Unicode C

AES Encrypt and Decrypt a File

_LANGUAGE_ demonstrates how to AES encrypt a file of any size, and then decrypt. Unicode C

#include <C_CkCrypt2W.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkCrypt2W crypt;
    const wchar_t *ivHex;
    const wchar_t *keyHex;
    const wchar_t *inFile;
    const wchar_t *outFile;
    HCkCrypt2W decrypt;

    success = FALSE;

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

    crypt = CkCrypt2W_Create();

    CkCrypt2W_putCryptAlgorithm(crypt,L"aes");

    //  CipherMode may be "ecb" or "cbc"
    CkCrypt2W_putCipherMode(crypt,L"cbc");

    //  KeyLength may be 128, 192, 256
    CkCrypt2W_putKeyLength(crypt,256);

    //  The padding scheme determines the contents of the bytes
    //  that are added to pad the result to a multiple of the
    //  encryption algorithm's block size.  AES has a block
    //  size of 16 bytes, so encrypted output is always
    //  a multiple of 16.
    CkCrypt2W_putPaddingScheme(crypt,0);

    //  An initialization vector is required if using CBC mode.
    //  ECB mode does not use an IV.
    //  The length of the IV is equal to the algorithm's block size.
    //  It is NOT equal to the length of the key.
    ivHex = L"000102030405060708090A0B0C0D0E0F";
    CkCrypt2W_SetEncodedIV(crypt,ivHex,L"hex");

    //  The secret key must equal the size of the key.  For
    //  256-bit encryption, the binary secret key is 32 bytes.
    //  For 128-bit encryption, the binary secret key is 16 bytes.
    keyHex = L"000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
    CkCrypt2W_SetEncodedKey(crypt,keyHex,L"hex");

    //  Encrypt a file, producing the .aes as output.
    //  The input file is unchanged, the output .aes contains the encrypted
    //  contents of the input file.

    //  Note: The .aes output file has no file format.  It is simply a stream
    //  of bytes that resembles random binary data.
    inFile = L"/Users/chilkat/testData/pdf/sample.pdf";
    outFile = L"/Users/chilkat/testData/p7m/sample.pdf.aes";
    success = CkCrypt2W_CkEncryptFile(crypt,inFile,outFile);
    if (success != TRUE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(crypt));
        CkCrypt2W_Dispose(crypt);
        return;
    }

    //  For demonstration purposes, a different instance of the object will be used
    //  for decryption.
    decrypt = CkCrypt2W_Create();

    //  All settings must match to be able to decrypt:
    CkCrypt2W_putCryptAlgorithm(decrypt,L"aes");
    CkCrypt2W_putCipherMode(decrypt,L"cbc");
    CkCrypt2W_putKeyLength(decrypt,256);
    CkCrypt2W_putPaddingScheme(decrypt,0);
    CkCrypt2W_SetEncodedIV(decrypt,ivHex,L"hex");
    CkCrypt2W_SetEncodedKey(decrypt,keyHex,L"hex");

    //  Decrypt the .aes
    inFile = L"/Users/chilkat/testData/p7m/sample.pdf.aes";
    outFile = L"/Users/chilkat/testData/pdf/recovered.pdf";
    success = CkCrypt2W_CkDecryptFile(decrypt,inFile,outFile);
    if (success == FALSE) {
        wprintf(L"%s\n",CkCrypt2W_lastErrorText(decrypt));
        CkCrypt2W_Dispose(crypt);
        CkCrypt2W_Dispose(decrypt);
        return;
    }

    wprintf(L"Success!\n");


    CkCrypt2W_Dispose(crypt);
    CkCrypt2W_Dispose(decrypt);

    }