Luke St. Clair
Pennsylvania State University
USA

Joshua Schiffman
Pennsylvania State University
USA

Trent Jaeger
Pennsylvania State University
United States

Patrick McDaniel
Pennsylvania State University
United States

Integrity measurements provide a means by which distributed systems can assess the trustability of potentially compromised remote hosts. However, current measurement techniques simply assert the identity of software, but provide no indication of the ongoing status of the system or its data. As a result, a number of significant vulnerabilities can result if the system is not configured and managed carefully. To improve the management of a system’s integrity, we propose a Root of Trust Installation (ROTI) as a foundation for high integrity systems. A ROTI is a trusted system installer that also asserts the integrity of the trusted computing base software and data that it installs to enable straightforward, comprehensive integrity verification for a system. The ROTI addresses a historically limiting problem in integrity measurement: determining what constitutes a trusted
system state in any heterogeneous, evolving environment. Using the ROTI, a high integrity system state is defined by its installer, thus enabling a remote party to verify integrity guarantees that approximate classical integrity models (e.g., Biba). In this paper, we examine what is necessary to prove the integrity of the trusted computing base (sCore) of a distributed security architecture, called the SRM. We describe the design and implementation of our custom ROTI sCore installer and study the costs and effectiveness of binding system integrity to installation in the distributed SRM. This demonstration shows that strong integrity guarantees can be efficiently achieved in large, diverse environments with limited administrative overhead.

Keywords: integrity measurement, root of trust, trusted computing, distributed system security

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