ARM TrustZone and Secure Operating Systems

Abstract

This chapter covers ARM TrustZone technology and secure operating systems. It first describes the ARM TrustZone technology as a security extension in ARMv7 and its evolution to ARMv8 for security computing. It explains both hardware and software architectures to meet the needs for security. It describes the secure world and normal world, interactions, and switching between the two worlds. It explains the fundamental problem in secure systems, from booting time to establishing a chain of trusts in both hardware and software. It points out example systems based on TrustZone and research activities in this area. In line with this book’s presentation style, it uses example programs to show the implementation of a secure world and a normal world. The secure world comprises a secure monitor at EL3, which provides service functions at secure EL1. The normal world comprise processes at non-secure EL1, which use SMC to access service functions in the secure world, and switching between the two different worlds.