AN3429 Datasheet, PDF (1/5 Pages) STMicroelectronics – STM32 proprietary code protection overview

AN3429
Application note
STM32 proprietary code protection overview
Introduction
Software providers are developing complex middleware solutions (Intellectual Propriety (IP)
code), which needs to be protected.
This IP code must be available as a plug-in in the end-user applications to build the
complete solution. The global protection mechanism limits access to it via a dedicated
application programming interface (API), while preventing any read access.
This application note provides an overview of the mechanism used to protect proprietary
code from possible read out by the end-user code, debugger tools or RAM Trojan code. This
mechanism provides a full API so the IP code can be easily called by the end-user
application and still be protected against direct access to the IP code itself.
The proposed solution is based on the MPU features and a special memory and peripheral
management mechanism from the end-user application and the IP code.
In the STM32 proprietary code protection method, two levels of protection are used:
● Global Read Out Protection (Global ROP): IP code and end user code are protected
against direct reading (by debugger tools or RAM Trojan code) through STM32 ROP.
● IP code Read Out Protection (IP ROP): IP code protected against end user code
(possible Trojan code) through the MPU.
As, once the global ROP is activated, the user no longer has full control of the Flash for
programming, the primary application (IP code) must also embed an IAP Layer. This IAP
allows loading the end-user application without compromising the protected code area.
For more details about the complete solution, please contact your local ST sales
representative.
July 2011
Doc ID 019008 Rev 1
1/5
www.st.com