(MFC) Encrypt/Decrypt using PFX to produce -----BEGIN PKCS7----- ... -----END PKCS7-----

First we encrypt using a certificate + public key to produce output such as:

-----BEGIN PKCS7-----
MIIHPwYJKoZIhvcNAQcEoIIHMDCCBywC ...
...
...
-----END PKCS7-----

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

See Also: Using MFC CString in Chilkat

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

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCrypt2 crypt;

    // Specify the encryption to be used.
    // "pki" indicates "Public Key Infrastructure" and will create a PKCS7 encrypted (enveloped) message.
    crypt.put_CryptAlgorithm("pki");
    crypt.put_Pkcs7CryptAlg("aes");
    crypt.put_KeyLength(128);
    crypt.put_OaepHash("sha256");
    crypt.put_OaepPadding(true);

    // A certificate is needed as the encryption key.
    // Althought the PFX contains the associated private key, we don't need it for encryption.
    // (A certificate usually contains the public key by default.)
    CkCert cert;
    bool success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123");
    if (success != true) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Tell the crypt object to use the certificate.
    crypt.SetEncryptCert(cert);

    const char *toBeEncrypted = "This string is to be encrypted.";

    // Get the result in multi-line BASE64 MIME format.
    crypt.put_EncodingMode("base64_mime");

    const char *encryptedStr = crypt.encryptStringENC(toBeEncrypted);
    if (success != true) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Make a "-----BEGIN PKCS7-----" ... "-----END PKCS7-----" sandwich...
    CkStringBuilder sb;
    sb.AppendLine("-----BEGIN PKCS7-----",true);
    sb.Append(encryptedStr);
    sb.AppendLine("-----END PKCS7-----",true);

    const char *outStr = sb.getAsString();

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

    // Sample output:

    // -----BEGIN PKCS7-----
    // MIICXAYJKoZIhvcNAQcDoIICTTCCAkkCAQAxggH0MIIB8AIBADCBrDCBlzELMAkGA1UEBhMCR0Ix
    // GzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMR
    // Q09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0
    // aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEB6M1ZwZdZU7LrAIdurulmUwOAYJKoZIhvcNAQEHMCug
    // DzANBglghkgBZQMEAgEFAKEYMBYGCSqGSIb3DQEBCDAJBgUrDgMCGgUABIIBAK/BZG/iXJ8az7zL
    // 8EQ77mc+oDPQ4w1hyytK2ip4djkPVvTfYhcoDQ+G/DBU+urJfrVBi5H9gmpXwYyfKlyUxBVRVEJl
    // V/V5QQi4JmNTFbmgWh5tp9zDS98l6A2Va4Zs0Wy/owGLfvwitlxd1dsfVAV2hmBYS24BMpNcty5/
    // 0atcKYmSou13G78ztTKdMy1tECgZy8kerMsPdDQbSxEZkT3KpQ8C5uEQqYF3bIVaeZzha/Ywieh/
    // tvO0T4aAmeJufwkNdVECmU7kuhnNaVPXknFl7jeibTl6zA/VcJKBKcIYT9FRC7KjdooI8q+jtQ/V
    // k6RP4POaowkFg1QWRPEWeqIwTAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBAgQQEEFQduqeJqXQXzy4
    // JpkoDoAgdldJDB9zEkpMpgr5/fR2iLvh5kC6BPfhOYjsawBY4Ok=
    // -----END PKCS7-----

    // ----------------------------------------------------------------------------------------
    // Let's Decrypt the above string.

    // Start with what was produced above..
    sb.Clear();
    bool bCrlf = true;
    sb.AppendLine("-----BEGIN PKCS7-----",bCrlf);
    sb.AppendLine("MIICXAYJKoZIhvcNAQcDoIICTTCCAkkCAQAxggH0MIIB8AIBADCBrDCBlzELMAkGA1UEBhMCR0Ix",bCrlf);
    sb.AppendLine("GzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMR",bCrlf);
    sb.AppendLine("Q09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0",bCrlf);
    sb.AppendLine("aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEB6M1ZwZdZU7LrAIdurulmUwOAYJKoZIhvcNAQEHMCug",bCrlf);
    sb.AppendLine("DzANBglghkgBZQMEAgEFAKEYMBYGCSqGSIb3DQEBCDAJBgUrDgMCGgUABIIBAK/BZG/iXJ8az7zL",bCrlf);
    sb.AppendLine("8EQ77mc+oDPQ4w1hyytK2ip4djkPVvTfYhcoDQ+G/DBU+urJfrVBi5H9gmpXwYyfKlyUxBVRVEJl",bCrlf);
    sb.AppendLine("V/V5QQi4JmNTFbmgWh5tp9zDS98l6A2Va4Zs0Wy/owGLfvwitlxd1dsfVAV2hmBYS24BMpNcty5/",bCrlf);
    sb.AppendLine("0atcKYmSou13G78ztTKdMy1tECgZy8kerMsPdDQbSxEZkT3KpQ8C5uEQqYF3bIVaeZzha/Ywieh/",bCrlf);
    sb.AppendLine("tvO0T4aAmeJufwkNdVECmU7kuhnNaVPXknFl7jeibTl6zA/VcJKBKcIYT9FRC7KjdooI8q+jtQ/V",bCrlf);
    sb.AppendLine("k6RP4POaowkFg1QWRPEWeqIwTAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBAgQQEEFQduqeJqXQXzy4",bCrlf);
    sb.AppendLine("JpkoDoAgdldJDB9zEkpMpgr5/fR2iLvh5kC6BPfhOYjsawBY4Ok=",bCrlf);
    sb.AppendLine("-----END PKCS7-----",bCrlf);

    CkCrypt2 decrypt;
    decrypt.put_CryptAlgorithm("pki");

    // Use the same cert + private key from the PFX above.
    // For decryption, we need the private key.  Given that the certificate was loaded from a PFX,
    // we should already have it.
    success = decrypt.SetDecryptCert(cert);

    decrypt.put_EncodingMode("base64");
    const char *decryptedText = decrypt.decryptStringENC(sb.getBetween("-----BEGIN PKCS7-----","-----END PKCS7-----"));

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


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }