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irk as the only security perimeter

Stanislav Silnitskiy

Hello, Nordic!

In our entertainment project, nrf51 based devices exclusively utilizes either central or periph. role. All of them are headless (body mounted markers, etc). The environment is hostile (in the sense, that some cheater could spoof device address, advertising it as valid periph.) Besides, we don't need a connection at all, and wish to relay upon pre-shared set of IRKs, belonging to peripherals. What we need is just RSSI and some extra info in advert.

Is it right case to use private addresses for? If so, which API does sdk provide to hash/rehash the address in central and how IRK is being set in peripheral?

I tend to use S130 and if it is redudant for scenario explained, I'd appreciated an advice.

Stan

  • 0 in reply to Hung Bui

    Hi Stan,

    You can apply a white list when doing scanning. It's inside ble_gap_scan_params_t when calling sd_ble_gap_scan_start.

    But we don't support too many IRKs in the whitelist at a time, max 8 I believe. The stack will handle the resolving and only advertising packet from advertiser with correct IRK will be notify to the application. If you want more you may need to handle the address solving in the application.

    What you described may work. My only concern is that it only work if all packets are received correctly to the scanner. If the attacker jam the signal, and then use the old address(es) (that the scanner couldn't receive) and advertise with modified data, then you may have a trouble.

    What about keeping the address fixed, but encrypting your advertising data instead of the address ?

  • 0 in reply to Hung Bui

    OK! thank you very much for opposing my ideas, I will consider it in implementation! Indeed, the answer for initial question (is using IRK fits proposed scenario?) has to be negative, I suppose.

  • 0 in reply to Hung Bui

    Hi Stan, Yes, it's possible to use the IRK as the whitelist for the scanner (with the limit of 8 IRK at a time as mentioned).

  • 0 in reply to Hung Bui

    Hi Hung, do I understand right, that IRK infrastructure implemented at hardware level?

  • 0 in reply to Hung Bui

    Is it possible to distinguish which IRK the address from recent received adv. packet belongs to? For the scenario, there are a several IRKs in use be infrastructure of beacons?

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