/* shift_constants.c - Don Yang (uguu.org)

   Find appropriate transformation constants to remap undesirable
   characters in string.

   2014-10-16
                                                                           */

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

int main()
{
   int mul1, mul2, shift, boundary, c, target, all_good;
   int translation[256];
   char text[] = "('A`)/*#:\nTimeHecateIIGlock18CjammedYOUWIN!Game over.";

   for(mul1 = 1; mul1 < 256; mul1++)
   {
      for(mul2 = 1; mul2 < 256; mul2++)
      {
         if( mul1 == mul2 )
            continue;
         for(shift = 0; shift < 256; shift++)
         {
            for(boundary = 33; boundary < 127; boundary++)
            {
               /* Build reverse map */
               memset(translation, 0, sizeof(translation));
               for(c = 33; c < 127; c++)
               {
                  if( c == '\"' || c == '\\' )
                     continue;
                  target = (c * (c < boundary ? mul1 : mul2) + shift) % 256;
                  translation[target] = c;
               }

               /* Check map validity */
               all_good = 1;
               for(c = 0; text[c] != '\0'; c++)
               {
                  if( translation[(int)(text[c])] == 0 )
                  {
                     all_good = 0;
                     break;
                  }
               }
               if( all_good != 0 )
               {
                  printf("(chr * (chr < %d ? %d : %d) + %d) & 0xff\n",
                         boundary, mul1, mul2, shift);
               }
            }
         }
      }
   }

   return 0;
}