ipfFile = File.open(pathToNewIpfFile, 'w');
origFile = File.open(pathToOrigFile, 'r');
moddedFile = File.open(pathToModdedFile, 'r');

byte diffByte = 0;
foreach (int i = 0; i < size(origFile); i++)
{
    if(i < size(moddedFile))
    {
        diffByte = origFile[i] ^ moddedFile[i];
    }
    else
    {
        break;
    }
    ipfFile.write(diffByte);
}