Application file encryption (.bin)

RE: Application file encryption (.bin)

bjorn-spockeli — Tue, 26 Sep 2017 08:24:14 GMT

@nicolagallazzi: If you're concerned with the efficiency, then you could as Emil suggests, use the ECB-AES peripheral in CTR mode to encrypt the firmware. See this blog post for an example.

RE: Application file encryption (.bin)

Nicola Gallazzi — Fri, 22 Sep 2017 12:37:12 GMT

Thanks again Bjorn, I've updated my question with more details

RE: Application file encryption (.bin)

bjorn-spockeli — Fri, 22 Sep 2017 10:43:48 GMT

YEs, micro-ecc is good choice as we already use that library in the SDK, we provide an abstraction called nrf_crypto, see this Infocenter page for more information.

RE: Application file encryption (.bin)

Nicola Gallazzi — Fri, 22 Sep 2017 09:42:59 GMT

Thanks a lot Bjorn,

do you suggest a way to encrypt the application file in order to easily decrypt it on the firmware side? A symmetric algorithm would be a good choice? We read something about MicroEcc, could it possibly be a valuable choice?

Thanks and regards,

Nicola Gallazzi

RE: Application file encryption (.bin)

bjorn-spockeli — Fri, 22 Sep 2017 09:34:52 GMT

Hi Nicola,

you are correct, nrfutil will only sign the firmware image using the provided private key so that autenticity of the firmware image can be verified on the nRF side using the corresponding public key.

The conversion of the application .hex file to a .bin file does not contain any encryption procedure, i.e. the .bin file will be unencrypted.

Best regards

Bjørn