(MFC) CoSign PKCS7/CMS Signed Data

See more Digital Signatures Examples

Demonstrates how to add a 2nd signature to a CMS SignedData. This is to add an additional signature, SignerInfo and certificate(s) to an existing CMS signed data.

In this example, we cosign an existing pdf.p7s

Note: The CoSign method is added in Chilkat v9.5.0.89.

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

See Also: Using MFC CString in Chilkat

#include <CkCrypt2.h>
#include <CkCert.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkCrypt2 crypt;
    CkCert cert;

    // Load a certificate in some way, such as from a smart card.
    // Chilkat provides other methods to load from a .pfx, .pem, or from the Windows certificate stores..
    bool success = cert.LoadFromSmartcard("");
    if (success == false) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // If we loaded from a smart card..
    // Use your smart card user PIN for signing.
    cert.put_SmartCardPin("0000");

    success = crypt.SetSigningCert(cert);
    if (success == false) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Load the file to be co-signed.
    // NOTE:  This is to cosign a PDF file contained within a CMS (PKCS7) message.
    // (In other words, the PDF is contained within the CMS SignedData, rather than the other way around
    // where a CMS signature is contained within a PDF.  Use Chilkat's PDF class to sign a PDF, which is
    // to embed a CMS signature within the PDF.)
    CkBinData bd;
    success = bd.LoadFile("qa_data/p7s/cosign/sample.pdf.p7s");
    if (success == false) {
        strOut.append("Failed to load pdf.p7s input file.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // bd2 will contain the co-signed result.
    CkBinData bd2;
    success = crypt.CoSign(bd,cert,bd2);
    if (success == false) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    success = bd.WriteFile("qa_output/cosigned.pdf.p7s");
    if (success == false) {
        strOut.append("Failed to save pdf.p7s output file.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }