(MFC) Streaming Compression --> Streaming Encryption

Demonstrate how to feed a compression stream into an encryption stream. This example does the following:

Data File --> Compress --> Encrypt --> Application Reads

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkCompression.h>
#include <CkCrypt2.h>
#include <CkStream.h>
#include <CkTask.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    bool success;

    //  Initialize the compression object.
    CkCompression compress;
    compress.put_Algorithm("deflate");

    //  Initialize the encryption object.
    CkCrypt2 crypt;
    crypt.put_CryptAlgorithm("chacha20");
    crypt.put_KeyLength(256);
    crypt.put_EncodingMode("hex");
    const char *ivHex = "000000000000000000000002";
    crypt.SetEncodedIV(ivHex,"hex");
    crypt.put_InitialCount(42);
    const char *keyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0";
    crypt.SetEncodedKey(keyHex,"hex");

    //  Setup the streams.
    //  streamC is for compression
    CkStream streamC;
    //  streamE is for encryption
    CkStream streamE;

    //  The source for the compressor is a file.
    streamC.put_SourceFile("qa_data/hamlet.xml");
    //  The source for the encryptor is the output of the compressor stream.
    success = streamE.SetSourceStream(streamC);

    //  Our application will be reading the output of streamE.
    //  Start the compression and encryption streams in background threads..
    CkTask *taskC = compress.CompressStreamAsync(streamC);
    CkTask *taskE = crypt.EncryptStreamAsync(streamE);
    success = taskC->Run();
    success = taskE->Run();

    //  Read the compressed and encrypted bytes.
    CkBinData outData;
    while ((streamE.get_EndOfStream() != true)) {
        if (streamE.get_DataAvailable() == true) {
            success = streamE.ReadBd(outData);
        }

    }

    //  Let's make sure the background task finished.
    //  It should already be the case that the task is finished.
    while (((taskE->get_Finished() != true) || (taskC->get_Finished() != true))) {
        taskE->SleepMs(20);
    }

    //  Get any remaining data that needs to be flushed.
    if (streamE.get_DataAvailable() == true) {
        success = streamE.ReadBd(outData);
    }

    //  Double-check for success..
    if (taskE->get_TaskSuccess() != true) {
        strOut.append("async encryption failed:");
        strOut.append("\r\n");
        strOut.append(taskE->resultErrorText());
        strOut.append("\r\n");
        success = false;
    }

    //  Double-check for success..
    if (taskC->get_TaskSuccess() != true) {
        strOut.append("async compression failed:");
        strOut.append("\r\n");
        strOut.append(taskC->resultErrorText());
        strOut.append("\r\n");
        success = false;
    }

    delete taskE;
    delete taskC;

    //  Save the compressed/encrypted data to a file.
    outData.WriteFile("qa_output/compressedEncrypted.dat");

    strOut.append("The async compress/encrypt was successful.");
    strOut.append("\r\n");

    //  Let's decrypt and decompress to further verify...
    success = crypt.DecryptBd(outData);
    success = compress.DecompressBd(outData);

    //  outData should contain the original data..
    success = outData.WriteFile("qa_output/original_hamlet.xml");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }