Stylometric authorship attribution aims to identify an anonymous or disputed document’s author by examining its writing style. The development of powerful machine learning based stylometric authorship attribution methods presents a serious privacy threat for individuals such as journalists and activists who wish to publish anonymously. Researchers have proposed several authorship obfuscation approaches that try to make appropriate changes (e.g. word/phrase replacements) to evade attribution while preserving semantics. Unfortunately, existing authorship obfuscation approaches are lacking because they either require some manual effort, require significant training data, or do not work for long documents. To address these limitations, we propose a genetic algorithm based random search framework called Mutant-X which can automatically obfuscate text to successfully evade attribution while keeping the semantics of the obfuscated text similar to the original text. Specifically, Mutant-X sequentially makes changes in the text using mutation and crossover techniques while being guided by a fitness function that takes into account both attribution probability and semantic relevance. While Mutant-X requires black-box knowledge of the adversary’s classifier, it does not require any additional training data and also works on documents of any length. We evaluate Mutant-X against a variety of authorship attribution methods on two different text corpora. Our results show that Mutant-X can decrease the accuracy of state-of-the-art authorship attribution methods by as much as 64% while preserving the semantics much better than existing automated authorship obfuscation approaches. While Mutant-X advances the state-of-the-art in automated authorship obfuscation, we find that it does not generalize to a stronger threat model where the adversary uses a different attribution classifier than what Mutant-X assumes. Our findings warrant the need for future research to improve the generalizability (or transferability) of automated authorship obfuscation approaches.
Gerry Wan, Aaron Johnson, Ryan Wails, Sameer Wagh and Prateek Mittal
The popularity of Tor has made it an attractive target for a variety of deanonymization and fingerprinting attacks. Location-based path selection algorithms have been proposed as a countermeasure to defend against such attacks. However, adversaries can exploit the location-awareness of these algorithms by strategically placing relays in locations that increase their chances of being selected as a client’s guard. Being chosen as a guard facilitates website fingerprinting and traffic correlation attacks over extended time periods. In this work, we rigorously define and analyze the guard placement attack. We present novel guard placement attacks and show that three state-of-the-art path selection algorithms—Counter-RAPTOR, DeNASA, and LASTor—are vulnerable to these attacks, overcoming defenses considered by all three systems. For instance, in one attack, we show that an adversary contributing only 0.216% of Tor’s total bandwidth can attain an average selection probability of 18.22%, 84× higher than what it would be under Tor currently. Our findings indicate that existing location-based path selection algorithms allow guards to achieve disproportionately high selection probabilities relative to the cost required to run the guard. Finally, we propose and evaluate a generic defense mechanism that provably defends any path selection algorithm against guard placement attacks. We run our defense mechanism on each of the three path selection algorithms, and find that our mechanism significantly enhances the security of these algorithms against guard placement attacks with only minimal impact to the goals or performance of the original algorithms.
Jeremy Martin, Douglas Alpuche, Kristina Bodeman, Lamont Brown, Ellis Fenske, Lucas Foppe, Travis Mayberry, Erik Rye, Brandon Sipes and Sam Teplov
We investigate Apple’s Bluetooth Low Energy (BLE) Continuity protocol, designed to support interoperability and communication between iOS and macOS devices, and show that the price for this seamless experience is leakage of identifying information and behavioral data to passive adversaries. First, we reverse engineer numerous Continuity protocol message types and identify data fields that are transmitted unencrypted. We show that Continuity messages are broadcast over BLE in response to actions such as locking and unlocking a device’s screen, copying and pasting information, making and accepting phone calls, and tapping the screen while it is unlocked. Laboratory experiments reveal a significant flaw in the most recent versions of macOS that defeats BLE Media Access Control (MAC) address randomization entirely by causing the public MAC address to be broadcast. We demonstrate that the format and content of Continuity messages can be used to fingerprint the type and Operating System (OS) version of a device, as well as behaviorally profile users. Finally, we show that predictable sequence numbers in these frames can allow an adversary to track Apple devices across space and time, defeating existing anti-tracking techniques such as MAC address randomization.
The tools of multi-directional machining, having appeared in the recent years, have revolutionised turning operations. The chip removal of high feed roughing and finishing inserts is so specialised, that new formulas have to be introduced instead of those used so far. In this paper, the result of tests carried out up till now will be summarised; furthermore, a proposal will be made on the description, analysis and calculation of force demand of multi-directional inserts as well as the roughness of the surface being prepared during machining.
Homemaking as a concept is fundamental for all, being a part of life. The foundation of this idea is a key momentum in everyday life. With the growth of a city’s population, the demand for increased of living space and buildings will increase too. In a city, green spaces are a matter of high importance regarding their positive impact. Keeping these we give a further meaning to creating living spaces. In the process we concentrate on unused spaces.
In this article, we study the interior-point algorithm for solving linear complementarity problems, published by Xiaouje Ma, Hongwei Liu, Jianke Zhang and Weijie Cong from the implementation point of view. The algorithm was implemented in C++ programming language, thus supporting the effectiveness of the method. Despite the fact that the theoretical results refer only to the monotone linear complementarity problem, practical testing showed that the algorithm also works well in more general cases.
There are several technical inventors in Hungary who unfortunately have been forgotten or are not commemorated sufficiently. One of such Hungarian is Manfréd Weiss. In our research we examine his life and work, a life devoted to our technological development. Moreover, beyond his life, we also explore the famous inventor-engineer’s technical achievements and their impacts today. We also study the characteristics of the era in which he lived, in order to better understand the work and context of the inventor better.
I would like to emphasise that during our exploration, we realised the importance of this choice of topic: It is the duty of the later generations to explore and learn the work of their predecessors, and to spread and publish the conclusions as widely as possible.
Annabella Sánduly, Anett Tóth and Barnabás-Attila Lőrincz
Steel Eurocodes have an important role in the correct and adequate design of steel structures. Most of the programs, which are used for the static analysis of these structures take into consideration the information offered by the Eurocodes, thus giving the opportunity to entrust them with the task of solving those problems which are not clear and easily understandable for the user. As will be proven in this article, Eurocode 3 in some cases does not offer proper, clear explanations regarding some decisions. The main criticism for the whole Eurocode package is that the user might not see clearly the connection between the scattered parts of the final solution.
This paper presents the application of two model-based predictive control (MPC) algorithms on the cooling system of an office building. The two strategies discussed are a simple MPC, and an adaptive MPC algorithm connected to a model predictor. The cooling method used represents the air-conditioning unit of an HVAC system. The temperature of the building’s three rooms is controlled with fan coil units, based on the reference temperature and with different constraints applied. Furthermore, the building model is affected by dynamically changing interior and exterior heat sources, which we introduced into the controller as disturbances.
In many fields of industry frequency inverter drive is used to generate rotation when, due to a given technology or production process, modifying the speed of the engine is necessary. In this article we introduce a model built by us, through which we present the frequency inverter drive’s principles of utilization from different fields of industry and by using industrial automation devices. Through this model one can be familiarized with the 4 methods created by us that can be controlled through a complex yet easy to understand and user-friendly HMI