(MFC) Export a Private Key from an MS Storage Provider

Demonstrates how to export a private key from a Microsoft Storage Provider.

Note: This example requires Chilkat v9.5.0.83 or greater.

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

See Also: Using MFC CString in Chilkat

#include <CkCert.h>
#include <CkPrivateKey.h>
#include <CkKeyContainer.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // This example requires Chilkat v9.5.0.83 or greater.

    // We'll export a certificate's private key from the MS storage provider.
    // It is assumed the certificate + private key is already installed on the Windows system.
    // The export does not remove the key from the Windows storage provider.

    // First, let's get a certificate in one of the many ways we can do it.
    // (I ran certmgr.msc, opened a certificate, and noted it's thumbprint.)
    CkCert cert;
    bool success = cert.LoadByThumbprint("ea5a129c1919a52d238ee28d9f3a8f345b768388","hex");
    if (success == false) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Found: ");
    strOut.append(cert.subjectDN());
    strOut.append("\r\n");

    // First export the private key the easy way.
    CkPrivateKey *privKey = cert.ExportPrivateKey();
    if (cert.get_LastMethodSuccess() == false) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // OK.. we have the private key.  Do whatever we want with it..

    delete privKey;

    // -------------------------------------------------------------
    // Now let's export in a more roundabout way by getting information about the 
    // storage provider and key name and then we'll export completely independent
    // of the certificate.
    // 
    // Remember: The private key is not contained within the certificate.  An X.509 certificate
    // embeds the public key, but the counterpart private key is stored elsewhere, such
    // as in a .pfx/.p12, or as in this case, in the Windows "protected store", or perhaps on
    // a smartcard or hardware token.  (But a private key stored on a smartcard or token cannot
    // be exported.  It must remain on the hardware.)
    // 

    const char *storageProvider = cert.cspName();
    const char *keyName = cert.keyContainerName();

    strOut.append("Information about the certificate's private key:");
    strOut.append("\r\n");
    strOut.append("Storage Provider: ");
    strOut.append(storageProvider);
    strOut.append("\r\n");
    strOut.append("Key Name: ");
    strOut.append(keyName);
    strOut.append("\r\n");

    // Export using just the name of the storage provider and key.
    CkKeyContainer keyCon;
    CkPrivateKey privKey2;
    bool silentFlag = false;
    success = keyCon.ExportKey(keyName,storageProvider,silentFlag,privKey2);
    if (success == false) {
        strOut.append(keyCon.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // OK.. we have the private key in privKey2.  Do whatever we want with it..
    // Perhaps we save as encrypted PKCS8 PEM.
    success = privKey2.SavePkcs8EncryptedPemFile("myPassword","qa_output/privKey2.pem");
    if (success == false) {
        strOut.append(privKey2.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }