Trusted execution environments (TEEs) protect sensitive code and data on computing platforms, even when the primary operating system is compromised. Once a technical curiosity, TEEs have rapidly become a key component in securing numerous systems from cloud servers to constrained devices. Today, TEEs have been deployed on billions of devices for protecting financial payments, personal files, copyrighted media content, and many others. Despite this, TEEs remain poorly understood due to their complexity and diversity. This book addresses this gap, providing a comprehensive treatment of different TEE technologies, their features, benefits, and shortcomings.A holistic view of secure and trusted execution is taken, examining smart cards and CPU protection rings before discussing modern TEEs, such as Intel SGX and ARM TrustZone. A wide range of paradigms for building secure and trusted execution environments are explored, from dedicated security chips to system-on-chip extensions and virtualisation technologies. The relevant industry standards and specifications are covered in detail, including how TEEs are evaluated and certified in practice with respect to security. Several case studies are presented showing how TEEs are used in some common security mechanisms, such as secure boot sequences, biometric authentication, and file-based encryption. This book also discusses present challenges in the field, covering potential attack vectors against TEEs and concerns relating to fragmentation, interoperability, and transparency. Lastly, a selection of future directions are examined that may be used by the trusted execution environments of tomorrow.This book is particularly targeted at practitioners and researchers in cyber security, such as penetration testers, security engineers, and security analysts. Additionally, this book serves as a valuable resource for university students, both postgraduate and advanced undergraduates, and professors in computer science and electrical engineering.
