Unicode C++ Requires Chilkat v11.0.0+

RSA Encrypt String to Encoded Result and Reverse

See more RSA Examples

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

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

void ChilkatSample(void)
    {
    bool success = false;

    //  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.
    CkPublicKeyW pubKey;
    //  In all Chilkat methods expecting a path, you pass either absolute or relative paths.
    success = pubKey.LoadFromFile(L"rsaKeys/myTestRsaPublic.pem");
    if (success == false) {
        wprintf(L"%s\n",pubKey.lastErrorText());
        return;
    }

    CkRsaW rsa;

    //  Tell RSA to use the public key.
    rsa.UsePublicKey(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.
    rsa.put_Charset(L"utf-8");
    rsa.put_EncodingMode(L"base64");

    //  Be Careful when Using non-us-ascii String Literals in Source Code
    const wchar_t *encryptedB64 = rsa.encryptStringENC(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.
    CkPrivateKeyW privKey;
    const wchar_t *password = L"secret";
    success = privKey.LoadAnyFormatFile(L"rsaKeys/myTestRsaPrivate.pem",password);
    if (success == false) {
        wprintf(L"%s\n",privKey.lastErrorText());
        return;
    }

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

    //  Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
    rsa.put_Charset(L"utf-8");
    rsa.put_EncodingMode(L"base64");
    const wchar_t *originalText = rsa.decryptStringENC(encryptedB64,true);
    if (success == false) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

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