Unicode C

Encrypt File in Chunks using AES CBC

See more Encryption Examples

Demonstrates how to use the FirstChunk/LastChunk properties to encrypt a file chunk-by-chunk. Unicode C

#include <C_CkCrypt2W.h>
#include <C_CkFileAccessW.h>
#include <C_CkBinDataW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkCrypt2W crypt;
    const wchar_t *fileToEncrypt;
    HCkFileAccessW facIn;
    const wchar_t *outputEncryptedFile;
    HCkFileAccessW facOutEnc;
    int chunkSize;
    int numChunks;
    HCkBinDataW bd;
    int i;
    const wchar_t *decryptedFile;
    BOOL bSame;

    success = FALSE;

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

    crypt = CkCrypt2W_Create();

    CkCrypt2W_putCryptAlgorithm(crypt,L"aes");
    CkCrypt2W_putCipherMode(crypt,L"cbc");
    CkCrypt2W_putKeyLength(crypt,256);

    CkCrypt2W_SetEncodedKey(crypt,L"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F",L"hex");
    CkCrypt2W_SetEncodedIV(crypt,L"000102030405060708090A0B0C0D0E0F",L"hex");

    fileToEncrypt = L"qa_data/hamlet.xml";
    facIn = CkFileAccessW_Create();
    success = CkFileAccessW_OpenForRead(facIn,fileToEncrypt);
    if (success != TRUE) {
        wprintf(L"Failed to open file that is to be encrytped.\n");
        CkCrypt2W_Dispose(crypt);
        CkFileAccessW_Dispose(facIn);
        return;
    }

    outputEncryptedFile = L"c:/temp/qa_output/hamlet.enc";
    facOutEnc = CkFileAccessW_Create();
    success = CkFileAccessW_OpenForWrite(facOutEnc,outputEncryptedFile);
    if (success != TRUE) {
        wprintf(L"Failed to encrypted output file.\n");
        CkCrypt2W_Dispose(crypt);
        CkFileAccessW_Dispose(facIn);
        CkFileAccessW_Dispose(facOutEnc);
        return;
    }

    // Let's encrypt in 10000 byte chunks.
    chunkSize = 10000;
    numChunks = CkFileAccessW_GetNumBlocks(facIn,chunkSize);

    CkCrypt2W_putFirstChunk(crypt,TRUE);
    CkCrypt2W_putLastChunk(crypt,FALSE);

    bd = CkBinDataW_Create();

    i = 0;
    while (i < numChunks) {
        i = i + 1;
        if (i == numChunks) {
            CkCrypt2W_putLastChunk(crypt,TRUE);
        }

        // Read the next chunk from the file.
        // The last chunk will be whatever amount remains in the file..
        CkBinDataW_Clear(bd);
        CkFileAccessW_FileReadBd(facIn,chunkSize,bd);

        // Encrypt.
        CkCrypt2W_EncryptBd(crypt,bd);

        // Write the encrypted chunk to the output file.
        CkFileAccessW_FileWriteBd(facOutEnc,bd,0,0);

        CkCrypt2W_putFirstChunk(crypt,FALSE);
    }

    // Make sure both FirstChunk and LastChunk are restored to TRUE after
    // encrypting or decrypting in chunks.  Otherwise subsequent encryptions/decryptions
    // will produce unexpected results.
    CkCrypt2W_putFirstChunk(crypt,TRUE);
    CkCrypt2W_putLastChunk(crypt,TRUE);

    CkFileAccessW_FileClose(facIn);
    CkFileAccessW_FileClose(facOutEnc);

    // Decrypt the encrypted output file in a single call using CBC mode:
    decryptedFile = L"qa_output/hamlet_dec.xml";
    success = CkCrypt2W_CkDecryptFile(crypt,outputEncryptedFile,decryptedFile);
    // Assume success for the example..

    // Compare the contents of the decrypted file with the original file:
    bSame = CkFileAccessW_FileContentsEqual(facIn,fileToEncrypt,decryptedFile);
    wprintf(L"bSame = %d\n",bSame);


    CkCrypt2W_Dispose(crypt);
    CkFileAccessW_Dispose(facIn);
    CkFileAccessW_Dispose(facOutEnc);
    CkBinDataW_Dispose(bd);

    }