(C) Validate Certificate using OCSP Protocol

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

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#include <C_CkCert.h>
#include <C_CkPrng.h>
#include <C_CkJsonObject.h>
#include <C_CkBinData.h>
#include <C_CkHttp.h>
#include <C_CkHttpResponse.h>

void ChilkatSample(void)
    {
    HCkCert cert;
    BOOL success;
    const char *ocspUrl;
    const char *hashAlg;
    HCkPrng prng;
    HCkJsonObject json;
    HCkBinData ocspRequest;
    HCkHttp http;
    HCkHttpResponse resp;
    HCkBinData ocspReply;
    HCkJsonObject jsonReply;
    int ocspStatus;
    int certStatus;

    // 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.
    cert = CkCert_Create();
    success = CkCert_LoadFromFile(cert,"qa_data/certs/google.crt");
    if (success != TRUE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCert_Dispose(cert);
        return;
    }

    // Get the cert's OCSP URL.
    ocspUrl = CkCert_ocspUrl(cert);

    // Build the JSON that will be the OCSP request.

    // Possible hash algorithms are sha1, sha256, sha384, sha512.  
    hashAlg = "sha256";
    prng = CkPrng_Create();
    json = CkJsonObject_Create();
    CkJsonObject_putEmitCompact(json,FALSE);
    // Read more about OCSP nonce lengths
    CkJsonObject_UpdateString(json,"extensions.ocspNonce",CkPrng_genRandom(prng,16,"base64"));
    CkJsonObject_putI(json,0);
    CkJsonObject_UpdateString(json,"request[i].cert.hashAlg",hashAlg);
    CkJsonObject_UpdateString(json,"request[i].cert.issuerNameHash",CkCert_hashOf(cert,"IssuerDN",hashAlg,"base64"));
    CkJsonObject_UpdateString(json,"request[i].cert.issuerKeyHash",CkCert_hashOf(cert,"IssuerPublicKey",hashAlg,"base64"));
    CkJsonObject_UpdateString(json,"request[i].cert.serialNumber",CkCert_serialNumber(cert));

    printf("%s\n",CkJsonObject_emit(json));

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

    ocspRequest = CkBinData_Create();
    http = CkHttp_Create();

    // Convert our JSON to a binary (ASN.1) OCSP request
    success = CkHttp_CreateOcspRequest(http,json,ocspRequest);
    if (success == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkCert_Dispose(cert);
        CkPrng_Dispose(prng);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(ocspRequest);
        CkHttp_Dispose(http);
        return;
    }

    // Send the OCSP request to the OCSP server
    resp = CkHttp_PBinaryBd(http,"POST",ocspUrl,ocspRequest,"application/ocsp-request",FALSE,FALSE);
    if (CkHttp_getLastMethodSuccess(http) != TRUE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkCert_Dispose(cert);
        CkPrng_Dispose(prng);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(ocspRequest);
        CkHttp_Dispose(http);
        return;
    }

    // Get the binary (ASN.1) OCSP reply
    ocspReply = CkBinData_Create();
    CkHttpResponse_GetBodyBd(resp,ocspReply);
    CkHttpResponse_Dispose(resp);

    // Convert the binary reply to JSON.
    // Also returns the overall OCSP response status.
    jsonReply = CkJsonObject_Create();
    ocspStatus = CkHttp_ParseOcspReply(http,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) {
        printf("Invalid OCSP reply.\n");
        CkCert_Dispose(cert);
        CkPrng_Dispose(prng);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(ocspRequest);
        CkHttp_Dispose(http);
        CkBinData_Dispose(ocspReply);
        CkJsonObject_Dispose(jsonReply);
        return;
    }

    printf("Overall OCSP Response Status: %d\n",ocspStatus);

    // Let's examine the OCSP response (in JSON).
    CkJsonObject_putEmitCompact(jsonReply,FALSE);
    printf("%s\n",CkJsonObject_emit(jsonReply));

    // 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:
    certStatus = -1;
    if (CkJsonObject_HasMember(jsonReply,"response.cert[0].status") == TRUE) {
        certStatus = CkJsonObject_IntOf(jsonReply,"response.cert[0].status");
    }

    // Possible certStatus values are:
    // -1: No status returned.
    // 0: Good
    // 1: Revoked
    // 2: Unknown.
    printf("Certificate Status: %d\n",certStatus);


    CkCert_Dispose(cert);
    CkPrng_Dispose(prng);
    CkJsonObject_Dispose(json);
    CkBinData_Dispose(ocspRequest);
    CkHttp_Dispose(http);
    CkBinData_Dispose(ocspReply);
    CkJsonObject_Dispose(jsonReply);

    }