Some additional checks related to secure version of the application in
anti-rollback case have been added to avoid any attempts to boot lower
security version but valid application (e.g., passive partition image).
- Read secure_version under sha256 protection
- First check has been added in the bootloader to ensure correct secure
version after application verification and loading stage. This check
happens before setting up the flash cache mapping and handling over
the final control to application. This check ensures that application
was not swapped (e.g., to lower security version but valid image) just
before the load stage in bootloader.
- Second check has been added in the application startup code to ensure
that currently booting app has higher security version than the one
programmed in the eFuse for anti-rollback scenario. This will ensure
that only the legit application boots-up on the device for
anti-rollback case.
