(Excel) PKCS11 Find Certificate with Key Usage on Smart Card or USB Token

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Demonstrates how to find and return the 1st certificate on a smart card or USB token with a desired intended key usage.

Note: This example requires Chilkat v9.5.0.91 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

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.
' (A slot is a smart card reader or USB token.)

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

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

' Get the ID of the 1st slot

slotID = json.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.
' 
' If we don't authenticate, then we won't be able to see the private keys, and thus
' we won't know which certificates have an associated private key stored on the smart card.

' The smart card PIN is passed to the Login method.
' userType 1 indicates a "Normal User".

userType = 1

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

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

Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert

' Find a certificate with an intended key usage.
' Possible key usages to find are:
' 
' DigitalSignature
' NonRepudiation
' KeyEncipherment
' DataEncipherment
' CertificateSigning
' CrlSigning
' 
' To find a cert having any one of several usages, pass a comma-separated list of usages:
success = pkcs11.FindCert("keyUsage","NonRepudiation,DigitalSignature",cert)
If (success = True) Then
    Debug.Print "Cert with private key: "; cert.SubjectCN
Else
    Debug.Print "No certificates having the intended key usage were found."
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."