Support custom private key for MCUBoot

[RAGHAV_M]

Hi,

I am new to the NRF and private-public key pair using.

Can anyone please explain me how to use custom keys for MCUBoot, I added below config in /child_image/mcuboot.conf

CONFIG_BOOT_SIGNATURE_KEY_FILE="path/to/private_key.pem"

At build, I see below error message

undefined reference to `rsa_pub_key'
undefined reference to `rsa_pub_key_len'

If I remove the config, I see below warning

WARNING: Using default MCUBoot key, it should not be used for production. 

Can anyone please guide me what wrong I am doing, or do I need add any configuration?

[Schmid]

Hello,

you may need to set:

CONFIG_BOOT_SIGNATURE_TYPE_RSA=n

CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y

depending on what you are using.

[Jared]

Hi,

What configs you should add to the project depends on how you generated the keys. But here is a sample that shows you how to use signature keys for MCUBoot. It supports up to v2.5.0,

regards

Jared 

[RAGHAV_M]

Hi Schmid,

Thank you for the response, will check the key type we are using and update the same in the config.

Meanwhile let me confirm, do we need also to provide public key path? How is the public key derived then? during build?

[Schmid]

No, you just need to provide the absolute Path to the Private Key.

You can read more about that in Lesson 8 of the NCS Intermediate Course.

[RAGHAV_M]

Thank you for the good reference, Schmid.

I now understand how secure bootloader is, still so much to learn.