Bootloader and Firmware signing on STM32L452RE

[light_pirate]

I am using STM32L452RE for an application.
I want to implement firmware signing feature on the board so only authenticated firmware is allowed by bootloader to flash on the board. 
Can i conclude that mbedtls library is popular, but it cannot be used on the board since there is no hardware accelerator?
I wonder that shouldn't be the case. 

However, I saw this example library where data signing is implemented. I feel something can be done on similar lines. Please guide on how to implement this. 

https://github.com/STMicroelectronics/STM32CubeL4/tree/master/Projects/NUCLEO-L452RE/Examples/CRYP/CRYP_AESModes

[hpons]

Hi, you may want to take a look at STM32 SBSFU project.
It's already implementing SBSFU using a STM32L432 which is really simillar to the STM32L452.

It looks like someone already tried to port it here : https://community.st.com/t5/stm32-mcus-security/integrating-sbsfu-to-stm32l452ceux-using-sbsfu-package-from/td-p/296722

Here is the link to SBSFU : 
https://www.st.com/en/embedded-software/x-cube-sbsfu.html