#!/usr/bin/perl -w
# encode_text.pl - Don Yang (uguu.org)
#
# 07/04/07

use strict;

# Initialize data
my $text = join '', <DATA>;
$text =~ s/\s//g;
print "orig\n$text\n";

# Test xor keys
for(my $xor = 1; $xor < 127; $xor++)
{
   my @encoded_char = map { chr($_ ^ $xor) } unpack 'C*', $text;

   # Check if xor key is acceptable
   my $accept = 1;
   foreach my $char (@encoded_char)
   {
      if( ord($char) < 33 ||     # Reject control characters
          ord($char) >= 127 ||   # Reject extended characters
          $char eq '"' ||        # Reject non-quote friendly characters
          $char eq '\\' )
      {
         $accept = 0;
         last;
      }
   }

   # Check if encoded string contains trigraphs/digraphs
   my $encoded_str = join '', @encoded_char;
   if( index($encoded_str, '??') >= 0 ||
       index($encoded_str, '<:') >= 0 ||
       index($encoded_str, ':>') >= 0 ||
       index($encoded_str, '<%') >= 0 ||
       index($encoded_str, '%>') >= 0 ||
       index($encoded_str, '%:') >= 0 ||
       index($encoded_str, '%:%:') >= 0 )
   {
      $accept = 0;
   }
   if( $accept )
   {
      print "\n$xor\n$encoded_str\n";
   }
}


__DATA__
"
},

n[1<<16], t[1<<16],
y, *u, *i, *a;
int l, _;

#include<stdio.h>

int main()
{
   a = n;
   y = 5;
   for(u = c[5]; *u; u++)
      if( *u - 32 )
      {
         for(i = c[*u - 98]; *i; i++)
            if( *i - 32 )
               *a++ = *i ^ y;
         y ^= 5;
      }

   _ = l; u = n; a = t; i = c[2 //**/ 2
   ];
   for(; *i; i++)
   {
      if( (l = *i) > 93 )
      {
         l = (l - 94) * 4 + 2;
         for(_ = 6; _--;
             *a++ = ((l /= 2) & 1)
                ?  (y ^= (*u - 34) ? 0 : 1)
                   ? *u++ : *u++
                : 32);
      }
      if( l > 66 )
         for(l -= 66; l--; *a++ = *u++)
            y ^= *u - 34 ? 0 : 1;
      if( l > 34 )
         for(l -= 34; l--; *a++ = 32);
      if( l == 33 )
      {
         if( y )
         {
            *--a = 92;
            a++;
            u--;
         }
         *a++ = 10;
      }
   }

   *a = 0;
   return puts(t);
}