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.

C++

#include <CkCompression.h>
#include <CkJsonObject.h>
#include <CkCrypt2.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.

    CkCompression compress;
    compress.put_Algorithm("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.
    CkJsonObject json;
    json.UpdateString("cryptAlgorithm","aes");
    json.UpdateString("cipherMode","cbc");
    json.UpdateInt("keyLength",128);
    json.UpdateInt("paddingScheme",0);
    json.UpdateString("encodedIV","000102030405060708090A0B0C0D0E0F");
    json.UpdateString("encodedKey","000102030405060708090A0B0C0D0E0F");

    // Do file-to-file compression+encryption in a single call.
    const char *inPath = "qa_data/largeFile.dat";
    const char *outPath = "c:/temp/qa_output/compressed_encrypted.dat";
    success = compress.CompressEncryptFile(json,inPath,outPath);
    if (success == false) {
        std::cout << compress.lastErrorText() << "\r\n";
        return;
    }

    // We can do file-to-file decrypt/decompress like this:
    const char *inPath2 = outPath;
    const char *outPath2 = "c:/temp/qa_output/restored.dat";
    success = compress.DecryptDecompressFile(json,inPath2,outPath2);
    if (success == false) {
        std::cout << compress.lastErrorText() << "\r\n";
        return;
    }

    // Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    CkCrypt2 crypt;
    crypt.put_CryptAlgorithm("aes");
    crypt.put_CipherMode("cbc");
    crypt.put_KeyLength(128);
    crypt.put_PaddingScheme(0);
    crypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex");
    crypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex");

    const char *decryptedPath = "c:/temp/qa_output/decrypted.dat";
    success = crypt.CkDecryptFile(inPath2,decryptedPath);
    if (success == false) {
        std::cout << crypt.lastErrorText() << "\r\n";
        return;
    }

    const char *outPath3 = "c:/temp/qa_output/restored_in_two_steps.dat";
    success = compress.DecompressFile(decryptedPath,outPath3);
    if (success == false) {
        std::cout << compress.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Success." << "\r\n";
    }