k, here is a fixed one.
checked from non-matching tests that jens' cipher is screwed up.
second test, not lcase chars:
K+K-first word = W not 5
I+I-first word = S not 1

so, this seemed to work correctly:
Code:
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  $r = instr($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



KiXtart
KiXtart Version  = 4.22
KiXforms Version =
KiXGolf Script   = kixgolf_vigenere.kix
 
Computer
OS               = Windows 2000 Professional
CPU              = Intel Pentium III Mobile
Speed            = 933 MHz
Memory           = 256 MB
 
KiXGolf Scoring Engine
Scoring Engine   = 3.0.3
 
KiXtart Golf Score
Tournament       = KiXtart Golf: Vigenere Cipher
Valid Cipher Ops = 7 (64%)
Processing Start = 2004/08/02 16:03:15.847
Processing End   = 2004/08/02 16:03:19.973
Duration         = 0000/00/00 00:00:04.125
KiXGolf Score    = 367
 
Thank you for participating in KiXtart Golf!
press any key to close
_________________________
!

download KiXnet