(Excel) Create XML Digital Signature using Certificate on Smart Card

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Demonstrates how to load a certificate located on a smart card or USB token and then use it for creating an XML digital signature such that the cryptographic signing happens on the smart card.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Note: The ScMinidriver functionality is for Windows-only because ScMinidriver DLLs only exist on Windows. In the next version, Chilkat will be releasing a Pkcs11 class to support Linux, MacOSX, and possibly other operating systems.

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

Dim scmd As Chilkat.ScMinidriver
Set scmd = Chilkat.NewScMinidriver

' Reader names (smart card readers or USB tokens) can be discovered
' via List Readers or Find Smart Cards

readerName = "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"

success = scmd.AcquireContext(readerName)
If (success = False) Then
    Debug.Print scmd.LastErrorText
    Exit Sub
End If

' If successful, the name of the currently inserted smart card is available:
Debug.Print "Card name: "; scmd.CardName

' If desired, perform regular PIN authentication with the smartcard.
' For more details about smart card PIN authentication, see the Smart Card PIN Authentication Example

retval = scmd.PinAuthenticate("user","000000")
If (retval <> 0) Then
    Debug.Print "PIN Authentication failed."
End If

' You can find a cerficate using any of the following certificate parts:
' "subjectDN" -- The full distinguished name of the cert.
' "subjectDN_withTags" -- Same as above, but in a format that includes the subject part tags, such as the "CN=" in "CN=something"
' "subjectCN" -- The common name part (CN) of the certificate's subject.
' "serial" -- The certificate serial number.
' "serial:issuerCN" -- The certificate serial number + the issuer's common name, delimited with a colon char.
' These are the same certificate parts that can be retrieved by listing certificates on the smart card (or USB token).
' See List Certificates on Smart Card Example

certPart = "subjectCN"

partValue = "PIVKey E42D60A759D39147A26E0AF2FB1183C5"

' If the certificate is found, it is loaded into the cert object.
Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert
success = scmd.FindCert(certPart,partValue,cert)
If (success = False) Then
    Debug.Print "Failed to find the certificate."
    Dim success As Boolean
    success = scmd.DeleteContext()
    Exit Sub
End If

Debug.Print "Successfully loaded the cert object from the smart card / USB token."

' Note: When successful, the cert object is internally linked to the ScMinidriver object's authenticated session.
' The cert object can now be used to sign or do other cryptographic operations that occur on the smart card / USB token.
' If your application calls PinDeauthenticate or DeleteContext, the cert will no longer be able to sign on the smart card
' because the smart card ScMinidriver session will no longer be authenticated or deleted.

' ------------------------------------------------------------------------------------------------------------
' We have the certificate.  Now let's do the XML digital signature..

' Create the following XML to be signed:

' <?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>

Dim xml As Chilkat.Xml
Set xml = Chilkat.NewXml
xml.Tag = "SOAP-ENV:Envelope"
success = xml.AddAttribute("xmlns:SOAP-ENV","http://schemas.xmlsoap.org/soap/envelope/")
success = xml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",True,"xmlns:wsse","http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd")
success = xml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",True,"SOAP-ENV:mustUnderstand","1")
success = xml.UpdateAttrAt("SOAP-ENV:Body",True,"xmlns:SOAP-SEC","http://schemas.xmlsoap.org/soap/security/2000-12")
success = xml.UpdateAttrAt("SOAP-ENV:Body",True,"SOAP-SEC:id","Body")
success = xml.UpdateAttrAt("SOAP-ENV:Body|z:FooBar",True,"xmlns:z","http://example.com")

' Prepare for signing...
Dim gen As Chilkat.XmlDSigGen
Set gen = Chilkat.NewXmlDSigGen

' Indicate where the Signature will be inserted.
gen.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"
success = gen.AddSameDocRef("Body","sha1","EXCL_C14N","","")

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

' Note: Our certificate was loaded from the smartcard and is internally linked to the authenticated ScMinidriver session.
' The signing will occur on the smart card using the chosen certificate.

bUsePrivateKey = True
success = gen.SetX509Cert(cert,bUsePrivateKey)
If (success <> True) Then
    Debug.Print gen.LastErrorText
    Exit Sub
End If

' Everything's specified.  Now create and insert the Signature
Dim sbXml As Chilkat.StringBuilder
Set sbXml = Chilkat.NewStringBuilder
success = xml.GetXmlSb(sbXml)
success = gen.CreateXmlDSigSb(sbXml)
If (success <> True) Then
    Debug.Print gen.LastErrorText
    Exit Sub
End If

' Examine the XML with the digital signature inserted
Debug.Print sbXml.GetAsString()

' ------------------------------------------------------------------------------------------------------------
' Cleanup our ScMinidriver session...

' When finished with operations that required authentication, you may if you wish, deauthenticate the session.
success = scmd.PinDeauthenticate("user")
If (success = False) Then
    Debug.Print scmd.LastErrorText
End If

' Delete the context when finished with the card.
success = scmd.DeleteContext()
If (success = False) Then
    Debug.Print scmd.LastErrorText
End If