Unicode C

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

See more Compression Examples

Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 or greater.

Unicode C

#include <C_CkCompressionW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkCrypt2W.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkCompressionW compress;
    HCkJsonObjectW json;
    const wchar_t *inPath;
    const wchar_t *outPath;
    const wchar_t *inPath2;
    const wchar_t *outPath2;
    HCkCrypt2W crypt;
    const wchar_t *decryptedPath;
    const wchar_t *outPath3;

    success = FALSE;

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

    compress = CkCompressionW_Create();
    CkCompressionW_putAlgorithm(compress,L"deflate");

    // Set encryption params.
    // The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
    // The encoded IV and Key must be specified as hex.
    json = CkJsonObjectW_Create();
    CkJsonObjectW_UpdateString(json,L"cryptAlgorithm",L"aes");
    CkJsonObjectW_UpdateString(json,L"cipherMode",L"cbc");
    CkJsonObjectW_UpdateInt(json,L"keyLength",128);
    CkJsonObjectW_UpdateInt(json,L"paddingScheme",0);
    CkJsonObjectW_UpdateString(json,L"encodedIV",L"000102030405060708090A0B0C0D0E0F");
    CkJsonObjectW_UpdateString(json,L"encodedKey",L"000102030405060708090A0B0C0D0E0F");

    // Do file-to-file compression+encryption in a single call.
    inPath = L"qa_data/largeFile.dat";
    outPath = L"c:/temp/qa_output/compressed_encrypted.dat";
    success = CkCompressionW_CompressEncryptFile(compress,json,inPath,outPath);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCompressionW_lastErrorText(compress));
        CkCompressionW_Dispose(compress);
        CkJsonObjectW_Dispose(json);
        return;
    }

    // We can do file-to-file decrypt/decompress like this:
    inPath2 = outPath;
    outPath2 = L"c:/temp/qa_output/restored.dat";
    success = CkCompressionW_DecryptDecompressFile(compress,json,inPath2,outPath2);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCompressionW_lastErrorText(compress));
        CkCompressionW_Dispose(compress);
        CkJsonObjectW_Dispose(json);
        return;
    }

    // Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    crypt = CkCrypt2W_Create();
    CkCrypt2W_putCryptAlgorithm(crypt,L"aes");
    CkCrypt2W_putCipherMode(crypt,L"cbc");
    CkCrypt2W_putKeyLength(crypt,128);
    CkCrypt2W_putPaddingScheme(crypt,0);
    CkCrypt2W_SetEncodedIV(crypt,L"000102030405060708090A0B0C0D0E0F",L"hex");
    CkCrypt2W_SetEncodedKey(crypt,L"000102030405060708090A0B0C0D0E0F",L"hex");

    decryptedPath = L"c:/temp/qa_output/decrypted.dat";
    success = CkCrypt2W_CkDecryptFile(crypt,inPath2,decryptedPath);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(crypt));
        CkCompressionW_Dispose(compress);
        CkJsonObjectW_Dispose(json);
        CkCrypt2W_Dispose(crypt);
        return;
    }

    outPath3 = L"c:/temp/qa_output/restored_in_two_steps.dat";
    success = CkCompressionW_DecompressFile(compress,decryptedPath,outPath3);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCompressionW_lastErrorText(compress));
        CkCompressionW_Dispose(compress);
        CkJsonObjectW_Dispose(json);
        CkCrypt2W_Dispose(crypt);
        return;
    }

    wprintf(L"Success.\n");


    CkCompressionW_Dispose(compress);
    CkJsonObjectW_Dispose(json);
    CkCrypt2W_Dispose(crypt);

    }