--Wraps all I/O using rot13 encoding.

return {

  rot13_c = function (c)

    local a = string.byte "a"
    local z = string.byte "z"
    local A = string.byte "A"
    local Z = string.byte "Z"

    local byte = string.byte(c)
    if byte >= a and byte <= z then
      return string.char(((byte - a) + 13) % 26 + a)
    elseif byte >= A and byte <= Z then
      return string.char(((byte - A) + 13) % 26 + A)
    else
      return c
    end
  end,

  rot13 = function (self, s)
    return (string.gsub(s, ".", function (c)
        return self.rot13_c(c)
      end))
  end,

  recv = function (self)
    local line, err = self.super:recv()
    if line == nil then
      return line, err
    end
    return self:rot13(line)
  end,

  send = function (self, data)
    return self.super:send(self:rot13(data))
  end,
}