(Visual FoxPro) 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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LOCAL loPkcs11
LOCAL lnSuccess
LOCAL lnSlotID
LOCAL lnReadWrite
LOCAL lnUserType
LOCAL lcPin
LOCAL loCert

* 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')

loPkcs11.SharedLibPath = "aetpkss1.dll"

lnSuccess = loPkcs11.Initialize()
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    CANCEL
ENDIF

* Pass -1 for the slotID to open a session on the first non-empty slot.
lnSlotID = -1

* Open a session.
lnReadWrite = 1
lnSuccess = loPkcs11.OpenSession(lnSlotID,lnReadWrite)
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    RELEASE loPkcs11
    CANCEL
ENDIF

* 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".
lnUserType = 1
lcPin = "0000"
lnSuccess = loPkcs11.Login(lnUserType,lcPin)
IF (lnSuccess = 0) THEN
    ? loPkcs11.LastErrorText
    lnSuccess = loPkcs11.CloseSession()
    RELEASE loPkcs11
    CANCEL
ENDIF

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

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

* 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:
lnSuccess = loPkcs11.FindCert("keyUsage","NonRepudiation,DigitalSignature",loCert)
IF (lnSuccess = 1) THEN
    ? "Cert with private key: " + loCert.SubjectCN
ELSE
    ? "No certificates having the intended key usage were found."
ENDIF

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

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

? "Success."

RELEASE loPkcs11
RELEASE loCert