#!/usr/bin/perl

open(FILE1,"/usr/dict/linux.words");
$words="|".join("|",<FILE1>)."|";
close(FILE1);
$words=~s/[\n\r]//g;
$words=~y/A-Z/a-z/;

open(FILE1,"encrypted.txt");
$msg1=join(" ",<FILE1>);
$msg1=~s/[\n|\r]//g;
while($msg1=~s/  / /g){;}
$msg1=~y/A-Z/a-z/;
close(FILE1);

$bestfit="0";
$bestmsg="";

# ====== CAESER SHIFT ======

print "ENCRYPTED:\n";
print $msg1."\n";
print "decrypting...\n";
for($i=0;$i<26;$i++){
  $msg1=~y/a-zA-Z/b-zaB-ZA/;
  @testwords=split(' ',$msg1);
  $msgwords=@testwords;
  $msgrealwords=0;
  for $test(@testwords){
    if(index($words,$test)>0){
      $msgrealwords++;
    }
  }
  if($msgrealwords>$bestfit){
    $bestfit=$msgrealwords;
    $bestmsg=$msg1;
    print "better fit: $msg1\n";
  }
}


end:
print "\nBEST FIT:\n";
print $bestmsg."\n";
open(FILE1,">plaintext.txt");
print FILE1 $bestmsg;
close FILE1;