(MFC) RSA Sign String using Private Key of Certificate Type A3 (smart card / token)

Demonstrates RSA signing a string using the private key of a certificate type A3 (smart card, token).

Note: This is a Windows-only example.

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

See Also: Using MFC CString in Chilkat

#include <CkCertStore.h>
#include <CkCert.h>
#include <CkRsa.h>

void ChilkatSample(void)
    {
    CkString strOut;

    //  First get the A3 certificate that was installed on the Windows system.
    CkCertStore certStore;

    const char *thumbprint = "12c1dd8015f3f03f7b1fa619dc24e2493ca8b4b2";

    //  This is specific to Windows because it is opening the Windows Current-User certificate store.
    bool bReadOnly = true;
    bool success = certStore.OpenCurrentUserStore(bReadOnly);
    if (success != true) {
        strOut.append(certStore.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    //  Find the certificate with the desired thumbprint
    //  (There are many ways to locate a certificate.  This example chooses to find by thumbprint.)
    CkCert *cert = certStore.FindCertBySha1Thumbprint(thumbprint);
    if (certStore.get_LastMethodSuccess() != true) {
        strOut.append("Failed to find the certificate.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Found: ");
    strOut.append(cert->subjectCN());
    strOut.append("\r\n");

    CkRsa rsa;

    //  Provide the cert's private key
    bool bUsePrivateKey = true;
    success = rsa.SetX509Cert(*cert,bUsePrivateKey);
    delete cert;
    if (success != true) {
        strOut.append(rsa.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    //  Return the RSA signature in base64 encoded form.
    rsa.put_EncodingMode("base64");

    //  Sign the utf-8 byte representation of the string.
    rsa.put_Charset("utf-8");

    //  You can also choose other hash algorithms, such as SHA-1.
    const char *sigBase64 = rsa.signStringENC("text to sign","SHA-256");
    if (rsa.get_LastMethodSuccess() != true) {
        strOut.append(rsa.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Base64 signature: ");
    strOut.append(sigBase64);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }