Hi monks, this is my first post. 
# Global mode (pretty slow on large files)
$_=q qrea ncJertsa ,thelhPkour q,my $i=length;
while($i){s/(.{$i})(.)/$2$1/g;--$i}print+$_.$/

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# Non-global
$_=q qnPteorJlt  hhascekaerru, q,my $i=length;
while($i){s/(.{$i})(.)/$2$1/;--$i}print+$_.$/;

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# Opposite code:
$_=q qJust another Perl hacker,q;until($i eq
length){s/(.)(.{$i})/$2$1/g;++$i}print+$_.$/

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It's very simple and easy to understand. Note: for files should be added '/s'

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Re: Length obfuscation
by emilbarton (Scribe) on Aug 29, 2011 at 17:01 UTC

    Hi, I found your obfuscation nice and I was asking myself why it should be so simple and easy to understand. So I treated it permutationally and I propose the following de-obfuscation. It does not look much clearer unfortunately.

    There's a little problem in this code too: the seed for translation (right shift $tran=6012345) is not in itself obtained permutationally.

    P.S. the script should print:

    another--<->
ranothe--r<->anothe
hranote--h<->ranot
ohrante--o<->hran
aohrnte--a<->ohr
haornte--h<->ao
ahornte--a<->h
ahornte

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    #!/usr/bin/perl


$_=q qanotherq, my $l=length;
while($l){s/(.{$l})(.)/$2$1/;--$l; print+$_."--".$2."<->".$1."\n"}; 

## De-obfuscation:
print &deobf("another")."\n";

sub deobf {
  my $n = 0; my (@tran,$res);
  my %h = map { $n++ => $_ } (split //,shift);
  while ($n > 0) { $n--; $res = $n.$res ; }
  $tran = $res; $tran =~ s/(.+)(.{1})/$2$1/; ## The shift seed. 
  ## print "tran: $tran\n";
  for ($n = 0; $n < length($res)-1; $n++)  { 
     $res = &comp(&perm($tran,$res),$n) 
  }
  return join('',map{ $h{$_} } (split //,$res));
} ## END deobf()

sub perm { 
    my ($target,$agent) = @_; ## Max. base (string length) = 10.
    my @targ = split //,$target;## Digital permutations only..
    my @perm = split //,$agent; ## e.g. 021, 3102, etc..  
    my $res; ## but not 031, 123, ... nor 0123456789A,..
    for (my $i = 0; $i < (@perm); $i++){ $res .= $perm[$targ[$i]] }
    return $res;
} ## END perm()

sub comp {
  my ($res, $pos) = @_;
  if ($pos > 0){
    my @perm = split //,$res; 
    my $l = scalar(@perm);
    my $p1a = $perm[0];
    my $p1b = $perm[$l-$pos];
    $perm[0] = $p1b; $perm[$l-$pos] = $p1a;
    for (my $n = 0; $n < $pos; $n++){
      my $p2a = $perm[$l-1]; 
      my $p2b = $perm[$l-$n-1];
      $perm[$l-1] = $p2b; $perm[$l-$n-1] = $p2a;
    }
    $res = join '', @perm;
  }
  return $res;
} ## END comp()

1;

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Re: Length obfuscation
by Marshall (Canon) on Oct 29, 2011 at 15:27 UTC
    No your code is not easy to understand.
    There is no question.
    What are you attempting to do?
    What is your purpose of this post?
[reply]
      It's an obfuscation. ;)
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