my $plaintext;
my $ct;
my $key = 'A';
while ( 1 ) {
   $plaintext = RC4($key, $ciphertext);

   if ( $plaintext !~ /[\x80-\xFF]/ ) {
      print "matched using key:$key \n";
      print "$plaintext \n";
   }
   
   if ( ++$ct == 10000 ) {
      $dt = localtime;
      print "[$dt] count: $ct key: $key \n";
      $ct = 0;
   }

   $key++;
}