Arm® TrustZone® is an embedded security technology that provides hardware-enforced separation of MCU features. Arm introduced this technology into Cortex®-M cores with the ARMv8M architecture. This isolation capability enables a protected environment by splitting the MCU capabilities into two regions. The secure world region contains trusted firmware and services, whereas the non-secure world contains all non-trusted firmware and services. The secure world is not entirely cut off from non-secure region and it can call the secure world when needed through non-secure callable functions, which is what makes TrustZone so unique. These functions provide defined access points into a secure world.