1,720,963 research outputs found
Functional Credentials
No full textAbstractA functional credential allows a user to anonymously prove possession of a set of attributes that fulfills a certain policy. The policies are arbitrary polynomially computable predicates that are evaluated over arbitrary attributes. The key feature of this primitive is the delegation of verification to third parties, called designated verifiers. The delegation protects theprivacy of the policy: A designated verifier can verify that a user satisfies a certain policy without learning anything about the policy itself. We illustrate the usefulness of this property in different applications, including outsourced databases with access control. We present a new framework to construct functional credentials that does not require (non-interactive) zero-knowledge proofs. This is important in settings where the statements are complex and thus the resulting zero-knowledge proofs are not efficient. Our construction is based on any predicate encryption scheme and the security relies on standard assumptions. A complexity analysis and an experimental evaluation confirm the practicality of our approach.</jats:p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
My Genome Belongs to Me: Controlling Third Party Computation on Genomic Data
No full textAn individual’s genetic information is pos- sibly the most valuable personal information. While knowledge of a person’s DNA sequence can facilitate the diagnosis of several heritable diseases and allow per- sonalized treatment, its exposure comes with significant threats to the patient’s privacy. Currently known so- lutions for privacy-respecting computation require the owner of the DNA to either be heavily involved in the execution of a cryptographic protocol or to completely outsource the access control to a third party. This mo- tivates the demand for cryptographic protocols which enable computation over encrypted genomic data while keeping the owner of the genome in full control. We envi- sion a scenario where data owners can exercise arbitrary and dynamic access policies, depending on the intended use of the analysis results and on the credentials of who is conducting the analysis. At the same time, data own- ers are not required to maintain a local copy of their entire genetic data and do not need to exhaust their computational resources in an expensive cryptographic protocol.
In this work, we present METIS, a system that as- sists the computation over encrypted data stored in the cloud while leaving the decision on admissible computa- tions to the data owner. It is based on garbled circuits and supports any polynomially-computable function. A critical feature of our system is that the data owner is free from computational overload and her communica- tion complexity is independent of the size of the input data and only linear in the size of the circuit’s output. We demonstrate the practicality of our approach with an implementation and an evaluation of several functions over real datasets
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Kryptowährungen im Spannungsfeld zwischen Recht und IT-Sicherheit
Full text linkBitcoin and other cryptocurrencies are digital means of payment. They primarily differ from traditional fiat money by not requiring a central authority to issue new units of the currency or process payments. Cryptocurrencies achieve this decentralization by using a ledger of transactions. Participants in a network maintain the ledger and decide which transactions to add to it. The ledger is immutable: transactions cannot be removed anymore once added. Besides, cryptocurrency transactions differ from classical bank transfers in that cryptocurrency users can generate new pseudonyms for each transaction and are not restricted to account numbers that banks can directly link to the account holders. In addition, transactions can contain arbitrary data beyond payment information. These properties of cryptocurrencies raise issues within the conflicting tension between law and IT security. This work deals with three of these issues and shows that they are not solvable solely by legal or technical means.
First, network participants face criminal liability if illegal content is embedded into the ledger. In the case of personal data on the ledger, the participants might be obliged to erase it to comply with data protection regulations, namely the right to be forgotten. We propose a protocol that allows removing content from the ledger. Our protocol does not require any additional trust assumptions as it employs the exact mechanism used by the participants to maintain the ledger. By allowing the participants to break the immutability property, they can more effectively comply with the law.
Second, cryptocurrencies are the primary means of payment on the dark web. Thus, law enforcement commonly analyses cryptocurrency transactions. These analyses include tracing payment flows and linking multiple pseudonyms used in transactions that belong to the same person. The ultimate goal of these analyses is to identify the persons behind the pseudonyms. Cryptocurrency analyses typically rely on assumptions. These assumptions are often not questioned by law enforcement. However, their reliability is crucial to justify any subsequent investigation against an identified person. We extracted assumptions from scientific papers doing such analyses and classified them. In addition, we argue the reliability of each class of assumptions and introduce criteria to consider when arguing reliability on a case-by-case basis. Law enforcement, expert witnesses, and legal decision-makers can use our taxonomy and criteria to address the reliability of findings obtained from cryptocurrency analyses.
Third, although envisioned as digital cash, Bitcoin does not achieve the level of anonymity afforded by cash. As the ledger is public, everyone can trace payment flows and link multiple pseudonyms that belong to the same person. Mixing protocols emerged as a way to improve anonymity in Bitcoin. The basic idea of mixing is to combine coins of multiple users to harden payment flow analyses and pseudonym linkage. We analyzed the built-in mixing of the cryptocurrency Dash, which works similarly to the mixing protocols run on top of Bitcoin. We found two anonymity issues. First, users spent mixed and unmixed coins together, thereby lifting the anonymity gained from mixing. Second, as mixing in Dash requires coins with a fixed value, the mixed coins typically need to be combined after mixing to pay a specific amount. This combination of mixed coins allows intersecting each coin’s anonymity set, which might also lift anonymity gains from mixing. To prevent the need to combine coins after mixing, we propose a mixing algorithm that does not require coins with fixed values. Furthermore, we provide insights that the found anonymity issues could also be present in Bitcoin.Bitcoin und andere Kryptowährungen sind digitale Zahlungsmittel. Sie unterscheiden sich von traditionellem Fiatgeld hauptsächlich dadurch, dass sie keine zentrale Autorität benötigen um neue Einheiten der Währung zu erzeugen oder Zahlungen abzuwickeln. Kryptowährungen erreichen diese Dezentralisierung durch die Verwendung eines Hauptbuchs für Transaktionen. Die Teilnehmenden eines Netzwerks führen das Hauptbuch und entscheiden, welche Transaktionen dem Hauptbuch hinzugefügt werden sollen. Das Hauptbuch ist unveränderlich: Einmal hinzugefügte Transaktionen können nicht mehr entfernt werden. Außerdem unterscheiden sich Kryptowährungstransaktionen von klassischen Banküberweisungen darin, dass kryptowährungsnutzende Personen für jede Transaktion neue Pseudonyme erstellen können und nicht auf Kontonummern beschränkt sind, die Banken direkt mit den Kontoinhabenden verknüpfen können. Darüber hinaus können Transaktionen neben den Zahlungsinformationen auch beliebige Daten enthalten. Diese Eigenschaften von Kryptowährungen werfen Fragen im Spannungsfeld zwischen Recht und IT-Sicherheit auf. Die vorliegende Arbeit befasst sich mit drei dieser Fragen und zeigt, dass sie nicht allein mit rechtlichen oder technischen Mitteln gelöst werden können.
Erstens könnten die Netzwerkteilnehmenden strafrechtlich belangt werden, wenn illegale Inhalte in das Hauptbuch eingefügt werden. Im Falle personenbezogener Daten im Hauptbuch könnten die Teilnehmenden verpflichtet sein, diese zu löschen, um Datenschutzbestimmungen einzuhalten, insbesondere das Recht auf Vergessenwerden. Wir schlagen ein Protokoll vor, das die Entfernung von Inhalten aus dem Hauptbuch ermöglicht. Unser Protokoll erfordert keine zusätzlichen Vertrauensannahmen, da es genau den Mechanismus nutzt, der von den Teilnehmenden zur Verwaltung des Hauptbuchs verwendet wird. Indem es den Teilnehmenden erlaubt, die Eigenschaft der Unveränderlichkeit zu brechen, können sie die Gesetze effektiver einhalten.
Zweitens sind Kryptowährungen das wichtigste Zahlungsmittel im Dark Web. Daher analysieren Strafverfolgungsbehörden in der Regel Kryptowährungstransaktionen. Diese Analysen umfassen die Nachverfolgung von Zahlungsströmen und die Verknüpfung mehrerer Pseudonyme, die in Transaktionen verwendet werden und zu ein und derselben Person gehören. Das ultimative Ziel dieser Analysen ist es, die Personen hinter den Pseudonymen zu identifizieren. Kryptowährungsanalysen beruhen in der Regel auf Annahmen. Diese Annahmen werden von den Strafverfolgungsbehörden oft nicht hinterfragt. Ihre Zuverlässigkeit ist jedoch von entscheidender Bedeutung, um spätere Ermittlungen gegen eine identifizierte Person zu rechtfertigen. Wir haben Annahmen aus wissenschaftlichen Arbeiten extrahiert, die solche Analysen durchführen, und sie klassifiziert. Darüber hinaus argumentieren wir die Zuverlässigkeit jeder Klasse von Annahmen und stellen Kriterien vor, die bei der Argumen- tation der Zuverlässigkeit im Einzelfall zu berücksichtigen sind. Strafverfolgungsbehörden, Sachverständige und juristische Entscheidungstragende können unsere Taxonomie und die Kriterien nutzen, um die Zuverlässigkeit der aus Kryptowährungsanalysen gewonnenen Erkenntnisse zu beurteilen.
Drittens erreicht Bitcoin, obwohl es als digitales Bargeld gedacht war, nicht den Grad an Anonymität, den Bargeld bietet. Da das Hauptbuch öffentlich ist, können alle die Zahlungsströme nachverfolgen und mehrere Pseudonyme, die zu ein und derselben Person gehören, miteinander verknüpfen. Misch-Protokolle sind als eine Möglichkeit zur Verbesserung der Anonymität in Bitcoin entstanden. Die Grundidee des Mischens besteht darin, Münzen mehrerer Nutzenden zu kombinieren, um die Analyse von Zahlungsströmen und die Verknüpfung von Pseudonymen zu erschweren. Wir analysierten das eingebaute Mischen der Kryptowährung Dash, das ähnlich funktioniert wie die Misch-Protokolle, die auf Bitcoin laufen. Wir fanden zwei Anonymitätsprobleme. Erstens gaben Nutzende gemischte und nicht gemischte Münzen zusammen aus, wodurch die durch das Mischen gewonnene Anonymität aufgehoben wurde. Zweitens erfordert das Mischen in Dash Münzen mit einem festen Wert, so dass die gemischten Münzen in der Regel nach dem Mischen kombiniert werden müssen, um einen bestimmten Betrag zu zahlen. Diese Kombination gemischter Münzen ermöglicht es, die Anonymitätsmengen der einzelnen Münzen zu schneiden, was die Anonymitätsgewinne durch das Mischen ebenfalls aufheben könnte. Um zu verhindern, dass Münzen nach dem Mischen kombiniert werden müssen, schlagen wir einen Misch-Algorithmus vor, der keine Münzen mit festen Werten erfordert. Außerdem zeigen wir, dass die gefundenen Anonymitätsprobleme auch bei Bitcoin auftreten könnten
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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