Set APPROTECT bit on nRF9160

RE: Set APPROTECT bit on nRF9160

NelsonGoncalves — Thu, 06 May 2021 12:43:11 GMT

Thanks for the tip Markus.

I will try the guideline, and if it does not work we will need to set the bit during production.

Best regards,

Nelson

RE: Set APPROTECT bit on nRF9160

Albrecht Markus Schellenberger — Thu, 06 May 2021 12:09:43 GMT

Hello again Nelson,

I just got confirmed that the UICR register only has read access from non-secure code.

It is however possible to define own secure functions in SPM that can be called from the non-secure domain.

Unfortunately, we do not have any concrete example for that. But there is a guideline written approximately one year ago, which might help you get an idea of how you can write such a function.

I hope this will help you!

Regards,

Markus

RE: Set APPROTECT bit on nRF9160

NelsonGoncalves — Tue, 04 May 2021 17:07:42 GMT

Thanks Markus.

As is it stands, the best a non-secure app can do is to read the UICR and refuse to run if the APROTECT bit is not set.

Best regards,

Nelson

RE: Set APPROTECT bit on nRF9160

Albrecht Markus Schellenberger — Tue, 04 May 2021 13:32:28 GMT

Hello Nelson,

According to chapter 4.4.4 in the nRF9160 product specification, you are not allowed to access the UICR register from non-secure code.

There is however a secure services library which makes secure firmware functions available from non-secure firmware. Unfortunately, writing to the UICR register is not included.

I will do some internal research and get this confirmed!

Regards,

Markus