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Creators/Authors contains: "Oakley, Lisa"

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  1. Programmatically generating tight differential privacy (DP) bounds is a hard problem. Two core challenges are (1) finding expressive, compact, and efficient encodings of the distributions of DP algorithms, and (2) state space explosion stemming from the multiple quantifiers and relational properties of the DP definition. We address the first challenge by developing a method for tight privacy and accuracy bound synthesis using weighted model counting on binary decision diagrams, a state of the art technique from the artificial intelligence and automated reasoning communities for exactly computing probability distributions. We address the second challenge by developing a framework for leveraging inherent symmetries in DP algorithms. Our solution benefits from ongoing research in probabilistic programming languages, allowing us to succinctly and expressively represent different DP algorithms with approachable language syntax that can be used by non-experts. We provide a detailed case study of our solution on the binary randomized response algorithm. We also evaluate an implementation of our solution using the Dice probabilistic programming language for the randomized response and truncated geometric above threshold algorithms. We compare to prior work on exact DP verification using Markov chain probabilistic model checking and the decision procedure DiPC. Very few existing works consider mechanized analysis of accuracy guarantees for DP algorithms. We additionally provide a detailed analysis using our technique for finding tight accuracy bounds for DP algorithms 
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  2. As machine learning systems become more pervasive in safety-critical tasks, it is important to carefully analyze their robustness against attack. Our work focuses on developing an extensible framework for verifying adversarial robustness in machine learning systems over time, leveraging existing methods from probabilistic model checking and optimization. We present preliminary progress and consider future directions for verifying several key properties against sophisticated, dynamic attackers. 
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  3. As machine learning systems become more pervasive in safety-critical tasks, it is important to carefully analyze their robustness against attack. Our work focuses on developing an extensible framework for verifying adversarial robustness in machine learning systems over time, leveraging existing methods from probabilistic model checking and optimization. We present preliminary progress and consider future directions for verifying several key properties against sophisticated, dynamic attackers. 
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  4. A rise in Advanced Persistent Threats (APTs) has introduced a need for robustness against long-running, stealthy attacks which circumvent existing cryptographic security guarantees. FlipIt is a security game that models attacker-defender interactions in advanced scenarios such as APTs. Previous work analyzed extensively non-adaptive strategies in FlipIt, but adaptive strategies rise naturally in practical interactions as players receive feedback during the game. We model the FlipIt game as a Markov Decision Process and introduce QFlip, an adaptive strategy for FlipIt based on temporal difference reinforcement learning. We prove theoretical results on the convergence of our new strategy against an opponent playing with a Periodic strategy. We con firm our analysis experimentally by extensive evaluation of QFlip against speci fic opponents. QFlip converges to the optimal adaptive strategy for Peri- odic and Exponential opponents using associated state spaces. Finally, we introduce a generalized QFlip strategy with composite state space that outperforms a Greedy strategy for several distributions including Periodic and Uniform, without prior knowledge of the opponent's strategy. We also release an OpenAI Gym environment for FlipIt to facilitate future research. 
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