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 <C_CkCompression.h>
#include <C_CkJsonObject.h>
#include <C_CkCrypt2.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkCompression compress;
    HCkJsonObject json;
    const char *inPath;
    const char *outPath;
    const char *inPath2;
    const char *outPath2;
    HCkCrypt2 crypt;
    const char *decryptedPath;
    const char *outPath3;

    success = FALSE;

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

    compress = CkCompression_Create();
    CkCompression_putAlgorithm(compress,"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 = CkJsonObject_Create();
    CkJsonObject_UpdateString(json,"cryptAlgorithm","aes");
    CkJsonObject_UpdateString(json,"cipherMode","cbc");
    CkJsonObject_UpdateInt(json,"keyLength",128);
    CkJsonObject_UpdateInt(json,"paddingScheme",0);
    CkJsonObject_UpdateString(json,"encodedIV","000102030405060708090A0B0C0D0E0F");
    CkJsonObject_UpdateString(json,"encodedKey","000102030405060708090A0B0C0D0E0F");

    // Do file-to-file compression+encryption in a single call.
    inPath = "qa_data/largeFile.dat";
    outPath = "c:/temp/qa_output/compressed_encrypted.dat";
    success = CkCompression_CompressEncryptFile(compress,json,inPath,outPath);
    if (success == FALSE) {
        printf("%s\n",CkCompression_lastErrorText(compress));
        CkCompression_Dispose(compress);
        CkJsonObject_Dispose(json);
        return;
    }

    // We can do file-to-file decrypt/decompress like this:
    inPath2 = outPath;
    outPath2 = "c:/temp/qa_output/restored.dat";
    success = CkCompression_DecryptDecompressFile(compress,json,inPath2,outPath2);
    if (success == FALSE) {
        printf("%s\n",CkCompression_lastErrorText(compress));
        CkCompression_Dispose(compress);
        CkJsonObject_Dispose(json);
        return;
    }

    // Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    crypt = CkCrypt2_Create();
    CkCrypt2_putCryptAlgorithm(crypt,"aes");
    CkCrypt2_putCipherMode(crypt,"cbc");
    CkCrypt2_putKeyLength(crypt,128);
    CkCrypt2_putPaddingScheme(crypt,0);
    CkCrypt2_SetEncodedIV(crypt,"000102030405060708090A0B0C0D0E0F","hex");
    CkCrypt2_SetEncodedKey(crypt,"000102030405060708090A0B0C0D0E0F","hex");

    decryptedPath = "c:/temp/qa_output/decrypted.dat";
    success = CkCrypt2_CkDecryptFile(crypt,inPath2,decryptedPath);
    if (success == FALSE) {
        printf("%s\n",CkCrypt2_lastErrorText(crypt));
        CkCompression_Dispose(compress);
        CkJsonObject_Dispose(json);
        CkCrypt2_Dispose(crypt);
        return;
    }

    outPath3 = "c:/temp/qa_output/restored_in_two_steps.dat";
    success = CkCompression_DecompressFile(compress,decryptedPath,outPath3);
    if (success == FALSE) {
        printf("%s\n",CkCompression_lastErrorText(compress));
        CkCompression_Dispose(compress);
        CkJsonObject_Dispose(json);
        CkCrypt2_Dispose(crypt);
        return;
    }

    printf("Success.\n");


    CkCompression_Dispose(compress);
    CkJsonObject_Dispose(json);
    CkCrypt2_Dispose(crypt);

    }