Flexible Mechanisms for Remote Attestation

Remote attestation consists of generating evidence of a system’s integrity via measurements and reporting the evidence to a remote party for appraisal in a form that can be trusted. The parties that exchange information must agree on formats and protocols. We assert there is a large variety of patterns of interactions among appraisers and attesters of interest. Therefore, it is important to standardize on flexible mechanisms for remote attestation. We make our case by describing scenarios that require the exchange of evidence among multiple parties using a variety of message passing patterns. We show cases in which changes in the order of evidence collection result in important differences to what can be inferred by an appraiser. We argue that adding the ability to negotiate the appropriate kind of attestation allows for remote attestations that better adapt to a dynamically changing environment. Finally, we suggest a language-based solution to taming the complexity of specifying and negotiating attestation procedures.