Chilkat2-Python

Validate Certificate using OCSP Protocol

See more Certificates Examples

Demonstrates how to validate a certificate (check the revoked status) using the OCSP protocol. Chilkat2-Python

import sys
import chilkat2

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 = chilkat2.Cert()
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 = chilkat2.Prng()
json = chilkat2.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)

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 = chilkat2.BinData()
http = chilkat2.Http()

# 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 = chilkat2.HttpResponse()
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 = chilkat2.BinData()
resp.GetBodyBd(ocspReply)

# Convert the binary reply to JSON.
# Also returns the overall OCSP response status.
jsonReply = chilkat2.JsonObject()
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.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))