(MFC) RSAES-OAEP Encrypt String with AES-128 Content Encryption and SHA256

Encrypts a string using RSAES-OAEP with SHA256 and AES-128 content encryption to produce PKCS7 output (base64 encoded).

Note: This example requires Chilkat v9.5.0.67 or greater.

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

See Also: Using MFC CString in Chilkat

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

    // First build a string to be encrypted
    CkStringBuilder sb;
    int i = 1;
    while (i < 25) {
        sb.AppendInt(i);
        sb.Append(" the quick brown fox jumped over the lazy dog.\r\n");
        i = i + 1;
    }

    strOut.append(sb.getAsString());
    strOut.append("\r\n");

    // The string to be encrypted looks like this:

    // 1 the quick brown fox jumped over the lazy dog.
    // 2 the quick brown fox jumped over the lazy dog.
    // 3 the quick brown fox jumped over the lazy dog.
    // 4 the quick brown fox jumped over the lazy dog.
    // 5 the quick brown fox jumped over the lazy dog.
    // 6 the quick brown fox jumped over the lazy dog.
    // ...

    // Load a digital certificate. 
    // We don't need the private key for encryption.
    // Only the public key is needed (which is included in a certificate).
    CkCert cert;
    bool success = cert.LoadFromFile("qa_data/rsaes-oaep/cert.pem");
    if (success != true) {
        strOut.append(cert.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkCrypt2 crypt;

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

    // Indicate that we want PKI encryption (i.e. public-key infrastructure)
    // to produce a CMS message (Cryptographic Message Syntax/PKCS7),
    // that is be created with RSAES-OAEP padding, SHA256, and AES-128 for the
    // bulk encryption.
    crypt.put_CryptAlgorithm("pki");
    crypt.put_Pkcs7CryptAlg("aes");
    crypt.put_KeyLength(128);
    crypt.put_OaepHash("sha256");
    crypt.put_OaepPadding(true);

    // Also, don't forget to be specific about the character encoding (byte representation) of the
    // string to be encrypted.
    crypt.put_Charset("utf-8");

    // Now indicate that the PKCS7 output is to be returned in the base64 encoding.
    crypt.put_EncodingMode("base64");

    const char *base64Pkcs7 = crypt.encryptStringENC(sb.getAsString());
    if (crypt.get_LastMethodSuccess() != true) {
        strOut.append(crypt.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Show the output
    strOut.append(base64Pkcs7);
    strOut.append("\r\n");

    // This base64 can be copy-and-pasted into the form at http://lapo.it/asn1js/
    // to verify that all the chosen algorithms were indeed used.

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


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }