(MFC) PKCS7 Encrypt using Multiple Certificates

Encrypts MIME using multiple digital certificates. Calls AddEncryptCert once per certificate, followed by a call to EncryptN. The MIME may be decrypted by any owner of one of the certificates + its associated private key.

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

See Also: Using MFC CString in Chilkat

#include <CkMime.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.

    CkMime mime;

    // Build a simple MIME message to be encrypted:
    bool success = mime.AddHeaderField("Content-Type","text/plain");
    success = mime.AddHeaderField("abc","123");
    mime.SetBody("This is a test");

    // A digital certificate is required to create PKCS7 encrypted MIME.
    // It can come from a variety of sources: .cer file, .pfx file, PEM files,
    // an in-memory representation, or directly from a Windows
    // registry-based certificate store.

    // Load one cert from a .cer file:
    CkCert cert1;
    success = cert1.LoadFromFile("myCert.cer");
    if (success == false) {
        strOut.append(cert1.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Load another cert ...
    CkCert cert2;
    success = cert2.LoadFromFile("anotherCert.cer");
    if (success == false) {
        strOut.append(cert2.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Tell the MIME object to use these certs for encrypting:
    // (AddEncryptCert shouldn't fail if we already know it contains
    // a valid certificate..)
    success = mime.AddEncryptCert(cert1);
    success = mime.AddEncryptCert(cert2);

    // Encrypt the MIME:
    success = mime.EncryptN();
    if (success == false) {
        strOut.append(mime.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Display the MIME:
    strOut.append(mime.getMime());
    strOut.append("\r\n");

    // The resulting S/MIME looks something like this:

    // abc: 123
    // Content-Disposition: attachment; filename="smime.p7m"
    // Content-Transfer-Encoding: base64
    // Content-Type: application/x-pkcs7-mime;
    //  name="smime.p7m"
    // 
    // MIID4QYJKoZIhvcNAQcDoIID0jCCA84CAQAxggNlMIIBgQIBADBpMFUxCzAJBgNVBAYTAlpBMSUw
    // IwYDVQQKExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMR8wHQYDVQQDExZUaGF3dGUgQ29k
    // ZSBTaWduaW5nIENBAhB4ouTcAmLszrGi170k1deSMA0GCSqGSIb3DQEBAQUABIIBAKnOPgmISrNH
    // Hd+zESvH5dl5TvBLCxLuIuH6cuZdowHzCqAUzaYFdn1rp88Vvu2x3s6WOvzje/+dE1x0YjEpeqxd
    // ufehlb6Jl9ucxSMWARWMxWGxu0eZGJVt+SBBrVddqdtrIU9lVt5rBxkU67P8PxgbwdNCX3qJENRO
    // P/rvp5ngoCkpIxeGqSkPvWv+CA3IXS8FPs8Sl4HNPiAj3e9RBm2MxI1u4cn1HvgGg8yHgHLMG5JF
    // LzGsmotSQaqEwq2JtOlkjfOwEI+ZhbWQupj6gen2aGc5sW3J26H1usxtV2TQ7WRRxqnZGmlh20dW
    // 4lo3kITYI+iapGlJXmrlDYh2CjkwggHcAgEAMIHDMIGuMQswCQYDVQQGEwJVUzELMAkGA1UECBMC
    // VVQxFzAVBgNVBAcTDlNhbHQgTGFrZSBDaXR5MR4wHAYDVQQKExVUaGUgVVNFUlRSVVNUIE5ldHdv
    // cmsxITAfBgNVBAsTGGh0dHA6Ly93d3cudXNlcnRydXN0LmNvbTE2MDQGA1UEAxMtVVROLVVTRVJG
    // aXJzdC1DbGllbnQgQXV0aGVudGljYXRpb24gYW5kIEVtYWlsAhAj50QEWUPwA+jXOiL8sMwXMA0G
    // CSqGSIb3DQEBAQUABIIBAFQ1cydWC4M9tdgAlCN03kP8eyuXajwT+5ByhOcJhjuCABg7U8w4Rx28
    // braGqV+TCBxjyMsqD0KcW49VT6ZHMpQ1yN8R72qDsidmfm9w3u0jVgsaaBkTJXMy4COY/3cZWmYG
    // dL3Qty8uFeQYddytt6UPJpGJZYsrdFG2doe6qHiRtAxxPrd0GmQRcGvxyDdsojkoBlTMbfwaXOI3
    // xepR/oh60x/3npUCsl2VpNPfo6oZoej6YZGEuz2MvuWvXVhvuqoTqXGwGDgYMxwTbPwklqZiJtsK
    // r5Ep3NlWAQX8MGWL0H+NC22cqJuqUCL05yqyAv+JMCpZGAwOVb/wiVNjpAIwYAYJKoZIhvcNAQcB
    // MBkGCCqGSIb3DQMCMA0CAToECA5NAJY12cU+gDgZFUc+nsQUUbiR1GH8iBVLI+XWlja9TXEe1Hzt
    // NlsOylRVBDzjNxUtX/zC0YR7bs+2Cf4JbyuMOA==


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }