Pseudo Random Number Generator using ARC4(?) cipher

[xcoder]

Print "##############################################"



msg$ = "" 'empty input string for testing PRNG key stream

code$ = "AAE1E2E3FF" 'hex$

for i = 1 to len(code$)step 2

chunk$ = mid$(code$,i,2)

print chunk$,

byte = hexDec(chunk$)

print byte

key$ = key$ + chr$(byte)

next i

call KSA key$

print

RC4$ = PRGA$(msg$)

'print RC4$

print:print

print "End of Code"

End



sub KSA key$

dim S(256)

dim K(256)

i = 0

j = 0

for i=0 to 255

S(i)=i

next i

for i = 0 to 255

K(i)= asc(mid$(key$,i mod len(key$)+1))

next i

for i = 0 to 255

j = (j+ S(i)+ K(i))mod 256

temp = S(i)

S(i)= S(j)

S(j)= temp

next i

end sub

'-------------------------------------------------

function PRGA$(msg$)

j = 0

x = 0

do while 1 'to generate keystream/no msg$

x = x + 1

if x > 2^10 then exit do 'for testing

byte = asc(mid$(msg$,x,1)) 'equal zero because no msg$

j = (j + S(i))mod 256

temp = S(i)

S(i) = S(j)

S(j) = temp

k = (S(i) + S(j))mod 256

cipher = byte xor k

ascii$ = ascii$ + chr$(cipher)

loop

' print ascii$

' PRGA$ = ascii$

PRGA$ = text2Hex$(ascii$)

end function





function text2Hex$(txt$)

for i = 1 to len(txt$)

hex$ = dechex$(asc(mid$(txt$,i,1)))

fullHex$ = fullHex$ + right$("0" + hex$, 2)+ space$(2)

next i

ctr = 0

for x = 1 to len(fullHex$) step 64 '16 * 32 *32

chunk$ = mid$(fullHex$,x,64)

print ctr,chunk$

ctr = ctr + 1

next x

end function