CONFIG_BOOT_ECDSA_CC310 Depricated. Suggested alternative increases size drastically.

[jumana]

When transitioning from ncs v3.3.0 to ncs v3.4.1 noticed a warning about CONFIG_BOOT_ECDSA_CC310 being depreciated when building MCUboot. The release notes suggest using PSA which I assume is CONFIG_BOOT_ECDSA_PSA. With further research I had to enable all these to compile. 

CONFIG_PSA_CRYPTO=y

CONFIG_PSA_CRYPTO_DRIVER_OBERON=n

CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y

CONFIG_PSA_USE_CC3XX_CIPHER_DRIVER=n

CONFIG_PSA_USE_CC3XX_AEAD_DRIVER=n

CONFIG_PSA_USE_CC3XX_MAC_DRIVER=n

CONFIG_PSA_USE_CC3XX_KEY_AGREEMENT_DRIVER=n

CONFIG_PSA_USE_CC3XX_ASYMMETRIC_ENCRYPTION_DRIVER=n

Source directory for mcuboot is ncs\v3.4.1\bootloader\mcuboot\boot\zephy. Using sysbuild to build along two other images. MCUboot parition size was originally set at 32kB only with deprecated config was only using 25kb with PSA it is at 46kB. Is there a better alternative to this to reduce space on the suggested approach and keep it in the original 32KB partition space?

I also noticed that sample at \v3.4.1\nrf\samples\mcuboot\firmware_loader_entrance also displays this depreciated warning. 

[Vidar Berg]

Hello,

For the bootloaders, we used PSA core lite (CONFIG_PSA_CORE_LITE) which has a much smaller footprint. Unfortunately, it does not support the CC310 backend with the bootloader variant of the CC310 runtime library, so you must use the standard variant, which has a significantly larger footprint. PSA core lite supports HW accelerated crypto only on the nRF54 series. As a result, the current PSA Crypto integration doesn't match the footprint of the previous bootloader crypto libraries. Because of this, I would recommend you continue using CONFIG_BOOT_ECDSA_CC310 even though it has been market as deprecated. I have reported this limitation internally. Please also note that nRF Connect SDK v3.4.x is the last release to include nRF52 series support, so the deprecation will not affect your device (https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/nrf-connect-sdk-gets-long-term-support-with-version-3-4-0).  

Best regards,

Vidar