C#

Validate Certificate using OCSP Protocol

See more Certificates Examples

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

bool 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.
Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadFromFile("qa_data/certs/google.crt");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

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

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

//  Possible hash algorithms are sha1, sha256, sha384, sha512.  
string hashAlg = "sha256";
Chilkat.Prng prng = new Chilkat.Prng();
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.EmitCompact = false;
//  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);

Debug.WriteLine(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"
//        }
//      }
//    ]
//  }

Chilkat.BinData ocspRequest = new Chilkat.BinData();
Chilkat.Http http = new Chilkat.Http();

//  Convert our JSON to a binary (ASN.1) OCSP request
success = http.CreateOcspRequest(json,ocspRequest);
if (success == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

//  Send the OCSP request to the OCSP server
Chilkat.HttpResponse resp = new Chilkat.HttpResponse();
success = http.HttpBd("POST",ocspUrl,ocspRequest,"application/ocsp-request",resp);
if (success == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

//  Get the binary (ASN.1) OCSP reply
Chilkat.BinData ocspReply = new Chilkat.BinData();
resp.GetBodyBd(ocspReply);

//  Convert the binary reply to JSON.
//  Also returns the overall OCSP response status.
Chilkat.JsonObject jsonReply = new Chilkat.JsonObject();
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) {
    Debug.WriteLine("Invalid OCSP reply.");
    return;
}

Debug.WriteLine("Overall OCSP Response Status: " + Convert.ToString(ocspStatus));

//  Let's examine the OCSP response (in JSON).
jsonReply.EmitCompact = false;
Debug.WriteLine(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:
int certStatus = -1;
if (jsonReply.HasMember("response.cert[0].status") == true) {
    certStatus = jsonReply.IntOf("response.cert[0].status");
}

//  Possible certStatus values are:
//  -1: No status returned.
//  0: Good
//  1: Revoked
//  2: Unknown.
Debug.WriteLine("Certificate Status: " + Convert.ToString(certStatus));