TrustZone-M

ARMv7-M cores, such as the Cortex-M0+ and Cortex-M4 microcontrollers, have dominated the embedded market for decades and are still the most popular choice for many embedded system designs. Although there have been a number of changes and additions, the new Cortex-M23 and Cortex-M33 cores, as well as the newer M35P and M55, have inherited and expanded many of the successful features of the Cortex-M0, Cortex-M4, and Cortex-M7 microcontrollers.

In a typical TrustZone use case, multiple actors may be involved in the distinct phases of software development. The owner of a device may provide a base system, already equipped with all the software authorized to run in the secure world. This would still leave the possibility for a system integrator to customize the non-secure part but with a restricted view of the system, which depends on the configuration of the resources allowed by the secure domain. The system integrator in this case receives a system that is partially locked...