cipher

local function split(self, sep)
    local sep, fields = sep or ":", {}
    local pattern = string.format("([^%s]+)", sep)
    self:gsub(pattern, function(c) fields[#fields+1]=c end)
    return fields
end

function encode(text, key)
    local chars = {}
    for i=1, #text do
        chars[i]=text:sub(i, i)
    end
    local rand_num = 1
    for i=1, #key do
        rand_num=rand_num+string.byte(key:sub(i, i))
    end
    local coded = ""
    for _, v in pairs(chars) do
        coded=coded..":"..tostring(string.byte(v)*rand_num)
    end
    return coded:sub(2)
end

function decode(text, key)
    local rand_num = 1
    for i=1, #key do
        rand_num=rand_num+string.byte(key:sub(i, i))
    end
    numbers = split(text, ":")
    final = ""
    for _, v in pairs(numbers) do
        if tonumber(v)==nil then break end
        final=final..string.char(tonumber(v)/rand_num)
    end
    return final
end