The new STM32G5 is ST’s most secure mixed-signal microcontroller thanks, in part, to its Cortex-M33 core offering TrustZone and its support for post-quantum cryptography. This is on top of the typical security features that developers now expect on an STM32 MCU and which enable us to consistently target SESIP Level 3 and PSA Level 3 certifications. Concretely, that means engineers can meet the latest regulatory requirements without a performance penalty or additional devices. It also gives them greater control over the device lifecycle and more flexibility. Put simply, the STM32G5 offers robust, built-in security that supports current and upcoming compliance efforts.
PQC
Why get ready for post-quantum cryptography today?
Regulations from the European Commission, the American National Institute of Standards and Technology, and numerous other governmental cybersecurity agencies around the world have already voted on guidelines, regulations, or even laws mandating that computer systems support quantum-resistant algorithms. As the industry agrees that quantum threats, meaning the ability of quantum computers to break classic asymmetric cryptography, are only a matter of time, it is critical for infrastructure to be ready before quantum computers can actually cause issues. As avid readers of the ST Blog know, there are numerous implementation avenues, but all rely on having a device capable of supporting PQC algorithms.
How does the STM32G5 support PQC?
The dual-core version of the STM32G5 will be our first mixed-signal MCU to come with a hardware crypto core capable of accelerating all NIST-approved PQC algorithms, meaning LMS (Leighton-Micali Signature), a stateful hash-based algorithm, ML-KEM (FIPS 203), ML-DSA (FIPS 204) and SLH-DSA (FIPS205). ML stands for Module-Lattice. SLH stands for StateLess Hash-based. KEM stands for Key Encapsulation Mechanism and refers to how a key is used over an insecure channel, while DSA (Digital Signature Algorithm) verifies authenticity. Some of the biggest actors in the industry already use these algorithms, and they often serve as a benchmark for PQC support. The single-core STM32G5 can run all these algorithms in software.
Trust
What new regulations mean for developers?
As new regulations for modular common redundant power supplies (M-CRPS) demand that engineers use a microcontroller architecture compatible with secure boot and secure firmware updates, as defined by the Open Compute Project (OCP), it is essential for engineers to choose components that meet these stringent requirements to future-proof designs. Moreover, as the recent Security Protocols and Data Models (SPDM) standard is now regulating authentication, attestation/measurement, and key exchanges, teams must mind the additional requirements and scrutiny. In some cases, designs call for a secure element to help manage those constraints, but that increases the bill of materials.
How does the STM32G5 handle trust?
The STM32G5 series offers security services like an immutable Root of Trust (iRoT) and updatable Root of Trust (uRoT). We set the first one at the factory level. It stores keys and other permanent and unchangeable information. Once the system validates the iRoT, it moves to the uRoT, which enables developers to store sensitive information while benefiting from greater flexibility than the iRoT. Similarly, we offer life cycle management mechanisms to activate or deactivate readout protections (RDP), hide protections (HDP), and other features according to stages in the development process. For instance, debug authentication means developers can send a password through JTAG/SWD to re-open a device and deal with bugs while in the field.
These implementations are essential for companies to meet new security requirements, but are also often outside the scope of what most companies can or will handle. Beyond the expertise, it requires processes, audits, and machines that many just don’t have. For instance, the STM32G5 can come with unique IDs and certifiable keys to meet the latest attestation requirements. This is fundamental when implementing secure firmware installations, over-the-air updates, or root secure services (RSS), among other things. It also means that engineers don’t necessarily have to add a secure element to their bill of materials.
Isolation
Why is isolation essential to future-proof security?
Code isolation plays a big role in ensuring compliance with the latest regulations, such as the EU Cyber Resilience Act (CRA) or the US FDA cybersecurity guidance for medical devices, just to name two, which demand that companies ensure the integrity of their solutions. And while there are many different ways to achieve this, isolation of fundamental firmware, keys, or code is often a preferred method. Isolation is not new and has proven very effective. However, it used to be a costly method because it required a lot of memory and computing resources. However, today, this is a common practice on embedded systems, and the STM32G5 helps teams by making isolation less costly and more accessible.
Why TrustZone on the STM32G5 matters?
This is possible thanks to the TrustZone on the Cortex-M33. In essence, this feature allows developers to segregate code into two categories: trusted and non-trusted domains. In a nutshell, it sits between the root of trust (both iRoT and uRoT), where the Secure Boot lives, and the non-trusted domain, which holds the application that developers can easily flash or debug. It offers additional guarantees because a compromised application in the non-trusted domain cannot spill over into the trusted domain. As a result, it reduces the attack surface available and helps protect the most critical aspects of a system, which also means that it becomes easier to reset it since it only affects the non-trusted domain.
Why is key store aided by hardware essential for power supply?
M-CRPS requires several keys to be injected during manufacturing. We use these keys used for device authentication, software measurements, secure communication, secure boot, and firmware updates. Accordingly, they must be managed in a highly secure manner during the product’s lifetime (manufacturing, field use), or the damage could be catastrophic. The STM32G5 thus features a hardware key wrapping mechanism enabling secure key storage and Secure Crypto Engines, ensuring keys can not be disclosed during their use. They remain isolated and protected so the underlying systems can rely on them to establish trust and guarantee integrity.