uECC encrypto not really needed for secure bootloader?

[cpeng]

from this guide

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/getting-started-with-nordics-secure-dfu-bootloader#h23sjziacp7vrw0scs2t3tua1ax0426

It is suggested the crypto method used for secure bootloader project is micro ECC, hence step B1 with all the micro ECC library setup and stuff.

However I discovered there are quite a few crypto method options in sdk_config.h inside the bootlaoder project. See the picture below:

The default one is this CC310 BL something shown in the picture.

And secure DFU process has been just fine with this crypto method selected.

So I wonder is uECC really necessary? What's the recommended crypto by Nordic? What are those other methods and why are they there?

Thanks.

Edit: for some reason i cant get the uploaded picture to show up. Could be a forum problem

[Einar Thorsrud]

Hi,

As you mention, the bootloader can use several different crypto backends for signature verification. Originally, micro ECC was the only option, and for a long time, you needed to download it in order to build the bootloader projects even if another backend was used. Since SDK 15, CC310 BL is the default backend on the nRF52840, and micro ECC is the default backend on the other devices. There are other crypto libraries integrated with nrf_crypto as well, but these increase the size of the bootloader significantly without providing any benefits. So my recommendation is to use CC310 BL if you are using the nRF52840.

Thank you for mentioning the picture upload issue. This has been reported earlier and is currently being looked into.

[cpeng]

Thanks for your clarification! it's very helpful. Yes I use nRF52840DK, So I will keep using CC310 BL as the crypto method.