(Unicode C++) RSA Encrypt and Decrypt Credit Card Numbers

Unicode C++ sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.)

Note: This example requires Chilkat v11.0.0 or greater.

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#include <CkRsaW.h>
#include <CkPrivateKeyW.h>
#include <CkPublicKeyW.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkRsaW rsa;

    CkPrivateKeyW privKey;

    // Load an RSA private key from a file:
    success = privKey.LoadAnyFormatFile(L"rsaPrivateKey.key",L"");
    if (success == false) {
        wprintf(L"%s\n",privKey.lastErrorText());
        return;
    }

    // Get the public part of the private key.
    CkPublicKeyW pubKey;
    privKey.ToPublicKey(pubKey);

    success = rsa.UsePublicKey(pubKey);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // Encrypt a VISA credit card number:
    // 1234-5678-0000-9999
    const wchar_t *ccNumber = L"1234567800009999";

    bool usePrivateKey = false;
    rsa.put_EncodingMode(L"base64");
    const wchar_t *encryptedStr = rsa.encryptStringENC(ccNumber,usePrivateKey);
    wprintf(L"Encrypted:\n");
    wprintf(L"%s\n",encryptedStr);

    // Now decrypt:
    CkRsaW rsaDecryptor;

    rsaDecryptor.put_EncodingMode(L"base64");
    rsaDecryptor.UsePrivateKey(privKey);

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

    wprintf(L"Decrypted:\n");
    wprintf(L"%s\n",decryptedStr);

    // Important: RSA encryption should only be used to encrypt small amounts of data.
    // It is typically used for encrypting symmetric encryption
    // keys such that a symmetric encryption algorithm, such as 
    // AES is then used to encrypt/decrypt bulk data
    }