  Remote Attestation (RA) enables the integrity and authenticity of
applications in Trusted Execution Environment (TEE) to be verified. Existing
TEE RA designs employ a centralized trust model where they rely on a single
provisioned secret key and a centralized verifier to establish trust for remote
parties. This model is however brittle and can be untrusted under advanced
attacks nowadays. Besides, most designs only provide fixed functionalities once
deployed, making them hard to adapt to different needs on availability, Quality
of Service (QoS), etc.
  Therefore, we propose JANUS, an open and resilient TEE RA scheme. To
decentralize trust, we, on one hand, introduce Physically Unclonable Function
(PUF) as an intrinsic root of trust (RoT) in TEE to provide additional
measurements and cryptographic enhancements. On the other hand, we use
blockchain and smart contract to realize decentralized verification and result
audit. Furthermore, we design an automated turnout mechanism that allows JANUS
to remain resilient and offer flexible RA services under various situations. We
provide a UC-based security proof and demonstrate the scalability and
generality of JANUS by implementing an open-sourced prototype.
