Tcl Requires Chilkat v11.0.0+
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