Delphi ActiveX 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 ActiveX

var
success: Integer;
cert: TChilkatCert;
ocspUrl: WideString;
hashAlg: WideString;
prng: TChilkatPrng;
json: TChilkatJsonObject;
ocspRequest: TChilkatBinData;
http: TChilkatHttp;
resp: TChilkatHttpResponse;
ocspReply: TChilkatBinData;
jsonReply: TChilkatJsonObject;
ocspStatus: Integer;
certStatus: Integer;

begin
success := 0;

//  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 := TChilkatCert.Create(Self);
success := cert.LoadFromFile('qa_data/certs/google.crt');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Get the cert's OCSP URL.
ocspUrl := cert.OcspUrl;

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

//  Possible hash algorithms are sha1, sha256, sha384, sha512.  
hashAlg := 'sha256';
prng := TChilkatPrng.Create(Self);
json := TChilkatJsonObject.Create(Self);
json.EmitCompact := 0;
//  Read more about OCSP nonce lengths
json.UpdateString('extensions.ocspNonce',prng.GenRandom(16,'base64'));
json.I := 0;
json.UpdateString('request[i].cert.hashAlg',hashAlg);
json.UpdateString('request[i].cert.issuerNameHash',cert.HashOf('IssuerDN',hashAlg,'base64'));
json.UpdateString('request[i].cert.issuerKeyHash',cert.HashOf('IssuerPublicKey',hashAlg,'base64'));
json.UpdateString('request[i].cert.serialNumber',cert.SerialNumber);

Memo1.Lines.Add(json.Emit());

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

ocspRequest := TChilkatBinData.Create(Self);
http := TChilkatHttp.Create(Self);

//  Convert our JSON to a binary (ASN.1) OCSP request
success := http.CreateOcspRequest(json.ControlInterface,ocspRequest.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

//  Send the OCSP request to the OCSP server
resp := TChilkatHttpResponse.Create(Self);
success := http.HttpBd('POST',ocspUrl,ocspRequest.ControlInterface,'application/ocsp-request',resp.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

//  Get the binary (ASN.1) OCSP reply
ocspReply := TChilkatBinData.Create(Self);
resp.GetBodyBd(ocspReply.ControlInterface);

//  Convert the binary reply to JSON.
//  Also returns the overall OCSP response status.
jsonReply := TChilkatJsonObject.Create(Self);
ocspStatus := http.ParseOcspReply(ocspReply.ControlInterface,jsonReply.ControlInterface);

//  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).
jsonReply.EmitCompact := 0;
Memo1.Lines.Add(jsonReply.Emit());

//  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 (jsonReply.HasMember('response.cert[0].status') = 1) then
  begin
    certStatus := jsonReply.IntOf('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));