Re: [TLS] Getting started, clock not set yet

[Peter Gutmann <[e-mail]>]

Kyle Rose <[e-mail]> writes:

>I wish I had some more context for this area of embedded devices. For example:
>
> * Why is an RTC more expensive (along whatever axis you choose) than a NIC
>(wifi or ethernet)?

Quoting "IoT / SCADA Crypto, What you Need to Know":

  The device often won't have any on-board time source because it's not
  feasible to include an RTC in the design. An RTC adds considerable cost
  (possibly as much as the rest of the device), may be larger/heavier than the
  rest of the device, typically requires one or more extra assembly steps to
  fit because they can't be installed via pick-and-place and reflow soldering,
  make the device more vulnerable to issues like high and low temperatures
  that embedded devices are typically exposed to, and wear out (the batteries
  die) long before the rest of the device does.

> * What classes of devices would reasonably sit on a shelf for ten years and
>subsequently prove useful without being updated?

Any number of SCADA devices.  They're an exact replacement for an existing
device, so the fact that you're replacing something that's failed with
something else that's exactly identical is a requirement.  You don't want to
replace it with something that someone's fiddled with in the meantime because
you can't guarantee that it'll behave the same as the original device did.

> * If it's been sitting on a shelf for ten years, why is reattaching it to
>the network easy, while plugging it into an upgrade klosk first and *then*
>reattaching it to the network is hard?

See my earlier comments on this.

Peter.