Attaching Random Initial Vector to ARC4(?)

[xcoder]

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

global key$

code$ = "AAFFE0E1E2" 'hex$

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

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

byte = hexDec(chunk$)

char$ = chr$(byte)

key$ = key$ + chr$(byte)

next i

print " Rolling Code Stream Cipher"

print "Select an Option: "

print "Select (1) for Encrypt"

print "Select (2) for Decrypt"

print "Select (3) to quit"

input "Enter your choice: ";num



select case num

case 1

call Encrypt

case 2

call Decrypt

case 3

print "Goodbye!"

Stop

case else

print "Invalid input"

print "Program Terminated"

call quit

end select



print:print

print "End of Code"

End



sub Encrypt

iv$ = iv10$()

input "File to Read: ";file$

input "File to write: ";file2$



open file$ for input as #1

open file2$ for output as #2

txt$ = input$(#1,lof(#1))

print #2, Encode$(txt$,iv$);

close #1

close #2

for i = 1 to 6

print space$(i);"Encrypting"

next

print "------------completed----------------"

end sub



sub Decrypt

input "File to Read: ";file$

input "File to write: ";file2$

open file$ for input as #1

open file2$ for output as #2

txt$ = input$(#1,lof(#1))

print #2, Decode$(txt$)

close #1

close #2

for i = 1 to 6

print space$(i);"Decrypting"

next

print " --------------completed-------------------------"

end sub





function Encode$(msg$,iv$)

print iv$ '******************

fkey$ = key$ + iv$

print fkey$ '******************

call KSA$ fkey$

out$ = PRGA$(msg$,iv$)

Encode$ = out$

end function

'============================================================

function Decode$(out$)

ivRx$ = left$(out$,10)

print ivRx$ '******************

rfkey$ = key$ + ivRx$

print rfkey$ '******************

call KSA2$ rfkey$

in$ = PRGA2$(out$)

Decode$ = in$

end function

'=============================================================



sub KSA$ fkey$

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$(fkey$,i mod len(fkey$)+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$(msg$,iv$)

i = 0

j = 0

for x = 1 to len(msg$) 'cannot use varible i or j

byte = asc(mid$(msg$,x,1))

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)

next x

PRGA$ = iv$ + ascii$

end function



function iv10$()

for i = 0 to 9

x = int(rnd(1)* 256)

y$ = y$ + chr$(x)

next

iv10$ = y$

end function



'================== receive program ========================================



sub KSA2$ rfkey$

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$(rfkey$,i mod len(rfkey$)+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 PRGA2$(msg$)

text$ = mid$(msg$,11)

i = 0

j = 0

for x = 1 to len(text$) 'cannot use varible i or j

byte = asc(mid$(text$,x,1))

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)

next x

PRGA2$ = ascii$

end function



sub quit

'timer must be encased with a sub to function properly

timer 1000,[done]

wait

[done]

timer 0

End

end sub