Secret keys protection method for microcontrollers, based on special hardware blocks using

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Lviv Polytechnic National University, Computer Engineering Department

The proposed article demonstrates how to protect some memory areas in STM microcontrollers, what could be used for secret cypher keys storing, by using special hardware block “Firewall”. This method provides access to predefined microcontroller’s memory areas form configured in “Firewall” address space and blocks access from another program memory space. Since, STM microcontrollers provides connection to external Flash and SRAM for address space expanding, memory protection with “Firewall” was investigated when unauthorized code from external memory tries to get access to protected memory areas.

  1. RM0351 Reference manual, STM32L4x5 and STM32L4x6 advanced Arm-based 32-bit MCUs ./
  2. AN4729 Application note, STM32L0/L4 FIREWALL overview./
  3. AN4758: Proprietary code read-out protection on microcontrollers of the STM32L4 Series./