(C++) RSA Encrypt and Decrypt Strings

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

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#include <CkRsa.h>
#include <CkPrivateKey.h>
#include <CkPublicKey.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.

    CkRsa rsa;

    // 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 2048-bit key.  Chilkat RSA supports
    // key sizes ranging from 512 bits to 4096 bits.
    CkPrivateKey privKey;
    success = rsa.GenKey(2048,privKey);
    if (success == false) {
        std::cout << rsa.lastErrorText() << "\r\n";
        return;
    }

    CkPublicKey pubKey;
    privKey.ToPublicKey(pubKey);

    const char *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.
    success = rsaEncryptor.UsePublicKey(pubKey);

    bool usePrivateKey = false;
    const char *encryptedStr = rsaEncryptor.encryptStringENC(plainText,usePrivateKey);
    std::cout << encryptedStr << "\r\n";

    // Now decrypt:
    CkRsa rsaDecryptor;

    rsaDecryptor.put_EncodingMode("hex");
    success = rsaDecryptor.UsePrivateKey(privKey);

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

    std::cout << decryptedStr << "\r\n";
    }