(Unicode C) RSA Encrypt String to Encoded Result and Reverse

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Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse.

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#include <C_CkPublicKeyW.h>
#include <C_CkRsaW.h>
#include <C_CkPrivateKeyW.h>

void ChilkatSample(void)
    {
    HCkPublicKeyW pubKey;
    BOOL success;
    HCkRsaW rsa;
    const wchar_t *encryptedB64;
    HCkPrivateKeyW privKey;
    const wchar_t *password;
    const wchar_t *originalText;

    // The RSA public key is used for encryption, and the private key for decryption.

    // The public key's role is to make encryption accessible to anyone while ensuring that
    // only the private key holder can decrypt the messages.
    // The public key is designed to be widely distributed so anyone can use it to encrypt messages
    // intended for the owner of the private key.

    // Load our 2048-bit RSA public key.
    pubKey = CkPublicKeyW_Create();
    // In all Chilkat methods expecting a path, you pass either absolute or relative paths.
    success = CkPublicKeyW_LoadFromFile(pubKey,L"rsaKeys/myTestRsaPublic.pem");
    if (success == FALSE) {
        wprintf(L"%s\n",CkPublicKeyW_lastErrorText(pubKey));
        CkPublicKeyW_Dispose(pubKey);
        return;
    }

    rsa = CkRsaW_Create();

    // Tell RSA to use the public key.
    CkRsaW_ImportPublicKeyObj(rsa,pubKey);

    // RSA encryption is for small amounts of data, on the order of 200 bytes or less.
    // The maximum number of bytes that can be RSA encrypted depends
    // on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
    // For specific limits, see: RSA Encryption Maximum Number of Bytes

    // Encrypt the utf-8 byte representation of the string.
    CkRsaW_putCharset(rsa,L"utf-8");
    CkRsaW_putEncodingMode(rsa,L"base64");

    // Be Careful when Using non-us-ascii String Literals in Source Code
    encryptedB64 = CkRsaW_encryptStringENC(rsa,L"Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux",FALSE);

    // ------------------------------------------------------------------------------------------------------------------------
    // Let's decrypt, which requires the matching private key...

    // Load the matching 2048-bit RSA private key.
    privKey = CkPrivateKeyW_Create();
    password = L"secret";
    success = CkPrivateKeyW_LoadAnyFormatFile(privKey,L"rsaKeys/myTestRsaPrivate.pem",password);
    if (success == FALSE) {
        wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(privKey));
        CkPublicKeyW_Dispose(pubKey);
        CkRsaW_Dispose(rsa);
        CkPrivateKeyW_Dispose(privKey);
        return;
    }

    // Tell the RSA object to use the private key.
    CkRsaW_ImportPrivateKeyObj(rsa,privKey);

    // Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
    CkRsaW_putCharset(rsa,L"utf-8");
    CkRsaW_putEncodingMode(rsa,L"base64");
    originalText = CkRsaW_decryptStringENC(rsa,encryptedB64,TRUE);
    if (success == FALSE) {
        wprintf(L"%s\n",CkRsaW_lastErrorText(rsa));
        CkPublicKeyW_Dispose(pubKey);
        CkRsaW_Dispose(rsa);
        CkPrivateKeyW_Dispose(privKey);
        return;
    }

    wprintf(L"Original text = %s\n",originalText);
    wprintf(L"Success.\n");


    CkPublicKeyW_Dispose(pubKey);
    CkRsaW_Dispose(rsa);
    CkPrivateKeyW_Dispose(privKey);

    }