Help!!!

[Polter]

Actually, now, I have made this program implementing the vigenere alogarithms which follows:

NOTE:
c = cipher
p = plain
k = key

to encrypt:

C = (P+K) MOD 26

to decrypt

P = (C-K+26) MOD 26


Here's the code:



CLS


LOCATE 1, 1
INPUT "ENTER WORD: "; WORD$
WORD$ = UCASE$(WORD$)
LOCATE 1, 15
PRINT WORD$
INPUT "ENTER KEY : "; KEY$
KEY$ = UCASE$(KEY$)
LOCATE 2, 15
PRINT KEY$

Y = 0
P = 0
K = 0
C = 0

FOR X = 1 TO LEN(WORD$)

Y = Y + 1

IF Y > LEN(KEY$) THEN Y = 1

P = ASC(MID$(WORD$, X, 1)) - 65
K = ASC(MID$(KEY$, Y, 1)) - 65

C = (P + K) MOD 26

CIPHER$ = CHR$(C + 65)
CIPHER$ = CIPHER$ + OCIPHER$

OCIPHER$ = CIPHER$

NEXT

PRINT "CIPHER :"
LOCATE 3, 15
PRINT CIPHER$

YY = 0
PP = 0
CC = 0
KK = 0



It works, but only alphabetic characters can be used, not even space....
I'm still in trouble finding out how to decrypt... I've tried the formula, but it still outputs garbled plaintext....


here's where i got my idea
britanica encyclopedia (old book at my high school library)
http://en.wikipedia.org/wiki/Vigenere_table

I'll try to expand the charset of the proram to use the whole ASCII charset....