(C) RSA Encrypt Randomly Generated AES Key

Demonstrates how to RSA encrypt a randomly generated AES key.

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

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#include <C_CkPrng.h>
#include <C_CkBinData.h>
#include <C_CkCert.h>
#include <C_CkPublicKey.h>
#include <C_CkRsa.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPrng prng;
    HCkBinData bdAesKey;
    HCkCert cert;
    HCkPublicKey pubKey;
    HCkRsa rsa;
    const char *encryptedAesKey;

    success = FALSE;

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

    // First generate a 256-bit AES key (32 bytes).
    prng = CkPrng_Create();
    bdAesKey = CkBinData_Create();
    success = CkPrng_GenRandomBd(prng,32,bdAesKey);

    // Use a public key from a certificate for RSA encryption.
    cert = CkCert_Create();

    success = CkCert_LoadFromFile(cert,"qa_data/pem/mf_public_rsa.pem");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkPrng_Dispose(prng);
        CkBinData_Dispose(bdAesKey);
        CkCert_Dispose(cert);
        return;
    }

    pubKey = CkPublicKey_Create();
    CkCert_GetPublicKey(cert,pubKey);

    rsa = CkRsa_Create();
    success = CkRsa_UsePublicKey(rsa,pubKey);
    if (success == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkPrng_Dispose(prng);
        CkBinData_Dispose(bdAesKey);
        CkCert_Dispose(cert);
        CkPublicKey_Dispose(pubKey);
        CkRsa_Dispose(rsa);
        return;
    }

    // RSA encrypt our 32-byte AES key.
    // The contents of bdAesKey are replaced with result of the RSA encryption.
    success = CkRsa_EncryptBd(rsa,bdAesKey,FALSE);
    if (success == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkPrng_Dispose(prng);
        CkBinData_Dispose(bdAesKey);
        CkCert_Dispose(cert);
        CkPublicKey_Dispose(pubKey);
        CkRsa_Dispose(rsa);
        return;
    }

    // Return the result as a base64 string
    encryptedAesKey = CkBinData_getEncoded(bdAesKey,"base64");

    printf("encrypted AES key = %s\n",encryptedAesKey);


    CkPrng_Dispose(prng);
    CkBinData_Dispose(bdAesKey);
    CkCert_Dispose(cert);
    CkPublicKey_Dispose(pubKey);
    CkRsa_Dispose(rsa);

    }