dol@ с iPad
> 2 мая 2016 г., в 16:26, Pavel Shatov <meisterpa...@yandex.ru> написал(а): > > 02.05.2016 10:43, Fredrik Thulin пишет: >> On Monday, May 02, 2016 12:37:50 AM Paul Selkirk wrote: ... >>> The AVR has to do approximately the following: - receive a tamper >>> interrupt from an external circuit (currently a panic button) - >>> wipe the MKM - raise an interrupt on the ARM, so it can do whatever >>> it needs to do - light an LED (red, of course) >>> >>> If we get that right, we might never have to upgrade the AVR. >> >> I agree. I would consider it nice to have (or harmful =) ) to have a >> software upgrade path for the AVR before Berlin. We could absolutely >> make a way to transfer firmware to the AVR from the FPGA using >> GPIOs, but with close to zero benefit at this stage. > > I think, some people will even object to DFU option being present for the > tamper detection block. What if malicious user crafts dummy tamper detection > firmware, that only lights the red panic LED, but skips actual wiping of the > secret key? > Agree... It is really dangerous to implement this I pen hurry and without real understanding attack vectors. >> My reasoning: >> >> The whole tamper circuitry is currently a development module. It is >> nice to have a way to erase any keys in the device when re-purposing >> it or similar, but it currently requires pressing a button on the >> bottom side of the PCB. If someone wants to actually add tamper >> protection to the Alpha using the AVR GPIOs, it is not unreasonable >> to expect them to program the AVR using an ISP programmer connected >> to the programming header. > > I agree that if someone wants to customize the tamper detection block, he > will most probably know how to deal with the hardware part (add new sensors > to board, support them in the tamper detection firmware, etc), so he will > definitely have AVR programming cable and won't need the DFU option. > >> >> So the main reason to make DFU for the AVR I can see would be to >> streamline manufacturing, and I think we have other things to focus >> on first. >> >> /Fredrik > > > -- > With best regards, > Pavel Shatov > _______________________________________________ > Tech mailing list > Tech@cryptech.is > https://lists.cryptech.is/listinfo/tech _______________________________________________ Tech mailing list Tech@cryptech.is https://lists.cryptech.is/listinfo/tech
