Secret Key Generation Based off of Physical Layer

RE: Secret Key Generation Based off of Physical Layer

Vidar Berg — Mon, 25 Feb 2019 08:31:33 GMT

You can read out the RSSI in p_ind->service.rssi for each received frame (see main.c->void mcps_data_ind(mcps_data_ind_t * p_ind))

RE: Secret Key Generation Based off of Physical Layer

Kebab — Tue, 19 Feb 2019 16:35:33 GMT

I've been looking at doing this in 802.15.4 as it seems a bit simpler. How can I implement the RSSI sampling and get each board to take 64 measurements?

RE: Secret Key Generation Based off of Physical Layer

Kebab — Mon, 18 Feb 2019 10:22:46 GMT

Ok thanks. I have seen a similar problem here but even doing this is a bit beyond me. I just don't know where to begin with adding the features I am looking for. For instance, where does the line "BLE_GAP_EVT_CONNECTED" come from or is there a source where this terminology is explained?

Sorry about all the basic questions but I appreciate the help.

RE: Secret Key Generation Based off of Physical Layer

Vidar Berg — Mon, 18 Feb 2019 10:05:01 GMT

Ok, maybe you can start with the UART central and peripheral example, then add RSSI sampling and an implementation of your own key generation. You may find this blog post useful (link) although it covers encryption with static keys.

RE: Secret Key Generation Based off of Physical Layer

Kebab — Mon, 18 Feb 2019 09:28:05 GMT

HI Vidar,

Thanks for your reply however the purpose of the project is to develop and use the method I mentioned in the original post. I cannot use any already standardized methods to generate the key.

RE: Secret Key Generation Based off of Physical Layer

Vidar Berg — Mon, 18 Feb 2019 09:14:35 GMT

Hi,

You will likely get better security if you use the built-in Random number generator and a standardized key exchange method such as "Diffie-hellman" for creating the shared secret. The ECDH Example provided in SDK 15.2.0 should be a good starting point to get an understanding of the nRF crypto API. Also, we have BLE examples that support LESC pairing (diffie helman key exchange) for securing the link. ble_app_hrs is one of the examples that supports it.