(PureBasic) PKCS11 XML Signature using Certificate and Private Key on Smart Card / USB Token

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Sample code showing how to use PKCS11 to create an XML digital signature with a certificate and private key stored on a smart card or USB token.

Note: This example requires Chilkat v9.5.0.96 or later.

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IncludeFile "CkPkcs11.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkXmlDSigGen.pb"
IncludeFile "CkXml.pb"
IncludeFile "CkStringBuilder.pb"

Procedure ChilkatExample()

    ; This example requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    ; Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

    pkcs11.i = CkPkcs11::ckCreate()
    If pkcs11.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; This example is tested on Windows using a Giesecke and Devrient Sm@rtCafe Expert 3.2 smart card.
    ; You will use the DLL (or shared lib) provided by your smart card vendor, or a DLL compatible with your smart card.
    ; On Windows, if the DLL is located in C:\Windows\System32, specify only the filename.
    ; Otherwise provide the full path.
    CkPkcs11::setCkSharedLibPath(pkcs11, "aetpkss1.dll")

    ; Make it an authenticated session by calling Login.
    userType.i = 1
    ; Make sure to use the correct PIN for your smart card..
    pin.s = "0000"

    success.i = CkPkcs11::ckQuickSession(pkcs11,userType,pin)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        ProcedureReturn
    EndIf

    ; Get the certificate (on the smart card) that has a private key.
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPkcs11::ckFindCert(pkcs11,"privateKey","",cert)
    If success = 1
        Debug "Cert with private key: " + CkCert::ckSubjectCN(cert)
    Else
        Debug "No certificates having a private key were found."
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; --------------------------------------------------------------------------
    ; At this point, we have the cert to be used for signing.
    ; Our XML signing code is the same as for a cert obtained from any other source..

    ; First generate the following XML to be signed:
    ; Use this online tool to generate code from sample XML: 
    ; Generate Code to Create XML

    ; <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
    ; <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
    ;     <SOAP-ENV:Header>
    ;         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1"></wsse:Security>
    ;     </SOAP-ENV:Header>
    ;     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
    ;         <z:FooBar xmlns:z="http://example.com" />
    ;     </SOAP-ENV:Body>
    ; </SOAP-ENV:Envelope>

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

    CkXml::setCkTag(xml, "SOAP-ENV:Envelope")
    CkXml::ckAddAttribute(xml,"xmlns:SOAP-ENV","http://schemas.xmlsoap.org/soap/envelope/")
    CkXml::ckUpdateAttrAt(xml,"SOAP-ENV:Header|wsse:Security",1,"xmlns:wsse","http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd")
    CkXml::ckUpdateAttrAt(xml,"SOAP-ENV:Header|wsse:Security",1,"SOAP-ENV:mustUnderstand","1")
    CkXml::ckUpdateAttrAt(xml,"SOAP-ENV:Body",1,"xmlns:SOAP-SEC","http://schemas.xmlsoap.org/soap/security/2000-12")
    CkXml::ckUpdateAttrAt(xml,"SOAP-ENV:Body",1,"SOAP-SEC:id","Body")
    CkXml::ckUpdateAttrAt(xml,"SOAP-ENV:Body|z:FooBar",1,"xmlns:z","http://example.com")

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

    ; Indicate where the Signature will be inserted.
    CkXmlDSigGen::setCkSigLocation(gen, "SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security")

    ; Add a reference to the fragment of the XML to be signed.

    ; Note: "Body" refers to the XML element having an "id" equal to "Body", where "id" is case insensitive
    ; and where any namespace might qualify the attribute.  In this case, the SOAP-ENV:Body fragment is signed
    ; NOT because the tag = "Body", but because it has SOAP-SEC:id="Body"
    CkXmlDSigGen::ckAddSameDocRef(gen,"Body","sha1","EXCL_C14N","","")

    ; (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
    CkXmlDSigGen::setCkSignedInfoPrefixList(gen, "wsse SOAP-ENV")

    ; Provide the private key for signing via the certificate, and indicate that
    ; we want the base64 of the certificate embedded in the KeyInfo.
    CkXmlDSigGen::setCkKeyInfoType(gen, "X509Data")
    CkXmlDSigGen::setCkX509Type(gen, "Certificate")

    bUsePrivateKey.i = 1
    success = CkXmlDSigGen::ckSetX509Cert(gen,cert,bUsePrivateKey)
    If success <> 1
        Debug CkXmlDSigGen::ckLastErrorText(gen)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkXml::ckDispose(xml)
        CkXmlDSigGen::ckDispose(gen)
        ProcedureReturn
    EndIf

    ; Everything's specified.  Now create and insert the Signature
    sbXml.i = CkStringBuilder::ckCreate()
    If sbXml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkXml::setCkEmitCompact(xml, 1)
    CkXml::ckGetXmlSb(xml,sbXml)

    success = CkXmlDSigGen::ckCreateXmlDSigSb(gen,sbXml)
    If success <> 1
        Debug CkXmlDSigGen::ckLastErrorText(gen)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkXml::ckDispose(xml)
        CkXmlDSigGen::ckDispose(gen)
        CkStringBuilder::ckDispose(sbXml)
        ProcedureReturn
    EndIf

    ; Examine the XML with the digital signature inserted
    Debug CkStringBuilder::ckGetAsString(sbXml)

    ; --------------------------------------------------------------------------

    ; Revert to an unauthenticated session by calling Logout.
    success = CkPkcs11::ckLogout(pkcs11)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        success = CkPkcs11::ckCloseSession(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkXml::ckDispose(xml)
        CkXmlDSigGen::ckDispose(gen)
        CkStringBuilder::ckDispose(sbXml)
        ProcedureReturn
    EndIf

    ; When finished, close the session.
    ; It is important to close the session (memory leaks will occur if the session is not properly closed).
    success = CkPkcs11::ckCloseSession(pkcs11)
    If success = 0
        Debug CkPkcs11::ckLastErrorText(pkcs11)
        CkPkcs11::ckDispose(pkcs11)
        CkCert::ckDispose(cert)
        CkXml::ckDispose(xml)
        CkXmlDSigGen::ckDispose(gen)
        CkStringBuilder::ckDispose(sbXml)
        ProcedureReturn
    EndIf

    Debug "Success."


    CkPkcs11::ckDispose(pkcs11)
    CkCert::ckDispose(cert)
    CkXml::ckDispose(xml)
    CkXmlDSigGen::ckDispose(gen)
    CkStringBuilder::ckDispose(sbXml)


    ProcedureReturn
EndProcedure