(MFC) 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.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkPkcs11.h>
#include <CkJsonObject.h>
#include <CkCert.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // 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.

    CkPkcs11 pkcs11;

    pkcs11.put_SharedLibPath("aetpkss1.dll");

    bool success = pkcs11.Initialize();
    if (success == false) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // We need to call Discover to get the slot ID.
    // (A slot is a smart card reader or USB token.)
    bool onlyTokensPresent = true;
    CkJsonObject json;
    success = pkcs11.Discover(onlyTokensPresent,json);
    if (success == false) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Make sure we have at least one slot.
    if (json.SizeOfArray("slot") <= 0) {
        strOut.append("No occuplied slots.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the ID of the 1st slot
    int slotID = json.IntOf("slot[0].id");

    // Open a session.
    bool readWrite = true;
    success = pkcs11.OpenSession(slotID,readWrite);
    if (success == false) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // 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".
    int userType = 1;
    const char *pin = "0000";
    success = pkcs11.Login(userType,pin);
    if (success == false) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        success = pkcs11.CloseSession();
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // --------------------------------------------------------------------------

    CkCert 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:
    success = pkcs11.FindCert("keyUsage","NonRepudiation,DigitalSignature",cert);
    if (success == true) {
        strOut.append("Cert with private key: ");
        strOut.append(cert.subjectCN());
        strOut.append("\r\n");
    }
    else {
        strOut.append("No certificates having the intended key usage were found.");
        strOut.append("\r\n");
    }

    // --------------------------------------------------------------------------

    // Revert to an unauthenticated session by calling Logout.
    success = pkcs11.Logout();
    if (success == false) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        success = pkcs11.CloseSession();
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // 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) {
        strOut.append(pkcs11.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Success.");
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }