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)
   $k = right($k,-1)+$
   $y = instr($p,$)
  until $y
  $ = substr($t,$j,1)
  $o = ($o+($=" "))*(0=instr('!?.',substr($t,$j-1,1)))
  $r = instr($p,$)
  if $r
   $ = 62 - (ucase($t+$k)=$t+$k)*26
   $ = substr($p,1+($+$r+(2*($d=0)-1)*($y-$o-2)-1) mod $,1)
  endif
  $vigenere = $vigenere + $
  next
endfunction