(Lianja) Validate Certificate using OCSP Protocol

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

Chilkat Lianja Extension Download Chilkat Lianja Extension

// 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.
loCert = createobject("CkCert")
llSuccess = loCert.LoadFromFile("qa_data/certs/google.crt")
if (llSuccess <> .T.) then
    ? loCert.LastErrorText
    release loCert
    return
endif

// Get the cert's OCSP URL.
lcOcspUrl = loCert.OcspUrl

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

// Possible hash algorithms are sha1, sha256, sha384, sha512.  
lcHashAlg = "sha256"
loPrng = createobject("CkPrng")
loJson = createobject("CkJsonObject")
loJson.EmitCompact = .F.
// Read more about OCSP nonce lengths
loJson.UpdateString("extensions.ocspNonce",loPrng.GenRandom(16,"base64"))
loJson.I = 0
loJson.UpdateString("request[i].cert.hashAlg",lcHashAlg)
loJson.UpdateString("request[i].cert.issuerNameHash",loCert.HashOf("IssuerDN",lcHashAlg,"base64"))
loJson.UpdateString("request[i].cert.issuerKeyHash",loCert.HashOf("IssuerPublicKey",lcHashAlg,"base64"))
loJson.UpdateString("request[i].cert.serialNumber",loCert.SerialNumber)

? loJson.Emit()

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

loOcspRequest = createobject("CkBinData")
loHttp = createobject("CkHttp")

// Convert our JSON to a binary (ASN.1) OCSP request
llSuccess = loHttp.CreateOcspRequest(loJson,loOcspRequest)
if (llSuccess = .F.) then
    ? loHttp.LastErrorText
    release loCert
    release loPrng
    release loJson
    release loOcspRequest
    release loHttp
    return
endif

// Send the OCSP request to the OCSP server
loResp = loHttp.PBinaryBd("POST",lcOcspUrl,loOcspRequest,"application/ocsp-request",.F.,.F.)
if (loHttp.LastMethodSuccess <> .T.) then
    ? loHttp.LastErrorText
    release loCert
    release loPrng
    release loJson
    release loOcspRequest
    release loHttp
    return
endif

// Get the binary (ASN.1) OCSP reply
loOcspReply = createobject("CkBinData")
loResp.GetBodyBd(loOcspReply)
release loResp

// Convert the binary reply to JSON.
// Also returns the overall OCSP response status.
loJsonReply = createobject("CkJsonObject")
lnOcspStatus = loHttp.ParseOcspReply(loOcspReply,loJsonReply)

// 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 (lnOcspStatus < 0) then
    ? "Invalid OCSP reply."
    release loCert
    release loPrng
    release loJson
    release loOcspRequest
    release loHttp
    release loOcspReply
    release loJsonReply
    return
endif

? "Overall OCSP Response Status: " + str(lnOcspStatus)

// Let's examine the OCSP response (in JSON).
loJsonReply.EmitCompact = .F.
? loJsonReply.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:
lnCertStatus = -1
if (loJsonReply.HasMember("response.cert[0].status") = .T.) then
    lnCertStatus = loJsonReply.IntOf("response.cert[0].status")
endif

// Possible certStatus values are:
// -1: No status returned.
// 0: Good
// 1: Revoked
// 2: Unknown.
? "Certificate Status: " + str(lnCertStatus)


release loCert
release loPrng
release loJson
release loOcspRequest
release loHttp
release loOcspReply
release loJsonReply