Boosting Multi-Core Reachability Performance with Shared Hash Tables

This paper focuses on data structures for multi-core reachability, which is a key component in model checking algorithms and other verification methods. A cornerstone of an efficient solution is the storage of visited states. In related work, static partitioning of the state space was combined with thread-local storage and resulted in reasonable speedups, but left open whether improvements are possible. In this paper, we present a scaling solution for shared state storage which is based on a lockless hash table implementation. The solution is specifically designed for the cache architecture of modern CPUs. Because model checking algorithms impose loose requirements on the hash table operations, their design can be streamlined substantially compared to related work on lockless hash tables. Still, an implementation of the hash table presented here has dozens of sensitive performance parameters (bucket size, cache line size, data layout, probing sequence, etc.). We analyzed their impact and compared the resulting speedups with related tools. Our implementation outperforms two state-of-the-art multi-core model checkers (SPIN and DiVinE) by a substantial margin, while placing fewer constraints on the load balancing and search algorithms.Comment: preliminary repor

How Smart is your Android Smartphone?

Smart phones are ubiquitous today. These phones generally have access to sensitive personal information and, consequently, they are a prime target for attackers. A virus or worm that spreads over the network to cell phone users could be particularly damaging. Due to a rising demand for secure mobile phones, manufacturers have increased their emphasis on mobile security. In this project, we address some security issues relevant to the current Android smartphone framework. Specifically, we demonstrate an exploit that targets the Android telephony service. In addition, as a defense against the loss of personal information, we provide a means to encrypt data stored on the external media card. While smartphones remain vulnerable to a variety of security threats, this encryption provides an additional level of security