(Unicode C) Streaming Encryption

Encrypt and decrypt using a stream.

Chilkat C/C++ Library Downloads
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#include <C_CkCrypt2W.h>
#include <C_CkStreamW.h>
#include <C_CkStringArrayW.h>
#include <C_CkTaskW.h>

void ChilkatSample(void)
    {
    HCkCrypt2W crypt;
    const wchar_t *ivHex;
    const wchar_t *keyHex;
    const wchar_t *plainText;
    HCkStreamW stream;
    HCkStringArrayW eStrings;
    HCkTaskW task;
    BOOL success;
    const wchar_t *cipherText;
    int i;
    int n;

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

    crypt = CkCrypt2W_Create();

    // Setup encryption using the chacha20 algorithm...
    CkCrypt2W_putCryptAlgorithm(crypt,L"chacha20");
    CkCrypt2W_putKeyLength(crypt,256);
    CkCrypt2W_putEncodingMode(crypt,L"hex");
    ivHex = L"000000000000000000000002";
    CkCrypt2W_SetEncodedIV(crypt,ivHex,L"hex");
    CkCrypt2W_putInitialCount(crypt,42);
    keyHex = L"1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0";
    CkCrypt2W_SetEncodedKey(crypt,keyHex,L"hex");

    plainText = L"The quick brown fox jumped over the lazy dog.\r\n";

    stream = CkStreamW_Create();

    // We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
    eStrings = CkStringArrayW_Create();

    // Start a background task that will encrypt a stream.
    task = CkCrypt2W_EncryptStreamAsync(crypt,stream);
    success = CkTaskW_Run(task);

    // Write plainText to the stream, and read chacha20 encrypted text..

    for (i = 1; i <= 10; i++) {
        // Note: An encryption algorithm's block size will cause buffering,
        // and therefore not every loop iteration will produce output.
        success = CkStreamW_WriteString(stream,plainText);
        if (CkStreamW_getDataAvailable(stream) == TRUE) {
            cipherText = CkStreamW_readBytesENC(stream,L"hex");
            wprintf(L"%s\n",cipherText);
            success = CkStringArrayW_Append(eStrings,cipherText);
        }

    }

    // Tell the background task that the stream has ended.
    success = CkStreamW_WriteClose(stream);

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while ((CkTaskW_getFinished(task) != TRUE)) {
        CkTaskW_SleepMs(task,20);
    }

    // Get any remaining data available from the stream.
    if (CkStreamW_getDataAvailable(stream) == TRUE) {
        cipherText = CkStreamW_readBytesENC(stream,L"hex");
        wprintf(L"%s\n",cipherText);
        success = CkStringArrayW_Append(eStrings,cipherText);
    }

    if (CkTaskW_getTaskSuccess(task) != TRUE) {
        wprintf(L"async encryption failed:\n");
        wprintf(L"%s\n",CkTaskW_resultErrorText(task));
        success = FALSE;
    }

    CkTaskW_Dispose(task);

    wprintf(L"-- encrypt finished --\n");

    // Now decrypt to return the original.

    // Reset the stream object so it can be used again.
    CkStreamW_Reset(stream);

    // Start a background task that will decrypt a stream.
    task = CkCrypt2W_DecryptStreamAsync(crypt,stream);
    success = CkTaskW_Run(task);

    n = CkStringArrayW_getCount(eStrings);
    for (i = 0; i <= n - 1; i++) {
        success = CkStreamW_WriteBytesENC(stream,CkStringArrayW_getString(eStrings,i),L"hex");
        if (CkStreamW_getDataAvailable(stream) == TRUE) {
            plainText = CkStreamW_readString(stream);
            wprintf(L"%s\n",plainText);
        }

    }

    // Tell the background task that the stream has ended.
    success = CkStreamW_WriteClose(stream);

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while ((CkTaskW_getFinished(task) != TRUE)) {
        CkTaskW_SleepMs(task,20);
    }

    // Get any remaining data available from the stream.
    if (CkStreamW_getDataAvailable(stream) == TRUE) {
        plainText = CkStreamW_readString(stream);
        wprintf(L"%s\n",plainText);
    }

    if (CkTaskW_getTaskSuccess(task) != TRUE) {
        wprintf(L"async decryption failed:\n");
        wprintf(L"%s\n",CkTaskW_resultErrorText(task));
        success = FALSE;
    }

    CkTaskW_Dispose(task);

    wprintf(L"-- decrypt finished --\n");


    CkCrypt2W_Dispose(crypt);
    CkStreamW_Dispose(stream);
    CkStringArrayW_Dispose(eStrings);

    }