input = "According to all known laws of aviation; there is no way a bee should be able to fly. Its wings are too small to get its fat little body off the ground. The bee: of course, flies anyway because bees don't care what humans think is impossible."

math.randomseed(os.time())
key = {
  a = "%",
  b = "2",
  c = "+",
  d = "]",
  e = "@",
  f = "9",
  g = "~",
  h = "^",
  i = "`",
  j = ";",
  k = "*",
  l = "#",
  m = ")",
  n = "[",
  o = ":",
  p = "&",
  q = "i",
  r = "(",
  s = "/",
  t = "}",
  u = "7",
  v = "{",
  w = "1",
  x = "=",
  y = "_",
  z = "4",

  noise = "-",
  upper = "p",
}

key[" "] = "8"
key["."] = "5"
key[","] = "3"
key[":"] = "o"
key[";"] = "w"
key["'"] = "\""
key["!"] = "0"
key["?"] = "!"

function code(str)
  local r = ""
  for i = 1, #str do
    replaced = false
    char = string.sub(str, i, i)

    if math.random(1,5) == 1 then
     r = (r .. key.noise)
    end
    for _, v in pairs(key) do
      if string.lower(char) ~= char and string.lower(char) == _ then
        r = (r .. key.upper .. v)
        replaced = true
      elseif
        string.lower(char) == _ then
        r = (r .. v)
        replaced = true
      end
      if char == key.noise then
        replaced = true
      end
    end
    if (not replaced) then
      print("Invalid character: " .. char)
    end
  end

  return r
end

function decode(str)
  local r = ""
  for i = 1, string.len(str) do
    char = string.sub(str, i, i)

    if char ~= key.noise then
      for _, v in pairs(key) do
        if char == v then
          if v == key.upper then
            upper = true
          else
            if upper then
              r = r .. string.upper(_)
            else
              r = r .. _
            end
            upper = false
          end
        end
      end
    end
  end

  return r
end

a = code(input)
print("Coded: " .. a)
io.write("\n")
a = decode(a)
print("Decoded: " .. a)