3.6.1 Introduction

The conversion of generic platforms into trusted computing platforms has been largely focused on open systems, such as the personal computing and server environments. Moreover, the majority of today's TPM implementations are chip-based, such as Intel's TPM-chip implementation, constructed as part of the LaGrande project (see Section 3.5), or the TPM chip manufactured by Infineon as part of their TPM professional package.

The necessity, however, for equivalent trusted computing functionality in embedded systems, such as smart phones and PDAs, has also become apparent ^[27] and these issues are being tackled within the TCG, particularly within the mobile phone working group. ARM TrustZone Technology focuses on the security of embedded systems rather than open platforms such as PCs and servers, where power consumption, performance and area are all issues that must be taken into account when implementing security mechanisms. ARM TrustZone is also illustrative of the key enabling technologies being developed so that software instantiations of TPMs may be deployed.

We briefly examine ARM's TrustZone technology, ^[4] which offers a safe execution environment or secure world for security critical functions, through the extension of an ARM CPU. By this means, security critical functions, for example, TPM functions, can be securely implemented and reliably protected from non-secure code running in the non-secure world on the platform ^[28].

ARM software technology is focused on enabling the TrustZone hardware, and providing a common environment for development of higher-level security services (such as TPMs) across...