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XOR Cipher in Lua. See comments for more information.
cipher = "10101111" -- must be eight digit binary number
--Returns the XOR of two binary numbers
function xor(a,b)
local r = 0
local f = math.floor
for i = 0, 31 do
local x = a / 2 + b / 2
if x ~= f(x) then
r = r + 2^i
end
a = f(a / 2)
b = f(b / 2)
end
return r
end
--Changes a decimal to a binary number
function toBits(num)
local t={}
while num>0 do
rest=math.fmod(num,2)
t[#t+1]=rest
num=(num-rest)/2
end
--[[ t gives the binary number in reverse. To fix this
the bits table will give the correct value
by reversing the values in t.
The result will be left paddied with zeros to eight digits
]]
local bits = {}
local lpad = 8 - #t
if lpad > 0 then
for c = 1,lpad do table.insert(bits,0) end
end
-- Reverse the values in t
for i = #t,1,-1 do table.insert(bits,t[i]) end
return table.concat(bits)
end
--Changes eight digit binary to decimal
function toDec(bits)
local bmap = {128,64,32,16,8,4,2,1} --binary map
local bitt = {}
for c in bits:gmatch(".") do table.insert(bitt,c) end
local result = 0
for i = 1,#bitt do
if bitt[i] == "1" then result = result + bmap[i] end
end
return result
end
--Encryption and Decryption Algorithm for XOR Block cipher
function E(str)
--split cipher string into a table
local ciphert = {}
for c in cipher:gmatch(".") do table.insert(ciphert,c) end
--split string into a table containing only binary numbers of each character
local block = {}
for ch in str:gmatch(".") do
local c = toBits(string.byte(ch))
table.insert(block,c)
end
--for each binary number perform xor transformation
for i = 1,#block do
local bitt = {}
local bit = block[i]
for c in bit:gmatch(".") do table.insert(bitt,c) end
local result = {}
for i = 1,8,1 do
table.insert(result,xor(ciphert[i],bitt[i]))
end
block[i] = string.char(toDec(table.concat(result)))
end
return table.concat(block)
end
--Test Section
print(E("Hello World"))
print(E("çÊÃÃÀøÀÝÃË")) -- returns 'Hello World'
print(E("The quick brown fox jumps over the lazy moon"))
print(E("ûÇʏÞÚÆÌďÍÝÀØÁÉÀ׏ÅÚÂß܏ÀÙÊݏÛÇʏÃÎÕ֏ÂÀÀÁ")) -- returns 'The quick brown fox jumps over the lazy moon'
@cnxkey
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cnxkey commented Oct 14, 2021

test

@Aws0mee
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Aws0mee commented Nov 22, 2021

test

@cnxkey was the test successful?

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