RSA Encrypt and Decrypt Strings

MFC sample code to RSA public-key encrypt and decrypt strings using public and private keys.

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// Needs #include <CkRsa.h>

    CkString strOut;

    CkRsa rsa;

    bool success;
    success = rsa.UnlockComponent("Anything for 30-day trial");
    if (success != true) {
        strOut.append("RSA component unlock failed\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    //  This example also generates the public and private
    //  keys to be used in the RSA encryption.
    //  Normally, you would generate a key pair once,
    //  and distribute the public key to your partner.
    //  Anything encrypted with the public key can be
    //  decrypted with the private key.  The reverse is
    //  also true: anything encrypted using the private
    //  key can be decrypted using the public key.

    //  Generate a 1024-bit key.  Chilkat RSA supports
    //  key sizes ranging from 512 bits to 4096 bits.
    success = rsa.GenerateKey(1024);
    if (success != true) {
        strOut.append(rsa.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    //  Keys are exported in XML format:
    const char * publicKey;
    publicKey = rsa.exportPublicKey();
    const char * privateKey;
    privateKey = rsa.exportPrivateKey();

    const char * plainText;
    plainText = "Encrypting and decrypting should be easy!";

    //  Start with a new RSA object to demonstrate that all we
    //  need are the keys previously exported:
    CkRsa rsaEncryptor;

    //  Encrypted output is always binary.  In this case, we want
    //  to encode the encrypted bytes in a printable string.
    //  Our choices are "hex", "base64", "url", "quoted-printable".
    rsaEncryptor.put_EncodingMode("hex");

    //  We'll encrypt with the public key and decrypt with the private
    //  key.  It's also possible to do the reverse.
    rsaEncryptor.ImportPublicKey(publicKey);

    bool usePrivateKey;
    usePrivateKey = false;
    const char * encryptedStr;
    encryptedStr = rsaEncryptor.encryptStringENC(plainText,usePrivateKey);
    strOut.append(encryptedStr);
    strOut.append("\r\n");

    //  Now decrypt:
    CkRsa rsaDecryptor;

    rsaDecryptor.put_EncodingMode("hex");
    rsaDecryptor.ImportPrivateKey(privateKey);

    usePrivateKey = true;
    const char * decryptedStr;
    decryptedStr = rsaDecryptor.decryptStringENC(encryptedStr,usePrivateKey);

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

    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());