secure boot on the nRF52840

[Wendel]

Hi Team

From what I learned, the BPROT or ACL can protect the bootloader can not be modified by the application.

But is there any way to protect the chip from erased with "nrfjprog -f nrf52 --eraseall"? Because if the bootloader can be erased, the public key/ the root of trust was broken.

Waiting for your reply. Thanks a lot.

[Wendel]

Besides, the comment of NRF_BL_APP_SIGNATURE_CHECK_REQUIRED in sdk_config.h is "Perform signature check on the app. Requires the signature to be sent in the init packet.", does that means the signature check happened after DFU?

Can I combine the init packet with bootloader+softdevice+application+bootloader setting, and program it into the chip directly?

[Sigurd]

Hi,

But is there any way to protect the chip from erased with "nrfjprog -f nrf52 --eraseall"?

No. If someone have access to the SWD pins, they can use a debugger to erase the chip.

Wendel said:

does that means the signature check happened after DFU?

The NRF_BL_APP_SIGNATURE_CHECK_REQUIRED setting is to require signature Boot validation. Signature is checked on each boot.

You might find these cases interesting:

https://devzone.nordicsemi.com/f/nordic-q-a/70726/how-to-validate-signature-check-requirements

https://devzone.nordicsemi.com/f/nordic-q-a/74838/dfu-error-invalid_parameter-after-uploading-of-all-packets-via-dfu/

Wendel said:

Can I combine the init packet with bootloader+softdevice+application+bootloader setting, and program it into the chip directly?

You are not flashing the init packet, but you can merge bootloader+softdevice+application+bootloader setting into a hex-file, and program it directly, yes.

 

 

 

 

[Wendel]

Thanks for your reply.

[Wendel]

Hi Sigurd

Sigurd said:

No. If someone have access to the SWD pins, they can use a debugger to erase the chip.

Is there any solutions to disable the SWD pins? 

[Sigurd]

Wendel said:

Is there any solutions to disable the SWD pins? 

 No. It's not possible to disable it in such a way that it prevents a debugger the possibility to trigger a erase-all operation.