(PureBasic) Get Certificate CRL Distribution Points

Demonstrates how to get a certificate's CRL Distribution Points extension data (assuming it exists). In the vast majority of cases, there will be one CRL Distribution Point.

Note: This example requires Chilkat v9.5.0.76 or greater.

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IncludeFile "CkCert.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkXml.pb"

Procedure ChilkatExample()

    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkCert::ckLoadFromFile(cert,"qa_data/certs/test_haswdt.cer")
    If success <> 1
        Debug CkCert::ckLastErrorText(cert)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ;  Get the CRL Distribution Points extension, which is at OID 2.5.29.31
    extensionXmlStr.s = CkCert::ckGetExtensionAsXml(cert,"2.5.29.31")
    If CkCert::ckLastMethodSuccess(cert) = 0
        Debug "Certificate does not have the CDP extension."
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    xml.i = CkXml::ckCreate()
    If xml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkXml::ckLoadXml(xml,extensionXmlStr)

    ;  See what we have..
    Debug CkXml::ckGetXml(xml)

    ;  We should get XML like this:

    ;  <?xml version="1.0" encoding="utf-8" ?>
    ;  <sequence>
    ;      <sequence>
    ;          <contextSpecific tag="0" constructed="1">
    ;              <contextSpecific tag="0" constructed="1">
    ;                  <contextSpecific tag="6" constructed="0">aHR0cDovL2NybC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1
    ;  cmVFbWFpbENBLmNybA==</contextSpecific>
    ;              </contextSpecific>
    ;          </contextSpecific>
    ;      </sequence>
    ;  </sequence>
    ; 

    ;  Assuming there is one CRL Distribution Point...
    sbDistPoint.i = CkStringBuilder::ckCreate()
    If sbDistPoint.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkXml::ckGetChildContentSb(xml,"sequence|contextSpecific|contextSpecific|contextSpecific",sbDistPoint)
    If success = 1
        CkStringBuilder::ckDecode(sbDistPoint,"base64","utf-8")
        Debug "CRL Distribution Point:  " + CkStringBuilder::ckGetAsString(sbDistPoint)
    EndIf

    ;  Sample output:
    ;  CRL Distribution Point:  http://crl.comodoca.com/COMODORSAClientAuthenticationandSecureEmailCA.crl


    CkCert::ckDispose(cert)
    CkXml::ckDispose(xml)
    CkStringBuilder::ckDispose(sbDistPoint)


    ProcedureReturn
EndProcedure