(MFC) Sign a Byte Array to Create a Detached Signature in a Byte Array

Signs data contained in a byte array to produce a detached signature (also in a byte array). Also shows how to verify the signature.

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

See Also: Using MFC CString in Chilkat

#include <CkCert.h>
#include <CkFileAccess.h>
#include <CkByteData.h>
#include <CkCrypt2.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCert cert;
    bool success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123");
    if (success == false) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkFileAccess fac;

    CkByteData fileBytes;
    success = fac.ReadEntireFile("qa_data/pdf/sample.pdf",fileBytes);
    if (fac.get_LastMethodSuccess() != true) {
        strOut.append(fac.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkCrypt2 crypt;

    success = crypt.SetSigningCert(cert);

    // We can sign any type of file.
    // The result is a detached signature (a signature that does not contain the data being signed).

    CkByteData sigBytes;
    success = crypt.SignBytes(fileBytes,sigBytes);
    if (crypt.get_LastMethodSuccess() != true) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    success = fac.WriteEntireFile("qa_output/sample.pdf.p7s",sigBytes);
    if (fac.get_LastMethodSuccess() != true) {
        strOut.append(fac.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // We can verify the detached signature like this
    bool verified = crypt.VerifyBytes(fileBytes,sigBytes);
    if (crypt.get_LastMethodSuccess() != true) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Verified = ");
    strOut.appendInt(verified);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }