// main.cpp - Encrypting a file.

#include  <iostream>
#include  <fstream>
#include  "Encrypt.h"
using namespace std;

const int  BUFSIZE = 2000;
char  buffer[BUFSIZE];
unsigned int   count;                   // character count
unsigned char  encryptCode;

int main( int argcount, char* args[ ] ) {
  
  // Read input and output files from the command line.
  if ( argcount < 3 ) {
    cout << "Usage: Encrypt infile outfile" << endl;
    return( -1 );
  }
  cout << "Encryption code [0-255]? ";
  cin  >> encryptCode;

  ifstream  infile(  args[1], ios::binary );
  ofstream  outfile( args[2], ios::binary );
  cout << "Reading " << args[1] << " and creating " << args[2] << endl;

  while ( !infile.eof( ) ) {
    infile.read( buffer, BUFSIZE );
    count = infile.gcount( );    outfile.write( buffer, count );
  }
  return( 0 );
}

// Encript.h

extern "C" {
  void  Encrypt( char* buf, long count, char eChar );
}

TITLE Encrypt Procedure      (Encrypt.asm)

.586
.model  flat, C

Encrypt PROTO,.code
Encrypt PROC,     mov  esi, buf
     mov  ecx, count
     mov  al,  eChar

 L1: xor  [esi], al
     inc  esi
     loop L1

     ret
Encrypt ENDP
END