Help Me Help You: Using Trustworthy Host-Based Information in the Network (CMU-CyLab-09-016)

As hardware support for improved endhost security becomes ubiquitous, it is important to consider how network security and performance can benefit from these improvements. If endhosts (or at least portions of each endhost) can be trusted, then network infrastructure no longer needs to arduously and imprecisely reconstruct data already known by the endhosts. Through the design of a general-purpose architecture we call Assayer, we explore the issues in providing trusted host-based data, including the balance between useful information and user privacy, and the tradeoffs between security and efficiency. We also evaluate the usefulness of such information in three case studies. To gain insight into the performance we could expect from such a system, we implement and evaluate a basic Assayer prototype. Our prototype requires fewer than 1,000 lines of code on the endhost. Endhosts can annotate their outbound traffic in a few microseconds, and these annotations can be checked efficiently; even packet-level annotations on a gigabit link can be checked with a loss in throughput of only 3.7-18.3%.