Dynamic Measurement and Protected Execution: Model and Analysis

Useful security properties arise from sealing data to specific units of code. Modern processors featuring Intel’s TXT and AMD’s SVM achieve this by a process of measured and protected execution. Only code which has the correct measurement can access the data, and this code runs in an environment protected from observation and interference. We present a modelling language with primitives for protected execution, along with its semantics. We characterise an attacker who has access to all the capabilities of the hardware. In order to achieve automatic analysis of systems using protected execution without attempting to search an infinite state space, we define transformations that reduce the number of times the attacker needs to use protected execution to a pre-determined bound. Given reasonable assumptions we prove the soundness of the transformation: no secrecy attacks are lost by applying it. We then describe using the StatVerif extensions to ProVerif to model the bounded invocations of protected execution. We show the analysis of realistic systems, for which we provide case studies.