#include <stdio.h>
#include <string.h>
#include <windows.h>

/* All function indices in QuickCrypt.dll can be found in:*/
/* QuickCrypt Library Help (QuickCrypt Library Run-Time Dynamic Linking page) */
#define DES_INIT_INDEX          1
#define CBC_INIT_INDEX          71
#define CBC_PROCESS_INDEX       74

/* These constants can be found in QuickCrypt.h */
#define DES_BLOCKSIZE           8 
#define DES_CONTEXTSIZE         168 
#define DES_DEFAULTKEYSIZE      8 

#define ENCRYPT                 0
#define DECRYPT                 1

/* Declare pointer types for each function you need to use */
typedef void         ( _stdcall *PDESINIT )( void*, int, const void*, unsigned int );
typedef int          ( _stdcall *PCBCINIT )( void*, int, const void*, int );
typedef unsigned int ( _stdcall *PCBCPROCESS )( void*, void*, const void*, unsigned int );

/* performs DES encryption/decryption of memory buffer in CBC mode */
int EncryptDecryptBuffer( unsigned char* buff, const unsigned int buffsize, int dir, const unsigned char* iv, const unsigned char* key )
{
    /* dir: ENCRYPT - perform encryption */
    /*      DECRYPT - perform decryption */

    PDESINIT      pDESInit;
    PCBCINIT      pCBCInit;
    PCBCPROCESS   pCBCProcess;

    unsigned char context[DES_CONTEXTSIZE];
    int           padded = 1; /* true */

    /*****Load QuickCrypt.dll*************/
    HMODULE hModule = LoadLibrary( "QuickCrypt.dll" );
    if( !hModule )
    {
        printf( "Could not load QuickCrypt.dll library" );
        return 1;
    }

    /*****Get all function addresses*****/
    pDESInit      = (PDESINIT)GetProcAddress( hModule, (LPCSTR)DES_INIT_INDEX );
    pCBCInit      = (PCBCINIT)GetProcAddress( hModule, (LPCSTR)CBC_INIT_INDEX );
    pCBCProcess   = (PCBCPROCESS)GetProcAddress( hModule, (LPCSTR)CBC_PROCESS_INDEX );

    /***** Initialize context ****************/
    ( *pDESInit )( context, dir, key, DES_DEFAULTKEYSIZE );
    ( *pCBCInit )( context, dir, iv, padded );

    /***** Encrypt/Decrypt memory buffer *****/

    return ( *pCBCProcess )( context, buff, buff, buffsize ); /* in-place encryption/decryption */
}

void ShowBuffer( const unsigned char* buff, const unsigned int buffsize );

int main()
{
    /***** Define key, iv, memory buffer *****/

    char key[DES_DEFAULTKEYSIZE] = 
    {
        's', 'e', 'c', 'r', 'e', 't', 'l', 'y'
    };

    unsigned char iv[DES_BLOCKSIZE] = 
    {
        0x41, 0x3E, 0xF0, 0xA1, 0xC6, 0x11, 0xE5, 0x50
    };

    unsigned char buff[100] = 
    {
        0xA0, 0x76, 0xEE, 0x97, 0x8F, 0x12, 0x2C, 0x6F, 
        0xAA, 0x86, 0xC8, 0x13, 0x80, 0x80, 0xEA, 0xC4, 
        0x6B, 0xF0, 0x0D, 0x4A, 0x6A, 0xE7, 0x6E, 0x09, 
        0x12, 0x8B, 0xFE
    };

    unsigned int buffsize = 27;

    printf( "Initial memory buffer:\n" );
    ShowBuffer( buff, buffsize );

    /***** Encrypt memory buffer *************/
    
    buffsize = EncryptDecryptBuffer( buff, buffsize, ENCRYPT, iv, (const unsigned char*)key );

    printf( "Encrypted memory buffer:\n" );
    ShowBuffer( buff, buffsize );

    /***** Decrypt memory buffer *************/

    buffsize = EncryptDecryptBuffer( buff, buffsize, DECRYPT, iv, (const unsigned char*)key );

    printf( "Decrypted memory buffer:\n" );
    ShowBuffer( buff, buffsize );

    return 0;
}

void ShowBuffer( const unsigned char* buff, const unsigned int buffsize )
{
    unsigned int i = 0;

    for( ; i < buffsize; ++i )
    {
        printf( "%.2x ", (int)buff[ i ] );

        if( ( i + 1 ) % DES_BLOCKSIZE == 0 )
            printf( "\n" );
    }

    printf( "\n" );
}