It's a very simple encrypt/decrypt, but meets our level of "difficult". I need to add some error checks. And I'd like to use Exporter, but I couldn't get export_to_level to work :?

Besides that, all opinions desired!

package My::Acme::Clutter;

use 5.006;

sub encrypt {
   my $return;
   for ( split(//,shift) ) {
     $return .= sprintf("%02x",ord($_));
   }
   return $return;
}

sub decrypt {
   my $return;
   for ( $_[0] =~ /.{2}/g ) {
      $return .= chr( hex $_ );
   }
   return $return;
}

sub import {
    my $pkg = shift;
    my $callpkg = (caller)[0];
    my $string = shift;

    if ($string =~ s/^`//) {
       $string = decrypt($string);
    }
    else {
       my $clutter = encrypt($string);
       open 0 or print "Can't clutter '$0'\n";
       (my $file = join "", <0>) =~
          s{^\s*use\s+My::Acme::Clutter.*?;\n}{use My::Acme::Clutter '
+`$clutter';}m;
       open 0, ">$0" or print "Cannot clutter '$0'\n" and exit;
       print {0} $file and exit;
    }

    # turn the string into a hash
    my %args = eval $string;

    # finally, do the import;
    for my $var (keys %args) {
       ${"${callpkg}::$var"} = $args{$var};
    }
}

1;
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