Tcl
Validate Certificate using OCSP Protocol

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

Tcl

load ./chilkat.dll

set 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.
set cert [new_CkCert]

set success [CkCert_LoadFromFile $cert "qa_data/certs/google.crt"]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkCert $cert
    exit
}

# Get the cert's OCSP URL.
set ocspUrl [CkCert_ocspUrl $cert]

# Build the JSON that will be the OCSP request.

# Possible hash algorithms are sha1, sha256, sha384, sha512.  
set hashAlg "sha256"
set prng [new_CkPrng]

set json [new_CkJsonObject]

CkJsonObject_put_EmitCompact $json 0
# Read more about OCSP nonce lengths
CkJsonObject_UpdateString $json "extensions.ocspNonce" [CkPrng_genRandom $prng 16 "base64"]
CkJsonObject_put_I $json 0
CkJsonObject_UpdateString $json "request[i].cert.hashAlg" $hashAlg
CkJsonObject_UpdateString $json "request[i].cert.issuerNameHash" [CkCert_hashOf $cert "IssuerDN" $hashAlg "base64"]
CkJsonObject_UpdateString $json "request[i].cert.issuerKeyHash" [CkCert_hashOf $cert "IssuerPublicKey" $hashAlg "base64"]
CkJsonObject_UpdateString $json "request[i].cert.serialNumber" [CkCert_serialNumber $cert]

puts [CkJsonObject_emit $json]

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

set ocspRequest [new_CkBinData]

set http [new_CkHttp]

# Convert our JSON to a binary (ASN.1) OCSP request
set success [CkHttp_CreateOcspRequest $http $json $ocspRequest]
if {$success == 0} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkCert $cert
    delete_CkPrng $prng
    delete_CkJsonObject $json
    delete_CkBinData $ocspRequest
    delete_CkHttp $http
    exit
}

# Send the OCSP request to the OCSP server
set resp [new_CkHttpResponse]

set success [CkHttp_HttpBd $http "POST" $ocspUrl $ocspRequest "application/ocsp-request" $resp]
if {$success == 0} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkCert $cert
    delete_CkPrng $prng
    delete_CkJsonObject $json
    delete_CkBinData $ocspRequest
    delete_CkHttp $http
    delete_CkHttpResponse $resp
    exit
}

# Get the binary (ASN.1) OCSP reply
set ocspReply [new_CkBinData]

CkHttpResponse_GetBodyBd $resp $ocspReply

# Convert the binary reply to JSON.
# Also returns the overall OCSP response status.
set jsonReply [new_CkJsonObject]

set ocspStatus [CkHttp_ParseOcspReply $http $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} then {
    puts "Invalid OCSP reply."
    delete_CkCert $cert
    delete_CkPrng $prng
    delete_CkJsonObject $json
    delete_CkBinData $ocspRequest
    delete_CkHttp $http
    delete_CkHttpResponse $resp
    delete_CkBinData $ocspReply
    delete_CkJsonObject $jsonReply
    exit
}

puts "Overall OCSP Response Status: $ocspStatus"

# Let's examine the OCSP response (in JSON).
CkJsonObject_put_EmitCompact $jsonReply 0
puts [CkJsonObject_emit $jsonReply]

# 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:
set certStatus -1
if {[CkJsonObject_HasMember $jsonReply "response.cert[0].status"] == 1} then {
    set certStatus [CkJsonObject_IntOf $jsonReply "response.cert[0].status"]
}

# Possible certStatus values are:
# -1: No status returned.
# 0: Good
# 1: Revoked
# 2: Unknown.
puts "Certificate Status: $certStatus"

delete_CkCert $cert
delete_CkPrng $prng
delete_CkJsonObject $json
delete_CkBinData $ocspRequest
delete_CkHttp $http
delete_CkHttpResponse $resp
delete_CkBinData $ocspReply
delete_CkJsonObject $jsonReply