Hello, You have not come across anyone on the project with the bootloader encrypted transfer fw, for STM32?
I'm not sure whether the answer is Yes, or No, can you try again in English?
Don't cloud the problem with tying it to the STM32, the concept of boot loaders and encryption are reasonably portable. The uniqueness would come about how to send/receive characters on the USART, or USB peripherals specific to the STM32.
I've written a lot of loader and update code, handling image validation, compression and encryption. Commercially developed code doesn't tend to show up in Google searches.
www.lmgtfy.com