Deian Stefan : 2012 Security Session

When termination of a program is observable by an adversary, confidential information may be leaked by terminating accordingly. While this termination covert channel has limited bandwidth for sequential programs, it is a more dangerous source of information leakage in concurrent settings. We address concurrent termination and timing channels by presenting an information-flow control system that mitigates and eliminates these channels while allowing termination and timing to depend on secret values. Intuitively, we leverage concurrency by placing such potentially sensitive actions in separate threads. While termination and timing of these threads may expose secret values, our system requires any thread observing these properties to raise its information-flow label accordingly, preventing leaks to lower-labeled contexts. We develop our approach in a Haskell library and demonstrate its applicability by implementing a web server that uses information-flow control to restrict untrusted web applications.

Deian Stefan is a second year Ph.D. student in the Computer Science, at Stanford University. His research interest are in computer security, with specific attention to language-based and library-based approaches to decentralized information flow control and secure computation. Prior to Stanford he obtained a B.E. and M.E. in Electrical Engineering at Cooper Union, where he focused on applying GPUs and FPGAs to speeding up cryptographic and cryptanalysis algorithms.