WARNING: Using generated NSIB public/private key-pair.

[snowuyl]

D:\ncs\v2.4.0\bootloader\mcuboot\samples\zephyr\hello-world>west build -b nrf5340dk_nrf5340_cpuapp
-- west build: generating a build system

...

-- Configuring done
-- Generating done
-- Build files have been written to: D:/ncs/v2.4.0/bootloader/mcuboot/samples/zephyr/hello-world/build/b0
=== child image b0 - end ===

CMake Warning at D:/ncs/v2.4.0/nrf/subsys/bootloader/cmake/debug_keys.cmake:36 (message):

--------------------------------------------------------------
--- WARNING: Using generated NSIB public/private key-pair. ---
--- It should not be used for production. ---
--- See CONFIG_SB_SIGNING_KEY_FILE ---
--------------------------------------------------------------

Procedures to reproduce this issue is as follows.

1. Unzipping hello-world.zip to D:\ncs\v2.4.0\bootloader\mcuboot\samples\zephyr folder.

2. cd D:\ncs\v2.4.0\bootloader\mcuboot\samples\zephyr\hello-world

3. west build -b nrf5340dk_nrf5340_cpuapp

[Sigurd]

Hi,

You need to set CONFIG_SB_SIGNING_KEY_FILE when using your own key.

See the documentation here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/config_and_build/bootloaders_and_dfu/bootloader_adding.html#adding-a-custom-signature-key-file

Based on your sample, try setting this in prj.conf:

CONFIG_SB_SIGNING_KEY_FILE="custom_key_dir/custom_priv.pem"

[Daniel K]

I tried to solve this by generating a config file using the absolute path and adding it as an overlay; but then the thing I ran into was that this message is being generated for the b0 and b0n images.

CONFIG_SB_SIGNING_KEY_FILE depends on SECURE_BOOT, which depends on !IS_SECURE_BOOTLOADER.

Therefore this config will always be undefined for b0 and b0n and always produce this error message.

What does this mean?  I don't think b0 and b0n are signed with CONFIG_SB_SIGNING_KEY_FILE, but neither should they be signed with the default key either (because what would validate the signature?).  Is hci_rpmsg signed with CONFIG_SB_SIGNING_KEY_FILE if I don't supply an absolute path for it?