Encrypt Backup

local tArgs = {...}
local h
local file = tArgs[1]
local data

if fs.exists(shell.resolve(file)) then
    h = fs.open(file,'rb')
else
    error()
end

local l = fs.open("tmp",'w')
local str = ""

while true do
  data = h.read()
  if data then
    if tArgs[2] == "c" or nil then
      data = data - 5
    elseif tArgs[2] == "p" then
      data = data + 5
    end
        str = str..string.char(data)
  else
    break
  end
end

l.write(str)
l.close()

function replace()
  h = fs.open(file,'w')
  l = fs.open("tmp",'rb')
    local str = ""
  while true do
    local dat = l.read()
    if dat then
      str = str..string.char(dat)
    else
     break
    end
  end
  l.close()
  h.write(str)
  h.close()
end

replace()