; begin Top Secret
;
;!
Function a($l,$b,$c,$d)
 /*
 1) the block length
 2) the permutation
 3) the message to be encoded or decoded
 4) a parameter denoting encoding (E) or decoding (D)
 */

dim $i, $o[$c^0], $, $r, $k

For $i=0 to $c^0
  $=Substr($c,$i+1,1)
  $a=LCase($)
  If $a>` & $a<}
    $k=$k+$
    $r=$r+" "+$i
  EndIf
  $o[$i] = $

  If ($k^)=$l | $i=($c^)
    for each $ in Split($b,",")
      if $i+$-($k^)<=($c^)
        $a=$a+" "+$
      EndIf
    Next
    $a=split($a)
    For $=1 to ($k^)
      $o[split($r)[iif($d=E,$,$a[$])]] = substr($k,iif($d=E,$a[$],$),1)
    Next
    redim $r,$k
    $a=join($o,'')
EndFunction
;!
;!
; end Top Secret