1,720,958 research outputs found
Relating space and time in cryptography
Get PDFThis thesis studies the interplay between space and time in cryptography. It explores trade-offs between these two resources for honest parties and shows how fine-grained constraints on an adversary's capabilities can unlock new cryptographic functionalities. Adopting this perspective, we present results in four subfields of cryptography: 2PC: We prove tight lower bounds on the cost of oblivious transfer protocols, a central primitive for two-party computation, revealing a fundamental trade-off between communication and public-key operations. SNARG: We construct designated-verifier SNARGs with very short proofs, highlighting a novel trade-off between proof size and verifier efficiency. Incompressible Encryption: We construct a new incompressible encryption scheme. Incompressible encryption remains secure even after key exposure, assuming adversaries had limited space when the ciphertext was transmitted. This offers a lightweight alternative to forward secrecy for long messages. Space-Hard Functions: We define and construct verifiable space-hard functions and space-lock puzzles, space-based analogues of verifiable delay functions and time-lock puzzles. These enable new applications such as deniable proofs and leverage space limitations of the adversary. Together, these results demonstrate how a careful study of space-time trade-offs yields both foundational insights and practical cryptographic tools.Diese Arbeit untersucht das Zusammenspiel von Raum und Zeit in der Kryptographie. Sie analysiert Kompromisse zwischen diesen Ressourcen für ehrliche Parteien und zeigt, wie gezielte Beschränkungen der Fähigkeiten eines Angreifers neue Möglichkeiten eröffnen. Aus dieser Sicht liefern wir Beiträge in vier Bereichen: 2PC: Wir beweisen untere Schranken für die Kosten von Oblivious-Transfer-Protokollen, einem zentralen Primitive für Zwei-Parteien-Berechnung, und zeigen einen grundlegenden Trade-off zwischen Kommunikation und Public-Key-Operationen. SNARG: Wir konstruieren Designated-Verifier-SNARGs mit sehr kurzen Beweisen und demonstrieren einen neuen Trade-off zwischen Beweisgröße und Verifizierer-Effizienz. Inkomprimierbare Verschlüsselung: Wir stellen ein neues Schema vor, das auch nach Schlüsselkompromittierung sicher bleibt, solange der Angreifer beim Empfang nur begrenzten Raum hatte. Es bietet eine leichte Alternative zur Vorwärtsgeheimhaltung bei langen Nachrichten. Raum-Harte Funktionen: Wir definieren und konstruieren die ersten verifizierbaren raum-harte Funktionen und Raum-Lock-Rätsel, raumbasierte Gegenstücke zu Time-Lock-Rätseln. Diese ermöglichen neue Anwendungen wie ableugbare Beweise und nutzen Raumbeschränkung des Angreifers. Diese Resultate zeigen, dass eine gezielte Analyse Kompromissen zwischen Raum und Zeit sowohl theoretische Einsichten als auch praxisnahe Werkzeuge liefert
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Maliciously Circuit-Private FHE from Information-Theoretic Principles
Get PDFFully homomorphic encryption (FHE) allows arbitrary computations on encrypted data. The standard security requirement, IND-CPA security, ensures that the encrypted data remain private. However, it does not guarantee privacy for the computation performed on the encrypted data. Statistical circuit privacy offers a strong privacy guarantee for the computation process, namely that a homomorphically evaluated ciphertext does not leak any information on how the result of the computation was obtained. Malicious statistical circuit privacy requires this to hold even for maliciously generated keys and ciphertexts. Ostrovsky, Paskin and Paskin (CRYPTO 2014) constructed an FHE scheme achieving malicious statistical circuit privacy.
Their construction, however, makes non-black-box use of a specific underlying FHE scheme, resulting in a circuit-private scheme with inherently high overhead.
This work presents a conceptually different construction of maliciously circuit-private FHE from simple information-theoretical principles. Furthermore, our construction only makes black-box use of the underlying FHE scheme, opening the possibility of achieving practically efficient schemes. Finally, in contrast to the OPP scheme in our scheme, pre- and post-homomorphic ciphertexts are syntactically the same, enabling new applications in multi-hop settings
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Algebraic Restriction Codes and Their Applications
Get PDFConsider the following problem: You have a device that is supposed to compute a linear combination of its inputs, which are taken from some finite field. However, the device may be faulty and compute arbitrary functions of its inputs. Is it possible to encode the inputs in such a way that only linear functions can be evaluated over the encodings? I.e., learning an arbitrary function of the encodings will not reveal more information about the inputs than a linear combination.
In this work, we introduce the notion of algebraic restriction codes (AR codes), which constrain adversaries who might compute any function to computing a linear function. Our main result is an information-theoretic construction AR codes that restrict any class of function with a bounded number of output bits to linear functions. Our construction relies on a seed which is not provided to the adversary.
While interesting and natural on its own, we show an application of this notion in cryptography. In particular, we show that AR codes lead to the first construction of rate-1 oblivious transfer with statistical sender security from the Decisional Diffie-Hellman assumption, and the first-ever construction that makes black-box use of cryptography. Previously, such protocols were known only from the LWE assumption, using non-black-box cryptographic techniques. We expect our new notion of AR codes to find further applications, e.g., in the context of non-malleability, in the future
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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