Remote Attestation for Embedded Systems

Large distributed systems, like Industrial Control Systems, should be able to verify that devices that are connected to trusted entities are real authorized network nodes running unmodified firmware. Remote attestation is a mechanism that can provide limited confidence of device identity and integrity. Remote attestation allows a remote verifier, e.g. a service provider, to verify integrity of the connecting system before providing a service. The current standard practice in remote attestation, defined by the Trusted Computing Group (TCG), is based on integrity measurements whose results are stored into an isolated trusted component called Trusted Platform Module (TPM) inside the system to be attested. The proof-of-concept scenario implementing similar functionality using an ARM processor secure environment is discussed. The implementation is done using ARM processor emulator which includes emulation for ARM TrustZone Trusted Execution Environment (TEE) providing isolated trusted component functionality. Challenges and security issues of the chosen approach are discussed.