(Excel) PKCS11 Sign PDF using Certificate and Private Key on Smart Card / USB Token

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Sample code showing how to use PKCS11 to sign a PDF with a certificate and private key stored on a smart card or USB token.

Note: This example requires Chilkat v9.5.0.88 or later.

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' 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.

Dim pkcs11 As Chilkat.Pkcs11
Set pkcs11 = Chilkat.NewPkcs11

' This example is tested on Windows using a Giesecke and Devrient Sm@rtCafe Expert 3.2 smart card.
pkcs11.SharedLibPath = "aetpkss1.dll"


success = pkcs11.Initialize()
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    Exit Sub
End If

' We need to call Discover to get the slot ID.

onlyTokensPresent = True
Dim jsonPkcs11 As Chilkat.JsonObject
Set jsonPkcs11 = Chilkat.NewJsonObject
success = pkcs11.Discover(onlyTokensPresent,jsonPkcs11)
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    Exit Sub
End If

' Make sure we have at least one slot.
If (jsonPkcs11.SizeOfArray("slot") <= 0) Then
    Debug.Print "No occuplied slots."
    Exit Sub
End If

' Get the ID of the 1st slot

slotID = jsonPkcs11.IntOf("slot[0].id")

' Open a session.

readWrite = True
success = pkcs11.OpenSession(slotID,readWrite)
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    Exit Sub
End If

' Make it an authenticated session by calling Login.

userType = 1
' Make sure to use the correct PIN for your smart card..

pin = "0000"
success = pkcs11.Login(userType,pin)
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    success = pkcs11.CloseSession()
    Exit Sub
End If

' Get the certificate (on the smart card) that has a private key.
Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert
success = pkcs11.FindCert("privateKey","",cert)
If (success = True) Then
    Debug.Print "Cert with private key: "; cert.SubjectCN
Else
    Debug.Print "No certificates having a private key were found."
    success = pkcs11.CloseSession()
    Exit Sub
End If

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

Dim pdf As Chilkat.Pdf
Set pdf = Chilkat.NewPdf

' Load a PDF to be signed.
success = pdf.LoadFile("qa_data/pdf/hello.pdf")
If (success = False) Then
    Debug.Print pdf.LastErrorText
    success = pkcs11.CloseSession()
    Exit Sub
End If

Dim json As Chilkat.JsonObject
Set json = Chilkat.NewJsonObject

Dim success As Boolean
success = json.UpdateInt("page",1)
success = json.UpdateString("appearance.y","top")
success = json.UpdateString("appearance.x","left")
success = json.UpdateString("appearance.fontScale","10.0")
success = json.UpdateString("signingAlgorithm","pss")
success = json.UpdateString("hashAlgorithm","sha256")


i = 0
json.I = i
success = json.UpdateString("appearance.text[i]","Digitaly signed by: Xyz Widgets, Inc.")
i = i + 1
json.I = i
success = json.UpdateString("appearance.text[i]","current_dt")
i = i + 1
json.I = i
success = json.UpdateString("appearance.text[i]","blah blah blah")

' The certificate is internally linked to the Pkcs11 object, which is currently in an authenticated session.
success = pdf.SetSigningCert(cert)

success = pdf.SignPdf(json,"qa_output/out.pdf")
If (success = False) Then
    Debug.Print pdf.LastErrorText
    success = pkcs11.CloseSession()
    Exit Sub
End If

' --------------------------------------------------------------------------

' Revert to an unauthenticated session by calling Logout.
success = pkcs11.Logout()
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    success = pkcs11.CloseSession()
    Exit Sub
End If

' When finished, close the session.
' It is important to close the session (memory leaks will occur if the session is not properly closed).
success = pkcs11.CloseSession()
If (success = False) Then
    Debug.Print pkcs11.LastErrorText
    Exit Sub
End If

Debug.Print "Success."