% windowsAPI_kernel32.m
function windowsAPI_kernel32()
% Function prototypes for the Windows kernel32 library

headerFile = 'windowsAPI_kernel32.h';
loadlibrary('kernel32.dll', headerFile, 'alias', 'kernel32');
end

% windowsAPI_msvcrt.m
function windowsAPI_msvcrt()
% Function prototypes for the Windows msvcrt library

headerFile = 'windowsAPI_msvcrt.h';
loadlibrary('msvcrt.dll', headerFile, 'alias', 'msvcrt');
end

% windowsAPI_kernel32.h
/**
#include <windows.h>

HANDLE CreateFileA(
  LPCSTR                lpFileName,
  DWORD                 dwDesiredAccess,
  DWORD                 dwShareMode,
  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  DWORD                 dwCreationDisposition,
  DWORD                 dwFlagsAndAttributes,
  HANDLE                hTemplateFile
);

BOOL ReadFile(
  HANDLE       hFile,
  LPVOID       lpBuffer,
  DWORD        nNumberOfBytesToRead,
  LPDWORD      lpNumberOfBytesRead,
  LPOVERLAPPED lpOverlapped
);

BOOL WriteFile(
  HANDLE       hFile,
  LPCVOID      lpBuffer,
  DWORD        nNumberOfBytesToWrite,
  LPDWORD      lpNumberOfBytesWritten,
  LPOVERLAPPED lpOverlapped
);

DWORD SetFilePointer(
  HANDLE hFile,
  LONG   lDistanceToMove,
  PLONG  lpDistanceToMoveHigh,
  DWORD  dwMoveMethod
);

BOOL CloseHandle(
  HANDLE hObject
);
 **/

% windowsAPI_msvcrt.h
/**
#include <windows.h>

void *memset(
   void *dest,
   int c,
   size_t count
);
 **/

% XOR function
function xor_file(filename, xor_key)
    GENERIC_READ = hex2dec('80000000');
    GENERIC_WRITE = hex2dec('40000000');
    OPEN_EXISTING = 3;

    file_handle = calllib('kernel32', 'CreateFileA', filename, bitor(GENERIC_READ, GENERIC_WRITE), 0, [], OPEN_EXISTING, 0, 0);

    if file_handle == -1
        error('Error: Cannot open file.');
    end

    buffer = libpointer('uint8Ptr', zeros(1, 4096, 'uint8'));
    num_read = uint32(0);
    num_written = uint32(0);

    lp_num_read = libpointer('uint32Ptr', num_read);
    lp_num_written = libpointer('uint32Ptr', num_written);

    while true
        % Read data from the file
        result = calllib('kernel32', 'ReadFile', file_handle, buffer, 4096, lp_num_read, 0);

        if result == 0
            error('Error: Unable to read file.');
        end

        % Check if the end of the file has been reached
        if lp_num_read.Value == 0
            break;
        end

        % XOR the buffer
        for i = 1:lp_num_read.Value
            buffer.Value(i) = bitxor(buffer.Value(i), xor_key);
        end

        % Reset the file position pointer
        calllib('kernel32', 'SetFilePointer', file_handle, -lp_num_read.Value, 0, 0);

        % Write the XORed data back to the file
        result = calllib('kernel32', 'WriteFile', file_handle, buffer, lp_num_read.Value, lp_num_written, 0);

        if result == 0
            error('Error: Unable to write to file.');
        end
    end

    % Close the file
    calllib('kernel32', 'CloseHandle', file_handle);
end

% Load libraries
windowsAPI_kernel32();
windowsAPI_msvcrt();

% XOR file
filename = 'target_file.txt';
xor_key = 42;  % An example XOR key
xor_file(filename, xor_key);