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Distributed Graph Automata [article]

Fabian Reiter
2014 arXiv   pre-print
Inspired by distributed algorithms, we introduce a new class of finite graph automata that recognize precisely the graph languages definable in monadic second-order logic. For the cases of words and trees, it has been long known that the regular languages are precisely those definable in monadic second-order logic. In this regard, the automata proposed in the present work can be seen, to some extent, as a generalization of finite automata to graphs. Furthermore, we show that, unlike for finite
more » ... utomata on words and trees, the deterministic, nondeterministic and alternating variants of our automata form a strict hierarchy with respect to their expressive power. For the weaker variants, the emptiness problem is decidable.
arXiv:1404.6503v1 fatcat:oflqmcgf55gazpnnienzsdqy6u

Distributed Automata and Logic [article]

Fabian Reiter
2018 arXiv   pre-print
Distributed automata are finite-state machines that operate on finite directed graphs. Acting as synchronous distributed algorithms, they use their input graph as a network in which identical processors communicate for a possibly infinite number of synchronous rounds. For the local variant of those automata, where the number of rounds is bounded by a constant, Hella et al. (2012, 2015) have established a logical characterization in terms of basic modal logic. In this thesis, we provide similar
more » ... ogical characterizations for two more expressive classes of distributed automata. The first class extends local automata with a global acceptance condition and the ability to alternate between nondeterministic and parallel computations. We show that it is equivalent to monadic second-order logic on graphs. By restricting transitions to be nondeterministic or deterministic, we also obtain two strictly weaker variants for which the emptiness problem is decidable. Our second class transfers the standard notion of asynchronous algorithm to the setting of nonlocal distributed automata. The resulting machines are shown to be equivalent to a small fragment of least fixpoint logic, and more specifically, to a restricted variant of the modal μ-calculus that allows least fixpoints but forbids greatest fixpoints. Exploiting the connection with logic, we additionally prove that the expressive power of those asynchronous automata is independent of whether or not messages can be lost.
arXiv:1805.06238v1 fatcat:6cdcn5fkszae5c4qeqs5elhdga

Alternating Set Quantifiers in Modal Logic [article]

Fabian Reiter
2016 arXiv   pre-print
We establish the strictness of several set quantifier alternation hierarchies that are based on modal logic, evaluated on various classes of finite graphs. This extends to the modal setting a celebrated result of Matz, Schweikardt and Thomas (2002), which states that the analogous hierarchy of monadic second-order logic is strict. Thereby, the present paper settles a question raised by van Benthem (1983), revived by ten Cate (2006), and partially answered by Kuusisto (2008, 2015).
arXiv:1602.08971v1 fatcat:sum4d4tp5zhwvjsafg4oh2zfwm

A Classification of Weak Asynchronous Models of Distributed Computing [article]

Javier Esparza, Fabian Reiter
2020 arXiv   pre-print
ACM, 58(1):94-102, 2015. doi:10.1145/2678280. 13 Fabian Reiter. Asynchronous distributed automata: A characterization of the modal mu- fragment. In ICALP, volume 80 of LIPIcs, pages 100:1-100:14.  ...  URL: https://doi.org/10.1145/4221.4227, doi:10.1145/4221.4227. 5 Alejandro Cornejo and Fabian Kuhn. Deploying wireless networks with beeps.  ... 
arXiv:2007.03291v1 fatcat:asvs45ozlbdpvgwt55nahu4dpa

Understanding domain registration abuses

Scott E. Coull, Andrew M. White, Ting-Fang Yen, Fabian Monrose, Michael K. Reiter
2012 Computers & security  
The ability to monetize domain names through resale or serving ad content has contributed to the rise of questionable practices in acquiring them, including domain-name speculation, tasting, and front running. In this paper, we perform one of the first comprehensive studies of these domain registration practices. In order to characterize the prevalence of domain-name speculation, we derive rules describing "hot" topics from popular Google search queries and apply these rules to a dataset
more » ... ing all .com registrations for an eight-month period in 2008. We also study the extent of domain tasting throughout this time period and analyze the efficacy of ICANN policies intended to limit tasting activity. Finally, we automatically generate high-quality domain names related to current events in order to measure domain front running by registrars. The results of our experiments shed light on the methods and motivations behind these domain registration practices and in some cases underscore the difficulty in definitively measuring these questionable behaviors.
doi:10.1016/j.cose.2012.05.005 fatcat:wp4h7nat4bcclcp5l26pesmal4

Eine Neuedition von P.Berl. Cohen 8

Dieter Hagedorn, Fabian Reiter
2015 Archiv für Papyrusforschung und verwandte Gebiete  
einer Autopsie durch Fabian Reiter -wesentliche Fortschritte in der Entzifferung gemacht zu haben.  ... 
doi:10.1515/apf-2015-0032 fatcat:5dhkjuajdvhobaq6d5sschv6fi

Time-Scoped Searching of Encrypted Audit Logs [chapter]

Darren Davis, Fabian Monrose, Michael K. Reiter
2004 Lecture Notes in Computer Science  
In this paper we explore restricted delegation of searches on encrypted audit logs. We show how to limit the exposure of private information stored in the log during such a search and provide a technique to delegate searches on the log to an investigator. These delegated searches are limited to authorized keywords that pertain to specific time periods, and provide guarantees of completeness to the investigator. Moreover, we show that investigators can efficiently find all relevant records, and
more » ... an authenticate retrieved records without interacting with the owner of the log. In addition, we provide an empirical evaluation of our techniques using encrypted logs consisting of approximately 27, 000 records of IDS alerts collected over a span of a few months.
doi:10.1007/978-3-540-30191-2_41 fatcat:4xggyh7lynczvirkrhfcdya2x4

Perspective+detail

Tobias Schwarz, Fabian Hennecke, Felix Lauber, Harald Reiterer
2012 Proceedings of the International Working Conference on Advanced Visual Interfaces - AVI '12  
This paper describes the perspective+detail visualization concept, which extends the conventional overview+detail pattern by adding a perspective viewing area and a further, text-based area containing partial details. Known problems of such extensions are mitigated using a vertically curved display. Our concept aims to bridge both the geographical and the content gap between the two main display areas and to provide an improved overview. An experimental case study based on a typical traffic
more » ... rol room operator task provided first insights on our visualization. These initial findings revealed that perspective+detail assists users in fulfilling their tasks and keeping their orientation in the information space.
doi:10.1145/2254556.2254648 dblp:conf/avi/SchwarzHLR12 fatcat:ggnc7nn7hvcrdculug262qarci

Password hardening based on keystroke dynamics

Fabian Monrose, Michael K. Reiter, Susanne Wetzel
2002 International Journal of Information Security  
Reiter, S.  ...  We reiterate that the false positive curves in Fig. 4 are of little interest to us here (see Sect. 3.2). They do, however, show why we do not rely on keystroke patterns alone to authenticate users.  ... 
doi:10.1007/s102070100006 fatcat:7b3wnbavxfazzgilgg7ldb3wei

Asynchronous Distributed Automata: A Characterization of the Modal Mu-Fragment [article]

Fabian Reiter
2016 arXiv   pre-print
We establish the equivalence between a class of asynchronous distributed automata and a small fragment of least fixpoint logic, when restricted to finite directed graphs. More specifically, the logic we consider is (a variant of) the fragment of the modal μ-calculus that allows least fixpoints but forbids greatest fixpoints. The corresponding automaton model uses a network of identical finite-state machines that communicate in an asynchronous manner and whose state diagram must be acyclic
more » ... for self-loops. Exploiting the connection with logic, we also prove that the expressive power of those machines is independent of whether or not messages can be lost.
arXiv:1611.08554v1 fatcat:3bnnao7g2zfrbgurejrpyzxxue

Identifiers in Registers [chapter]

Benedikt Bollig, Patricia Bouyer, Fabian Reiter
2019 Green Chemistry and Sustainable Technology  
Motivated by this result, several variants of distributed automata were investigated by Kuusisto and Reiter in [14, 18] and [17] to establish similar connections with standard logics such as the modal  ... 
doi:10.1007/978-3-030-17127-8_7 dblp:conf/fossacs/BolligBR19 fatcat:sahjrqc6vvbolbarhj5bzerin4

Understanding Domain Registration Abuses [chapter]

Scott E. Coull, Andrew M. White, Ting-Fang Yen, Fabian Monrose, Michael K. Reiter
2010 IFIP Advances in Information and Communication Technology  
The ability to monetize domain names through resale or serving ad content has contributed to the rise of questionable practices in acquiring them, including domain-name speculation, tasting, and front running. In this paper, we perform one of the first comprehensive studies of these domain registration practices. In order to characterize the prevalence of domain-name speculation, we derive rules describing "hot" topics from popular Google search queries and apply these rules to a dataset
more » ... ing all .com registrations for an eight-month period in 2008. We also study the extent of domain tasting throughout this time period and analyze the efficacy of ICANN policies intended to limit tasting activity. Finally, we automatically generate high-quality domain names related to current events in order to measure domain front running by registrars. The results of our experiments shed light on the methods and motivations behind these domain registration practices and in some cases underscore the difficulty in definitively measuring these questionable behaviors.
doi:10.1007/978-3-642-15257-3_7 fatcat:7cqqjl3e4jgatn5a64mwfhty5q

Browser Fingerprinting from Coarse Traffic Summaries: Techniques and Implications [chapter]

Ting-Fang Yen, Xin Huang, Fabian Monrose, Michael K. Reiter
2009 Lecture Notes in Computer Science  
We demonstrate that the browser implementation used at a host can be passively identified with significant precision and recall, using only coarse summaries of web traffic to and from that host. Our techniques utilize connection records containing only the source and destination addresses and ports, packet and byte counts, and the start and end times of each connection. We additionally provide two applications of browser identification. First, we show how to extend a network intrusion detection
more » ... system to detect a broader range of malware. Second, we demonstrate the consequences of web browser identification to the deanonymization of web sites in flow records that have been anonymized.
doi:10.1007/978-3-642-02918-9_10 fatcat:w3uuv4f3bzhlnkbd34vtggl3fy

Privacy-preserving global customization

Robert M. Arlein, Ben Jai, Markus Jakobsson, Fabian Monrose, Michael K. Reiter
2000 Proceedings of the 2nd ACM conference on Electronic commerce - EC '00  
We present an architecture for global customization of web content, by w h i c h a w eb site can customize content for each visitor based on the activities undertaken by the same user on other, unrelated sites. Our architecture distinguishes itself in the privacy mechanisms it provides: each u s e r c o n trols what information a merchant can learn about her activities at other merchants, and each merchant controls to what other merchants the information it contributes is revealed. To a c hieve
more » ... t h i s w e i n troduce novel data protection mechanisms for merchants and users. We further describe aspects of a prototype implementation of our architecture.
doi:10.1145/352871.352891 dblp:conf/sigecom/ArleinJJMR00 fatcat:xbfy7u5sfvgqfbdzrofbplif6y

The security of modern password expiration

Yinqian Zhang, Fabian Monrose, Michael K. Reiter
2010 Proceedings of the 17th ACM conference on Computer and communications security - CCS '10  
This paper presents the first large-scale study of the success of password expiration in meeting its intended purpose, namely revoking access to an account by an attacker who has captured the account's password. Using a dataset of over 7700 accounts, we assess the extent to which passwords that users choose to replace expired ones pose an obstacle to the attacker's continued access. We develop a framework by which an attacker can search for a user's new password from an old one, and design an
more » ... ficient algorithm to build an approximately optimal search strategy. We then use this strategy to measure the difficulty of breaking newly chosen passwords from old ones. We believe our study calls into question the merit of continuing the practice of password expiration.
doi:10.1145/1866307.1866328 dblp:conf/ccs/ZhangMR10 fatcat:ixnjcbhazvhunp5dfstm7ipt4y
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