NBU image update in KW45 processor

[Chan_17]

Hi NXP Team,

We are working with a raw K45 MCU where the keys are currently set to null, and the NBU image has not yet been flashed. We plan to flash an unsigned .sb3 image, which is unencrypted.

We have the following queries:

1. Key Provisioning:

Could the NXP team please confirm whether key provisioning is required in this scenario, considering that we are flashing an unsigned (unencrypted) .sb3 file?

2. Creating Unsigned .sb3 File:

How can we generate an unsigned .sb3 image? Is there any official reference, example, or documentation available perhaps within the SDK that explains this process?

We would appreciate it if you could provide relevant guidance or documentation links or SDK example.

[luis_maravilla]

Hello

I would strongly not recommend using unsigned sb3 image as KW45 can possibly enter in secure lifecycle state and can brick the device alongside there is not supported documentation for unsigned sb3 files. Sorry for the inconveniences.

I would recommend following the AN14003 Programming the KW45 flash for Application and Radio firmware as Chapter 5.2.1 described that its mandatory for KW45 chips to update with SBKDK and RoTKTH keys in the fuse. otherwise updating a sb3 file would fail.

Best Regards

Luis

[Chan_17]

Thank you! Luis for confirmation.