ChaoCipher

PHP
1

So… i tried to implement this design, and for some reason the decypher breaks down after about… 19 letters. (‘Break down’ meaning the decypher no longer correctly produces the correct letter.)


function encypher($instring) {
  $lft = "HXUCZVAMDSLKPEFJRIGTWOBNYQ";
  $rgt = "PTLNBQDEOYSFAVZKGJRIHWXUMC";
  $lab = str_split($lft);
  $rab = str_split($rgt);
  $split = str_split(str_replace(' ','',$instring));
  $outstring = "";
  
  foreach($split AS $char) {
  //Phase 1:  Encode Character
   $x = array_search(strtoupper($char),$rab); //Current position of the letter.
   $outstring .= $lab[$x];
   
   //Phase 2: Permute Left Alphabet
   for($i = 0; $i < $x; $i++) { 
      array_push($lab,array_shift($lab)); 
   }
   $temp = $lab[1];
   for($i = 2; $i < 14; $i++) {
     $lab[$i-1] = $lab[$i];
   }
   $lab[13] = $temp;   
   
   //Phase 3: Permute Right Alphabet
   for($i = 0; $i <= $x; $i++) { 
      array_push($rab,array_shift($rab)); 
   }
    $temp = $rab[2];
   for($i = 3; $i < 14; $i++) {
     $lab[$i-1] = $lab[$i];
   }
   $lab[13] = $temp;
  }   
  return $outstring;
}

function decypher($instring) {
  $lft = "HXUCZVAMDSLKPEFJRIGTWOBNYQ";
  $rgt = "PTLNBQDEOYSFAVZKGJRIHWXUMC";
  $lab = str_split($lft);
  $rab = str_split($rgt);
  $split = str_split(str_replace(' ','',$instring));
  $outstring = "";
  
  foreach($split AS $char) {
  //Phase 1:  Decode Character
   $x = array_search($char,$lab); //Current position of the letter.
   $outstring .= $rab[$x];
   
   //Phase 2: Permute Left Alphabet
   for($i = 0; $i < $x; $i++) { 
      array_push($lab,array_shift($lab)); 
   }
   $temp = $lab[1];
   for($i = 2; $i < 14; $i++) {
     $lab[$i-1] = $lab[$i];
   }
   $lab[13] = $temp;   
   
   //Phase 3: Permute Right Alphabet
   for($i = 0; $i <= $x; $i++) { 
      array_push($rab,array_shift($rab)); 
   }
    $temp = $rab[2];
   for($i = 3; $i < 14; $i++) {
     $lab[$i-1] = $lab[$i];
   }
   $lab[13] = $temp;
  }   
  return $outstring;
}

$x = encypher("Moo cow jump quick black fox");
echo $x;
echo "<br>".decypher($x);

Outputs:


YSDBDKIFFUMTFFZMALDZPPF
MOOCOWJUMPQSGJZSSHIKPTN

any idea where i’ve screwed up?

EDIT: Teach me to be lazy. Spotted the error. Permuting the right alphabet i forgot to update $lab into $rab.