CkPython 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. CkPython

import sys
import chilkat

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 = chilkat.CkCert()
success = cert.LoadFromFile("qa_data/certs/google.crt")
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

#  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 = chilkat.CkPrng()
json = chilkat.CkJsonObject()
json.put_EmitCompact(False)
#  Read more about OCSP nonce lengths
json.UpdateString("extensions.ocspNonce",prng.genRandom(16,"base64"))
json.put_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())

print(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 = chilkat.CkBinData()
http = chilkat.CkHttp()

#  Convert our JSON to a binary (ASN.1) OCSP request
success = http.CreateOcspRequest(json,ocspRequest)
if (success == False):
    print(http.lastErrorText())
    sys.exit()

#  Send the OCSP request to the OCSP server
resp = chilkat.CkHttpResponse()
success = http.HttpBd("POST",ocspUrl,ocspRequest,"application/ocsp-request",resp)
if (success == False):
    print(http.lastErrorText())
    sys.exit()

#  Get the binary (ASN.1) OCSP reply
ocspReply = chilkat.CkBinData()
resp.GetBodyBd(ocspReply)

#  Convert the binary reply to JSON.
#  Also returns the overall OCSP response status.
jsonReply = chilkat.CkJsonObject()
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):
    print("Invalid OCSP reply.")
    sys.exit()

print("Overall OCSP Response Status: " + str(ocspStatus))

#  Let's examine the OCSP response (in JSON).
jsonReply.put_EmitCompact(False)
print(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") == True):
    certStatus = jsonReply.IntOf("response.cert[0].status")

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