function vigenere($t,$k,optional $d)
dim $j,$r,$,$p,$o,$y
 for $j = 65 to 90
  $ = chr($j)+$+chr($j+32)
 next
 $p = "0123456789"+$
 for $j = 1 to len($t)
  do 
   $ = left($k,1)
   $k = substr($k,2)+$
   $y = instr($p,$)
  until $y
  $ = substr($t,$j,1)
  $o = $o+($=" ") -$o*(0<instr('!.?',$))
  $r = instr($p,$)
  if $r
   $ = 62 - (ucase($t+$k)=$t+$k)*26
   $=substr($p, (iif($d,$-$y,$y)+$r+o-1) mod $+1,1)
  endif
  $vigenere = $vigenere + $
  next
endfunction