A minimalist approach to Remote Attestation

Embedded computing devices increasingly permeate many aspects of modern life: from medical to automotive, from building and factory automation to weapons, from critical infrastructures to home entertainment. Despite their specialized nature as well as limited resources and connectivity, these devices are now becoming an increasingly popular and attractive target for attacks, especially, malware infections. A number of approaches have been suggested to detect and/or mitigate such attacks. They vary greatly in terms of application generality and underlying assumptions. However, one common theme is the need for Remote Attestation, a distinct security service that allows a trusted party (verifier) to check the internal state of a remote untrusted embedded device (prover). Many prior methods assume some form of trusted hardware on the prover, which is not a good option for small and low-end embedded devices. To this end, we investigate the feasibility of Remote Attestation without trusted hardware. This paper provides a systematic treatment of Remote Attestation, starting with a precise definition of the desired service and proceeding to its systematic deconstruction into necessary and sufficient properties. Next, these are mapped into a minimal collection of hardware and software components that result in secure Remote Attestation. One distinguishing feature of this line of research is the need to prove (or, at least argue for) architectural minimality - an aspect rarely encountered in security research. This work also provides a promising platform for attaining more advanced security services and guarantees.