//Usage: ISDGoBack.exe < new version setup.inx > old version setup.inx

#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#define XOR_VAL 0xF1

void main (void) 
{
    int i, c;
    int d, e;
    unsigned char b;
    // Set "stdin" and "stdout" to have binary mode
    setmode (_fileno (stdin), _O_BINARY);
    setmode (_fileno (stdout), _O_BINARY);
    // Rebuild the crypted INX
    for (i = 0; (c = getchar ()) != EOF; i++)
    {
        c ^= XOR_VAL;
        b = (unsigned char)((c >> 2) | (c << 6)) - (i % 71);
        putchar (b);
    }
}