Abstract
Assurance of fulfillment of stakeholder's expectations on a target platform is termed as remote attestation. Without such an assurance, there is no way of knowing whether the policies of the remote owner will be enforced as expected. Existing approaches toward remote attestation work at different levels of the software stack and most of them only measures single entities (OS and/or application) on a remote platform. Several dynamic attestation techniques have been proposed that aim to measure the internal working of an application. In TCG-based attestations we use Platform Configuration Register (PCR) for storing and advocating the platform or application integrity to a remote party. Currently a single PCR is used to capture the behavior of one application or purpose. As there can be more than one applications running on a target system, we need to have mechanisms to remotely certify the internal behavior of multiple applications on a single system. In this paper we propose the idea of using a single PCR for multiple instances of a target application, while preserving the privacy of other application instances. Moreover, our technique also keeps the trusted status of each application intact. We change the working of the existing remote attestation techniques by enabling them to incorporate multiple instances of the entities (operating systems, programs etc.) that they measure. We also propose technique for measurement and verification of a single instance by its respective stakeholder while keeping the privacy of others. The mechanism proposed in this paper is applied on different attestation techniques that work at different levels of the software stack. We also provide a proof-of-concept implementation of the proposed technique and discuss the pros and cons of our approach.