(Visual FoxPro) 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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LOCAL loPkcs11
LOCAL lnUserType
LOCAL lcPin
LOCAL lnSuccess
LOCAL loCert
LOCAL loXml
LOCAL loGen
LOCAL lnBUsePrivateKey
LOCAL loSbXml

* 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.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Pkcs11')
loPkcs11 = CreateObject('Chilkat.Pkcs11')

* 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.
loPkcs11.SharedLibPath = "aetpkss1.dll"

* Make it an authenticated session by calling Login.
lnUserType = 1
* Make sure to use the correct PIN for your smart card..
lcPin = "0000"

lnSuccess = loPkcs11.QuickSession(lnUserType,lcPin)
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    CANCEL
ENDIF

* Get the certificate (on the smart card) that has a private key.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loPkcs11.FindCert("privateKey","",loCert)
IF (lnSuccess = 1) THEN
    ? "Cert with private key: " + loCert.SubjectCN
ELSE
    ? "No certificates having a private key were found."
    lnSuccess = loPkcs11.CloseSession()
    RELEASE loPkcs11
    RELEASE loCert
    CANCEL
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>

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Xml')
loXml = CreateObject('Chilkat.Xml')
loXml.Tag = "SOAP-ENV:Envelope"
loXml.AddAttribute("xmlns:SOAP-ENV","http://schemas.xmlsoap.org/soap/envelope/")
loXml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",1,"xmlns:wsse","http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd")
loXml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",1,"SOAP-ENV:mustUnderstand","1")
loXml.UpdateAttrAt("SOAP-ENV:Body",1,"xmlns:SOAP-SEC","http://schemas.xmlsoap.org/soap/security/2000-12")
loXml.UpdateAttrAt("SOAP-ENV:Body",1,"SOAP-SEC:id","Body")
loXml.UpdateAttrAt("SOAP-ENV:Body|z:FooBar",1,"xmlns:z","http://example.com")

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.XmlDSigGen')
loGen = CreateObject('Chilkat.XmlDSigGen')

* Indicate where the Signature will be inserted.
loGen.SigLocation = "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"
loGen.AddSameDocRef("Body","sha1","EXCL_C14N","","")

* (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
loGen.SignedInfoPrefixList = "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.
loGen.KeyInfoType = "X509Data"
loGen.X509Type = "Certificate"

lnBUsePrivateKey = 1
lnSuccess = loGen.SetX509Cert(loCert,lnBUsePrivateKey)
IF (lnSuccess <> 1) THEN
    ? loGen.LastErrorText
    lnSuccess = loPkcs11.CloseSession()
    RELEASE loPkcs11
    RELEASE loCert
    RELEASE loXml
    RELEASE loGen
    CANCEL
ENDIF

* Everything's specified.  Now create and insert the Signature
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbXml = CreateObject('Chilkat.StringBuilder')
loXml.EmitCompact = 1
loXml.GetXmlSb(loSbXml)

lnSuccess = loGen.CreateXmlDSigSb(loSbXml)
IF (lnSuccess <> 1) THEN
    ? loGen.LastErrorText
    lnSuccess = loPkcs11.CloseSession()
    RELEASE loPkcs11
    RELEASE loCert
    RELEASE loXml
    RELEASE loGen
    RELEASE loSbXml
    CANCEL
ENDIF

* Examine the XML with the digital signature inserted
? loSbXml.GetAsString()

* --------------------------------------------------------------------------

* Revert to an unauthenticated session by calling Logout.
lnSuccess = loPkcs11.Logout()
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    lnSuccess = loPkcs11.CloseSession()
    RELEASE loPkcs11
    RELEASE loCert
    RELEASE loXml
    RELEASE loGen
    RELEASE loSbXml
    CANCEL
ENDIF

* When finished, close the session.
* It is important to close the session (memory leaks will occur if the session is not properly closed).
lnSuccess = loPkcs11.CloseSession()
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    RELEASE loCert
    RELEASE loXml
    RELEASE loGen
    RELEASE loSbXml
    CANCEL
ENDIF

? "Success."

RELEASE loPkcs11
RELEASE loCert
RELEASE loXml
RELEASE loGen
RELEASE loSbXml