Delphi DLL Requires Chilkat v11.0.0+

Validate Certificate using OCSP Protocol

See more Certificates Examples

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

var
success: Boolean;
cert: HCkCert;
ocspUrl: PWideChar;
hashAlg: PWideChar;
prng: HCkPrng;
json: HCkJsonObject;
ocspRequest: HCkBinData;
http: HCkHttp;
resp: HCkHttpResponse;
ocspReply: HCkBinData;
jsonReply: HCkJsonObject;
ocspStatus: Integer;
certStatus: Integer;

begin
success := False;

//  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 = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    Exit;
  end;

//  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));

Memo1.Lines.Add(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) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

//  Send the OCSP request to the OCSP server
resp := CkHttpResponse_Create();
success := CkHttp_HttpBd(http,'POST',ocspUrl,ocspRequest,'application/ocsp-request',resp);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

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

//  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) then
  begin
    Memo1.Lines.Add('Invalid OCSP reply.');
    Exit;
  end;

Memo1.Lines.Add('Overall OCSP Response Status: ' + IntToStr(ocspStatus));

//  Let's examine the OCSP response (in JSON).
CkJsonObject_putEmitCompact(jsonReply,False);
Memo1.Lines.Add(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) then
  begin
    certStatus := CkJsonObject_IntOf(jsonReply,'response.cert[0].status');
  end;

//  Possible certStatus values are:
//  -1: No status returned.
//  0: Good
//  1: Revoked
//  2: Unknown.
Memo1.Lines.Add('Certificate Status: ' + IntToStr(certStatus));

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