert.issuerNameHash",cert.hashOf("IssuerDN","sha1","base64"));
    json.UpdateString("request[i].cert.issuerKeyHash",cert.hashOf("IssuerPublicKey","sha1","base64"));
    json.UpdateString("request[i].cert.serialNumber",cert.serialNumber());

    strOut.append(json.emit());
    strOut.append("\r\n");

    // Our OCSP request looks like this:
    // {
    //   "extensions": {
    //     "ocspNonce": "qZDfbpO+nUxRzz6c/SPjE5QCAsPfpkQlRDxTnGl0gnxt7iXO"
    //   },
    //   "request": [
    //     {
    //       "cert": {
    //         "hashAlg": "sha1",
    //         "issuerNameHash": "9u2wY2IygZo19o11oJ0CShGqbK0=",
    //         "issuerKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
    //         "serialNumber": "6175535D87BF94B6"
    //       }
    //     }
    //   ]
    // }

    CkBinData ocspRequest;
    CkHttp http;

    // Convert our JSON to a binary (ASN.1) OCSP request
    http.CreateOcspRequest(json,ocspRequest);

    // Send the OCSP request to the OCSP server
    CkHttpResponse *resp = http.PBinaryBd("POST",ocspUrl,ocspRequest,"application/ocsp-request",false,false);
    if (http.get_LastMethodSuccess() != true) {
        strOut.append(http.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the binary (ASN.1) OCSP reply
    CkBinData ocspReply;
    resp->GetBodyBd(ocspReply);
    delete resp;

    // Convert the binary reply to JSON.
    // Also returns the overall OCSP response status.
    CkJsonObject jsonReply;
    int ocspStatus = http.ParseOcspReply(ocspReply,jsonReply);

    // The ocspStatus can have one of these values:
    // -1:  The ARG1 does not contain a valid OCSP reply.
    // 0:  Successful - Response has valid confirmations..
    // 1: Malformed request - Illegal confirmation request.
    // 2: Internal error - Internal error in issuer.
    // 3: Try later -  Try again later.
    // 4: Not used - This value is never returned.
    // 5: Sig required - Must sign the request.
    // 6: Unauthorized - Request unauthorized.

    if (ocspStatus < 0) {
        strOut.append("Invalid OCSP reply.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Overall OCSP Response Status: ");
    strOut.appendInt(ocspStatus);
    strOut.append("\r\n");

    // Let's examine the OCSP response (in JSON).
    jsonReply.put_EmitCompact(false);
    strOut.append(jsonReply.emit());
    strOut.append("\r\n");

    // The JSON reply looks like this:
    // (Use the online tool at https://tools.chilkat.io/jsonParse.cshtml
    // to generate JSON parsing code.)

    // {
    //   "responseStatus": 0,
    //   "responseTypeOid": "1.3.6.1.5.5.7.48.1.1",
    //   "responseTypeName": "ocspBasic",
    //   "response": {
    //     "responderIdChoice": "KeyHash",
    //     "responderKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
    //     "dateTime": "20180803193937Z",
    //     "cert": [
    //       {
    //         "hashOid": "1.3.14.3.2.26",
    //         "hashAlg": "SHA-1",
    //         "issuerNameHash": "9u2wY2IygZo19o11oJ0CShGqbK0=",
    //         "issuerKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
    //         "serialNumber": "6175535D87BF94B6",
    //         "status": 0,
    //         "thisUpdate": "20180803193937Z",
    //         "nextUpdate": "20180810193937Z"
    //       }
    //     ]
    //   }
    // }
    // 

    // The certificate status:
    int certStatus = jsonReply.IntOf("response.cert[0].status");

    // Possible certStatus values are:
    // 0: Good
    // 1: Revoked
    // 2: Unknown.
    strOut.append("Certificate Status: ");
    strOut.appendInt(certStatus);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }