(MFC) Encrypt File using X.509 Certificate using AES in CBC Mode

Demonstrates how to encrypt a file using an X.509 Certificate's public key, where the underlying bulk encryption algorithm is 128-bit AES in CBC mode. (The underlying bulk encryption algorithm can be specified to be other algorithms/strengths.)

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

See Also: Using MFC CString in Chilkat

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

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCrypt2 crypt;

    //  Use public-key cryptography for encryption.
    crypt.put_CryptAlgorithm("pki");

    //  Get an X.509 certificate to use for encrypting.
    //  Note: Chilkat provides many different ways of loading a certificate, from many different formats,
    //  or if on Windows, from the installed certificates on the system.
    //  This example simply loads a certificate from a file.
    //  Also, for encryption, only the public key is needed.  Digital certificates embed the public key
    //  within the X.509 format itself.  Therefore, if you have a certificate, you also have the public key.
    CkCert cert;
    bool success = cert.LoadFromFile("qa_data/certs/testCert.cer");
    if (success != true) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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

    //  Indicate the underlying bulk encryption algorithm to be used:
    crypt.put_Pkcs7CryptAlg("aes");
    crypt.put_KeyLength(128);

    //  Note: When doing public-key encryption the underlying bulk symmetric cipher mode will always be CBC. (at least with Chilkat...)

    //  There's one last option that could be set.  If is the RSA encryption encryption/padding scheme.
    //  By default, RSAES_PKCS1-V1_5 is used.  If desired, the OaepPadding property could be set to true to
    //  use RSAES_OAEP.  (We'll leave it set at the default value of false)
    crypt.put_OaepPadding(false);

    //  Everything is specified.  Now just encrypt...
    //  The output is PKCS7 in binary DER format.
    success = crypt.CkEncryptFile("qa_data/hamlet.xml","qa_output/hamlet.p7");
    if (success != true) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }