Oracle-based checking of untrusted software

Offline Integrity Checking of Untrusted Storage

We extend the offline memory correctness checking scheme presented by Blum et. al [BEG91] to develop an offline checker that can detect attacks by active adversaries. We introduce the concept of incremental multiset hashes, and detail one example: MSet-XOR MAC, which uses a secret key, and is efficient as updating the hash costs a few hash and XOR operations. Using multiset hashes as our underl...

Securing Untrusted and Malicious Software

Cache-based Model Checking of Networked Software

Many applications are concurrent and communicate over a network. The non-determinism in the thread and communication schedules makes it desirable to model check such systems. However, a simple state space exploration scheme is not applicable, as backtracking results in repeated communication operations. A cache-based approach solves this problem by hiding redundant communication operations from

JAMUS: Java Accommodation of Mobile Untrusted Software

Security is a major issue for mobile components that roam the Internet. When downloading a software component from the Internet, it is often impossible to decide in advance if this piece of code should be considered as safe or potentially dangerous for the local system. A malicious – or simply buggy – component might put the whole system in jeopardy, as it might destroy crucial data files, or c...

Oracle Circuits for Branching-Time Model Checking

A special class of oracle circuits with tree-vector form is introduced. It is shown that they can be evaluated in deterministic polynomial-time with a polylog number of adaptive queries to an NP oracle. This framework allows us to evaluate the precise computational complexity of model checking for some branching-time logics where it was known that the problem is NP-hard and coNP-hard.