[OpenTRV-dev] FAQ 11: is it safe to do without the CRC on secure frames?

[Jeremy Poulter]

If you are short on space then definitely drop it. Your security layer
should cover verifying the frame content, if it does not the communication
is not secure ;-)

As you have mentioned you are fixed with the AVR plus Hope RF module for
now but there are some awesome combination MCU/radio chips coming out, eg
the nRF52. Think they quoted sub 10mA when TX/Rx and the sleep power was
ridiculously low. All that and a good CPU (ARM Cortex), floating point,
Bluetooth, NFC and loads of other goodies.

Jeremy
On 19 Dec 2015 19:14, "Damon Hart-Davis" <dhd at exnet.com> wrote:

> Module CRC support is basically completely incompatible across different
> module types, so we would lock into one module type/family for ever if we
> used it.  Also it’s just not that hard to do in software.
>
> We will be able to make use of auto preamble with more use of packet
> handling with the new protocol.  The packet length that we will be using is
> about the only portable feature but should help a lot.  Patience,
> patience!  B^>
>
> Rgds
>
> Damon
>
>
> > On 19 Dec 2015, at 19:07, Deniz Erbilgin <deniz.erbilgin at gmail.com>
> wrote:
> >
> > I still find it amusing that we don't use the preamble and crc that are
> built into the rfm23bs...
> >
> > Regards,
> >
> > Deniz
> >
> > On 19/12/15 19:01, Damon Hart-Davis wrote:
> >>> On 19 Dec 2015, at 18:51, Bo Herrmannsen <bo.herrmannsen at gmail.com>
> wrote:
> >>>
> >>> a spanner in the works....
> >>>
> >>> maybe we are using the wrong AVR? ie maybe we should consider a bigger
> one?
> >> We have the one that we have, and it is typical of smaller devices.
> And we aren’t able to change horses now for the valves or for Launchpad.
> >>
> >> We are likely to have to stay low-end to keep costs down for both
> projects.
> >>
> >> But in any case the issue is more to do with a combination of common
> radio module behaviour and interrupt latency; an otherwise more powerful
> MCU could even be worse.
> >>
> >> Rgds
> >>
> >> Damon
> >>
> >>
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