Product Certifications; Table 8. Basic Feature Differences Of Trustzone-Based Secure Software - ST STM32C0 Series Application Note

RoT services
Cryptographic key management
Secure storage
Both alternatives are based on TF-M and MCU boot, but while SBSFU intends to replicate familiar features of
X-CUBE-SBSFU while retaining most flash memory space for user code, TF-M offers more functionality. Some
of that can be dropped to gain memory space. For the STM32H57x line, the Secure manager, a closed-source
implementation of TF-M, offers a convenient and express way to adopt certified secure solutions.
5.5

Product certifications

Different secure applications often require certain certifications, proving their capability to perform in a secure
manner. Independent or government agencies grant the certification status to either an MCU application or a
combination of MCUs with secure firmware after testing it against the evaluation goals.
The certifications and evaluations related to STM32 microcontrollers include, but are not limited to:
• PSA certified (platform security architecture), governed by Arm, focused on IoT security, MCU certification,
three levels of assessment
– STM32L4 devices are certifiable up to Level 1.
– STM32L5 devices with TF-M are certifiable up to Level 2.
– STM32U5 and STM32H5 devices with TF-M are certifiable up to Level 3.
– To achieve Arm PSA certifiable security level, refer to the user manual STM32U585 security
guidance for PSA Certified™ Level 3 with SESIP Profile (UM2852).
• SESIP (security evaluation standard for IoT platforms), international methodology adopted by several major
security evaluation labs, five levels
– Systems using SBSFU or TF-M are compliant to Level 3 with STM32L4, STM32L4+, STM32L5,
STM32H5, and STM32U5 devices.
• PCI (payment card information), important security standard focusing on point of sale (POS) applications
– Good record of successful evaluation of systems using for example STM32L4 devices
AN5156 - Rev 8
Table 8. Basic feature differences of TrustZone-based secure software
Feature
NV counter
SBSFU for TrustZone®
Immutable RoT
Static keys only
Absent
No
AN5156
Product certifications
TF-M
Immutable RoT + updatable RoT
Key storage hierarchy with HUK root key
Internal and external
Yes
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