-- XOR cipher. -- We can count up to 256 -- Valid interval: (32;255] local function compute_hash(s) local p = 31 local m = 1e9 + 9 local hash_value = 0 local p_pow = 1 for i=1, #s do local c = string.byte(s:sub(i,i)) hash_value = (hash_value + (c - string.byte('a') + 1) * p_pow) % m p_pow = (p_pow * p) % m end return hash_value end local function toBits(num,forced_size) local bits_reversed = {} if type(num) == "string" then num = compute_hash(num) end while num > 0 do local bit = num%2 bits_reversed[#bits_reversed+1] = bit num = math.floor(num/2) end local bits = {} for i = #bits_reversed,1,-1 do table.insert(bits,bits_reversed) end
if forced_size then
while forced_size > #bits do
table.insert(bits,1,"0")
end
end
return table.concat(bits)
end

local function toDec(bits)

local bit_size = #bits
local binary_map = {}
for bin = bit_size-1,0,-1 do
table.insert(binary_map,2^bin)
end

local dec = 0
local counter = 1
for bit in bits:gmatch(".") do
if bit == "1" then
dec = dec+binary_map[counter]
end
counter = counter+1
end

return dec
end

local function xor(a,b)
return bit.bxor(a,b)
end


--Encryption and Decryption Algorithm for XOR
local function E(str,cipher)
cipher = cipher or "10010001"
local byte_list = {}
--Characters to bytes
for char in str:gmatch(".") do
table.insert(byte_list,string.byte(char))
end
local xor_list = {}
for _,num in pairs(byte_list) do
--Bytes to numbers
local cipher_num = toDec(cipher)
--Numbers to XOR
local num_xor = xor(num,cipher_num)

local char = string.char(num_xor)
table.insert(xor_list,char)
end
return table.concat(xor_list,"")
end

return {
E = E,
toBits = toBits,
toDec = toDec,
}