Blockchain Papers

Yihan Jiang, Yong Li, Yan Zhu

With the development of Blockchain, more and more distributed cryptocurrencies continue to emerge. Most of these currencies use cryptographic techniques (such as zero-knowledge proofs, ring signatures, etc.) to enhance privacy protection, but at the same time the regulatory authorities have no access to audit transactions. Most existing auditing schemes are based on centralized system and cannot be directly applied to distributed cryptocurrencies. Therefore, an Auditable Zerocoin with User Awareness (AZUA) scheme which supports privacy protection and auditability simultaneously is proposed in this paper. Aiming to ensure that auditors can audit Zerocoin's transactions, auditability is defined in this paper. Meanwhile, in order to prevent auditors from abusing their power, a new security property is proposed: user awareness auditing. Moreover, taking transaction privacy issue into consideration, indistinguishability of audit information is defined. The transaction auditing from auditors is achieved in AZUA through the encryption scheme, which ensures the honesty of the auditors by introducing a commitment mechanism and that the users can be aware of whether they have been audited according to randomized public keys. Finally, it is proved that the scheme can satisfy auditability, user awareness auditing and indistinguishability of audit information simultaneously.

Kazi Md. Rokibul Alam, Shinsuke Tamura, Sazia Rahman, Yasuhiko Morimoto

This paper improves the performance of the revised-simplified verifiable re-encryption mixnet (R-SVRM) based e-voting scheme by introducing confirmation numbers (CNs) that are used in the CN based e-voting scheme. Although CN based and R-SVRM based schemes had made e-voting schemes more practical by excluding zero knowledge proof (ZKP) that requires large volume of computations, still they are not efficient enough. Namely, the CN based scheme adopts RSA encryption functions that are not probabilistic or commutative, therefore to satisfy essential requirements of elections, extra random factors are necessary for individual votes, election authorities must sign on votes and they must keep encryption keys as their secrets. On the other hand, although the R-SVRM based scheme uses ElGamal encryption functions that are probabilistic and commutative, vote forms in it is complicated, i.e., vote forms consist of at least 3 items and they include information about candidates as exponents. The improved scheme simplifies vote forms by exploiting CNs, and extensively reduces the number of operations required for individual votes. Also, the scheme successfully satisfies all essential requirements of e-voting systems, i.e., it is endowed with features about privacy, robustness, accuracy, incoercibility and fairness as CN based and R-SVRM based schemes are.

Peter B. Rønne, Arash Atashpendar, Kristian Gjøsteen, Peter Y. A. Ryan

We present an approach for performing the tallying work in the coercion-resistant JCJ voting protocol, introduced by Juels, Catalano, and Jakobsson, in linear time using fully homomorphic encryption (FHE). The suggested enhancement also paves the path towards making JCJ quantum-resistant, while leaving the underlying structure of JCJ intact. The exhaustive, comparison-based approach of JCJ using plaintext equivalence tests leads to a quadratic blow-up in the number of votes, which makes the tallying process rather impractical in realistic settings with a large number of voters. We show how the removal of invalid votes can be done in linear time via a solution based on recent advances in various FHE primitives such as hashing, zero-knowledge proofs of correct decryption, verifiable shuffles and threshold FHE. We conclude by touching upon some of the advantages and challenges of such an approach, followed by a discussion of further security and post-quantum considerations.

Yuxi Li, Fucai Zhou, Zifeng Xu

Offline electronic cash is a new and well-acknowledged type of e-cash scheme that can release the bank from participating in every spending protocol. However, it is still an unsolved problem to design a secure and efficient fair offline e-cash scheme. Considering this problem, in this paper, we have proposed a fair offline electronic cash scheme with multiple banks in pairing-based instantiation. We adopt Groth–Sahai non-interactive zero-knowledge proof technology in our scheme, to design non-interactive e-cash transactions. Additionally, inspired by Water’s group signature, our solution supports not only multiple users, but also users with accounts in different banks. Moreover, our scheme has efficient double-spending checking and a fair control mechanism. We have formally defined the security properties of the scheme in a standard model, and provided the detailed security proofs of the security properties concerning chosen ciphertext attack (CCA) anonymity, unforgeability and traceability. Analysis and comparison show that our scheme has advantages both in security and in efficiency.

Manuel Abarca

Spanish Abstract: Las Ofertas Zero-Rating son una práctica común en el mercado de las telecomunicaciones, tanto a nivel nacional como internacional. Estas consisten en la posibilidad de que el usuario pueda utilizar determinadas aplicaciones/software/programas en su teléfono móvil, sin afectar el monto de datos contratado con su proveedor de acceso. Si bien esta práctica resulta en principio beneficiosa para el consumidor, desde la perspectiva de los desarrolladores de apps y las mismas compañías telefónicas surgen dudas respecto a sus efectos. Las Ofertas Zero-Rating pueden analizarse desde el punto de vista del derecho de la competencia y desde el punto de vista regulatorio, a partir del denominado principio de la neutralidad de red, consagrado en Chile en la ley 20.453 de 2010. Desde un punto de vista de competencia, estas ofertas constituyen acuerdos verticales entre proveedores de acceso y aplicaciones que otorgan preferencia de uso a estas últimas. Dependiendo de determinados requisitos, y especialmente de la posición dominante de los proveedores y la teoría del daño aplicable, estas ofertas pueden generar riesgos anticompetitivos que requieran la intervención de las autoridades de competencia. Desde el punto de vista regulatorio, las ofertas pueden ser analizadas a partir del principio de la neutralidad de red. Este principio de la gobernanza de internet establece, básicamente, que los proveedores de internet (ISP) deben asegurar un tráfico de datos igualitario y no discriminatorio entre los desarrollares de servicios (páginas web, apps, etc.) y los usuarios finales que acceden a internet. En este sentido, las Ofertas Zero-Rating constituyen en principio un incumplimiento de sus premisas. Sin embargo, dado los altos requisitos actuales que se exigen para que estas prácticas sean subsumibles en el marco de los ilícitos de competencia, y la actual interpretación de la Subsecretaría de Telecomunicaciones respecto al sentido y alcance de las reglas de neutralidad de red, las Ofertas Zero-Rating no han sido analizadas correctamente, ni mucho menos sancionadas. Así, la actual regulación chilena sobre neutralidad de red constituye más bien una mera declaración, que carece de aplicación práctica. El objetivo del presente trabajo es determinar los pro y los contra del enforcement del principio de neutralidad de red respecto de las Ofertas Zero-Rating, para finalmente concluir que, dada sus particularidades, se trata de un principio reconocido en la legislación que es transversal a ambas áreas, debiendo armonizarse su interpretación. English Abstract: Zero-Rating are a common practice in the national and international telecommunications markets. They consist in the possibility of the user to use certain apps and softwares in his mobile phone without affect the total amount of data contracted with his service provider to be used. Although this practice could increase the consumer welfare, its effects on app developers and telecommunication companies are dubious. Zero-Rating can be analyzed as a matter of competition law and as a matter of the regulation of Net Neutrality, according to the Chilean Law (Law 20.453 of 2010). As a matter of competition law, Zero-Rating consists in vertical agreements between service providers and apps in order to give them a certain access preference. As a matter of net neutrality, which prohibits any form of discrimination of internet service providers (ISP’s) between content providers (web pages, apps, etc.) and users, Zero-Rating could be an infringement of the Chilean Net Neutrality Law. In Chile, Zero-Rating doesn’t have any kind of enforcement. As a matter of competition, it doesn’t qualify as an abuse of dominant position (in the terms of Art. 3 b) of the Chilean Competition Act, the DL 211). As a matter of regulation, the actual interpretation of the telecommunications regulator (The Chilean SUBTEL) permits these practices. The objective of this paper is to determine the pros and cons of an eventual competition and Net Neutrality enforcement against Zero-Rating in the Chilean Law.

Mojmir Simersky

The paper addresses the problem of zero–coupon yield curve (YC) estimation from a portfolio of coupon–bearing instruments, primarily coupon bonds. A fast and stable iterative procedure is proposed and implemented. The optimization problem is formulated in a matrix form, the principal cashflow matrix having the dimension given by the number of instruments (bonds) and the number of knots on the time axis. The number of instruments is arbitrary, as well as the number of time knots. In our concept of ”equivalent cashflows”, each future cashflow at a time t is replaced by two cashflows, one at the left, the other at the right knot respective to the time t. We solve then a simplified problem of estimating the YC from a portfolio of instruments whose future cashflows occur only at predefined times. The method allows for further additional constraints, e.g., an ultimate forward rate fixing or predefined discount factor at some time. We touch also on the asymptotic case of a very dense partitioning of the time axis. The optimization is carried out in the space of forward rate functions of the simplest form – zero–degree splines, i.e., piecewise constant functions. Our approach is thus a generalization of the bootstrap method with no requirements on the bond maturity ladder and, at the same time, with optional smoothing. This work relates to our previous article [4], where the idea of equivalent cashflows was introduced. Czech bond yields estimated by the proposed method can be found in.

Crystal B. Lake

Previous articleNext article FreeAntiquarianism as a Vital Historiography for the Twenty-First CenturyCrystal B. LakeCrystal B. LakeWright State University Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreIn his famous essay from 1950, Arnold Momigliano countered the stereotype of eighteenth-century antiquaries and their modern successors as the “muddle-headed” collectors of old things and odd facts (297). Antiquarianism was not, Momigliano argued, the pastime of eccentric fetishists who hoarded old stuff just because it was old; rather, antiquarianism established the foundation of so-called “modern” history by making the study of primary source material, including physical remains, the bedrocks on which historians’ claims about the past should be based. As Momigliano explained, “religious and political disputations” in the seventeenth century swirled around the work of traditional historians (295). Wary that polemical biases had corrupted the writings of traditional historians, antiquaries bypassed secondary accounts of the past and went straight to examining primary, often nonliterary, sources instead. In so doing, they established archival documents and archaeological artifacts as the most reliable evidence for historical study—and future historians found themselves tasked with discovering and describing such evidence before they could proceed to interpreting it.Since 1950, scholars have followed Momigliano’s lead and examined how antiquaries disciplined historical inquiry.1 Antiquarianism, however, has come under fire again in the twenty-first century in two documents, both of which were collaboratively authored polemics published online that criticized the fields of history and Victorian literary studies. The V21 Collective’s “Manifesto” (2015) and The Wild on Collective’s “Theses on Theory and History” (2018) advocate for reforming the ways that academics study the past by censuring—in one case explicitly and in the other case implicitly—the antiquarianism that now operates under the guise of modern historiography. These twenty-first century dismissals of antiquarianism share the assumptions of Momigliano’s midcentury readers: that antiquaries collect the detritus of the past for its own sake. They also, however, accept the argument that Momigliano made: that antiquarianism constitutes a rigorous method of study that prioritizes the discovery of history’s bare facts over theories.Yet the work of two influential antiquaries, John Aubrey (1626–97) and John Britton (1771–1857), suggests that neither antiquarianism’s detractors nor its devotees have quite told the whole story about what antiquarianism as a methodology can entail. Antiquaries were not “muddle-headed” fetishists for objects or for facts who abjured from varieties of speculation. For antiquaries like Aubrey and Britton, old objects had the power to reveal facts about the past. Although this power meant that those old objects constrained interpretive possibilities, it just as often meant that those old objects enticed antiquaries into speculating about matters that exceeded the physical as well as the temporal boundedness of the objects themselves. In this way, antiquarianism was not the deadening methodology that twenty-first century academics who are eager to escape the tyranny of positivism should dismiss. Rather, antiquarianism is a method they might consider returning to for the ways it once offered scholars opportunities to translate their careful, close scrutiny of lively historical artifacts into theories that transcended the boundaries between the past and the present as well as between the personal and the political.In the process of leveling critiques of the “positivism” that they take to characterize contemporary historical research, both the V21 and the Wild on Collectives isolate antiquarianism as a methodology their readers should disavow. On the one hand, both collectives use antiquarianism to denote a fetish for primary sources and the facts they preserve; on the other hand, they use antiquarianism to signify an interpretive mode that turns the facts one finds in primary sources into constrained interpretations of sociocultural phenomena that render them as the mere effects of the specific historical contexts—particular slices of time in particular places—in which they occurred.The V21 and the Wild on Collectives claim that giving up what old antiquarian sensibilities persist in historical scholarship will lead scholars to welcome the opportunities their subjective points of view present for developing theories about their old objects of study that are relevant for today’s readers and their political concerns. The V21 Manifesto explicitly uses the phrase “bland antiquarianism” to denigrate what they describe as the “positivist historicism” that typifies the methods of nineteenth-century literary studies: “a mode of inquiry that aims to do little more than exhaustively describe, preserve, and display the past” (1).2 The most noxious “symptoms” of positivist historicism include “a fetishization of the archival” and “an endless accumulation of mere information” (1). “At its worst,” the V21 Collective maintains, “positivist historicism devolves into … bland antiquarianism,” the “primary affective mode” of which “is the amused chuckle” (1).In contrast to the limpid scholarship produced by bland antiquarianism, the V21 Collective implores their readers to practice “post-historicist interpretation” (7). Post-historicist interpretation entails embracing “presentism” and emphasizing “form” over facts (7–8). Presentist, formalist critics acknowledge that their research is “motivated by features of [their] own moment” and examine how “forms persist across artificially designated historical periods” (8, emphasis added). Consequently, the V21 Collective suggests that rejecting bland antiquarianism will produce more politicized as well as more germane studies of nineteenth-century literature for twenty-first century readers.The Wild on Collective does not explicitly single out antiquarianism for a bemused chuckle, but similarly attempts to convince contemporary historians to abandon what antiquarian sensibilities remain in the discipline of history. Specifically, the Wild on Collective calls for historians to relinquish their presumption that “past events are objectively available for discovering, description, and interpretation” (I.4) through “immediately observable, preferably archival, evidence” (I.2). The Wild on Collective, therefore, conflates “positivism” with the historiography that became popularized during the Enlightenment—the period when historians incorporated antiquarianism into their studies of the past, as Momigliano and others have shown (I.1). The first thesis tendered by the Wild on Collective declares, for example, that “[a]cademic history has never managed to transcend its eighteenth century origins as an empiricist enterprise” (I.1). The Wild on Collective spares a generous thought for David Hume’s skepticism but moves quickly to denounce all those other eighteenth-century historians who privileged a “scientistic [sic] method” for “gathering facts” about the past in the archives they fetish (I.1).Like the V21 Collective, the Wild on Collective proposes that abandoning the search for facts in archival sources will free contemporary historians to practice “critical” or “theorized history:” a method for studying the past in which historians can translate their subjective experiences of the present into politically relevant studies of the past as “structure” (III.2 and “Coda”). “Structure,” in the Wild on Collective’s manifesto, appears to be similar to “form” in the V21 Collective’s manifesto. For both collectives, forms or structures exist in dynamic relationships with their perceivers in the present. The study of archival materials, therefore, fails both to divulge and to produce a comprehensive understanding of forms or structures that must, to a degree, always be theorized.The emphasis on “theory” marks the telos in both the V21 and Wild on Collective’s manifestos: the final transformation of their rejection of antiquarianism’s imperative that knowledge about the past should be factual and derived from primary sources into a refutation of scholarship that aims to document historical “context.” In this regard, the two collectives enter as the chorus affirming Bruno Latour’s declaration that “context stinks.” Yet without perhaps realizing it, both collectives also thereby reintroduce antiquarian sensibilities about what historical objects of study are, and what they do, back into their reformist methodologies.Latour first declared that “context stinks” in his 2005 Reassembling the Social. In an imagined dialogue between Latour and a student struggling to practice his actor-network-theory (ANT), Latour attributes the quip to the architect Rem Koolhaas. Koolhaas actually said “fuck context” in 1995 as a way of ventriloquizing what really big buildings might have to say for themselves.3 Latour uses the more delicate phrasing to admonish the student who is about to turn to something conceptually “bigger” than the individual case studies that she has gathered for her dissertation in order to conclude what her research has illustrated. The student’s other advisors want her descriptive “case studies to ‘lead to some useful generalization,’” and so the student seeks to find “a frame” or a “typology” they can use to “compare, explain, [and] generalize” (149). For Latour, then, context names that which researchers presume to be prior to, bigger than, outside of their individual case studies.Latour’s dismissal of context reflects the core philosophical tenet from which the method of his ANT arises. That is, Latour argues that researchers should treat all of their objects of study—even, literally, the objects that they study—as actors, or, “things that do things”: entities vested with varieties of autonomous agency to influence “states of affairs” (We Have Never Been Modern 104). ANT is therefore a method whereby the task of the researcher is simply to “follow the actors” and describe what it is that they do. Applied to studies of the past, in other words, context stinks when a scholar presumes that old ideas, events, or institutions determine the existence and significance of her objects of study.Latour, therefore, doesn’t think that historical contexts stink. If an object of study refers to or wanders through an old idea, event, or institution, then it has led an ANT researcher to follow it into those historical contexts. Consequently, had Latour’s dialogue in Reassembling the Social occurred between him and V21 and Wild on Collectives, Latour would likely have insisted that their objects of study did not need to be theorized; they theorize themselves. Likewise, Latour would likely have pointed out that the critic as well as the historian have always been “presentist” (“Manifesto” 8) or “psychically, epistemologically, ethically, and politically implicated in their objects of study” (“Theses” III.6). Such realizations are borne, in fact, out of practicing Latour’s actor-network-theory. If an actor doesn’t act, Latour might say, then an ANT researcher has nothing to describe or theorize. This means that the critics’ or historians’ objects of study act by existing as objects of study in the present—and as such, they remain capable of not only revealing facts and inviting researchers to exploring historical contexts but also of leading researchers to theorize about forms as well as structures.Noah Heringman and I have suggested elsewhere that Romantic antiquarianism was akin to Latour’s ANT.4 Beginning in the seventeenth century, antiquaries like John Aubrey granted antiquities the power “to speak” or “give evidence for themselves” (Monumenta 1.32). In so doing, antiquarianism developed in ways that anticipated Latour’s rendering of objects as “actors” or things that do things. The antiquaries’ task was to find, follow, and describe old objects, which they understood to be vested with the agency to preserve and make manifest facts about the past. Once antiquities were understood to be things that could do things, however, they proved capable of doing a lot of things—including affecting the antiquaries who encountered them personally and inciting those antiquaries to engage in varieties of speculation.Aubrey’s antiquarian research offers one representative example of how antiquarianism could yield political, personal, and theoretical interpretations about the past while still keeping such interpretations tethered to the antiquaries’ objects of study and the facts they also yielded. In 1845, John Britton published the first comprehensive biography of Aubrey. Britton learned about Aubrey’s antiquarianism four decades earlier while writing the first volume of what would become Britton and Edward Wedlake Brayley’s (1773–1854) The Beauties of England and Wales (1800–1820): a county-by-county survey of the notable sites, including especially the antiquities, to be seen in England and Wales. The first volume Britton tackled was the volume on Wiltshire county, famous for its henges and the place that Britton himself called home. Britton read Aubrey’s seventeenth-century manuscript notes on Wiltshire in 1800 and discovered a kindred spirit. The two men had grown up nearly a century and half apart in the same region, and “[w]hat Aubrey wrote of himself … applie[d] in many respects to myself,” Britton affirmed. (Autobiography 1.40).Britton’s biography of Aubrey honored the kinship he felt for the early antiquary by attempting to rehabilitate Aubrey’s posthumous reputation. Britton lamented that few of his “general” readers in 1845 were likely to recognize the name John Aubrey—unless, that is, they knew about Aubrey’s Miscellanies (1696). The only work that Aubrey managed to see through to publication in his lifetime, the Miscellanies had unfortunately focused on documenting evidence of supernatural phenomena: “a subject long since trodden down by the ‘march of intellect’” (Britton, Memoir 1). Organized under twenty-one headings such as “Omens,” “Apparitions,” “Blows Invisible,” and “Converse with Angels and Spirits,” Aubrey’s Miscellanies struck many readers as superstitious hogwash. As Anthony Wood (1632–95)—Aubrey’s sometime collaborator and accused plagiarizer—put it, the Miscellanies showed that Aubrey had not pursued serious inquiries into serious matters of historical fact; rather, he had “addicted himself to the whimseys and conceits of astrologers, soothsayers, and such like ignorant and superstitious writers” (quoted in Britton, Memoir 6).In his Memoir of John Aubrey, Britton maintained that the superstitious whimseys of Aubrey’s Miscellanies were simply a by-product of the historical moment in which Aubrey had lived. Everyone in the seventeenth century believed in “ghosts, in haunted houses, in witchcraft, in necromancy, in fairies, and their manufactory of grass rings, in the supernatural influence of jack-o-lanterns, or will-o’-the-wisps, and many other visionary vagaries,” Britton upheld, especially if they were from Wiltshire (Memoir 8). Even Britton had believed such things himself as a young boy and still did, sometimes.In Britton’s estimation, then, the Miscellanies was a “failing incidental,” but it was still important as a historical record of seventeenth-century beliefs that persisted into the nineteenth-century present. Since the publication of Britton’s Memoir, however, it has been commonplace for scholars to set Aubrey’s Miscellanies aside as an anomaly and proceed to rescue Aubrey’s contributions to historical studies by focusing on his unpublished manuscript materials, which include the report on England’s stone henges and extensive notes he prepared for writing county histories of Wiltshire and Surrey that Britton also prized.5Although the Miscellanies has not featured prominently in accounts of Aubrey’s or his contemporaries’ antiquarianism since Britton published his Memoir, it should have. The Miscellanies preserves aspects of antiquarianism that have been lost in the disciplinary and disciplining histories that cast early antiquaries in the role of archaeologists in spirit, if not yet in name. Specifically, the Miscellanies illustrates how an antiquary’s careful examination of old objects could produce more than just dry-as-dust facts; it could also yield personal, political, and theoretical engagements with the past that were relevant for the present. These features of antiquarianism not only compelled Britton to appreciate Aubrey and his life’s work; they also speak to the reformist demands of the V21 and Wild on Collectives.As a collection of first- and secondhand accounts of strange phenomena, Aubrey’s Miscellanies does not initially appear to be an antiquarian publication. Yet on closer inspection, Aubrey’s interest in objects and the histories they alone have the power to convey are hard to miss. The evidence that Aubrey presents throughout the Miscellanies—which suggests to him that there is an “Invisible World” that exists and “knows what we do, or incline to”—derives from observing and describing things, and such evidence assembles into a curious political history of seventeenth-century England (Miscellanies vi). The Miscellanies describes, over and over again, things that break at untimely but auspicious moments in ceremonies of state, items that fall off the walls during conspiratorial tête-à-têtes, prophecies about treachery written on old parchments that turned out to be true. Aubrey’s catalogue of strange things, therefore, also documents the English civil the the and the readers of the Miscellanies of the and that at all the and of antiquarianism and antiquities that Aubrey in his other writings to how his method for studying the past through its objects could produce the of subjective and that the more readers of the Aubrey of antiquities as objects from the past that had the of but he of his own to were often those objects that had not only the of time but also the of (Miscellanies through the of the seventeenth century, Aubrey knew that often old things in order to work of and describing the objects that had managed their escape from the past was often a Aubrey and one that with that his own research had often been (Miscellanies Aubrey his search for antiquities with “a of and he appears to have understood that antiquarianism was more as a methodology because it was capable of As Aubrey in his manuscript notes on stone an antiquary simply meant the objects that to or “give evidence for antiquities could only speak and so (Monumenta 1.32). Although the antiquities that had and an antiquary’s from they still always some to (Miscellanies is what the Miscellanies for many of Aubrey’s Although Aubrey suggests that the he had gathered in the Miscellanies the existence of an “Invisible which what we do, or incline he never more than that (Miscellanies vi). Aubrey that the in the Miscellanies was and that he as well as his readers remain in the as to what the phenomena the objects proved (Miscellanies vi). Aubrey’s to on of the he in the Miscellanies marks an moment of in the context of the over of and in the that in the seventeenth can never quite be what all those objects that and on their own were really to say about the political events that they had and to the objects in Aubrey’s Miscellanies and antiquarian imperative to to the agency of things in the to interpretation was in and of a political As Momigliano antiquaries to the of things that could speak or evidence for themselves once it became that the historians who for the past often the of Aubrey’s lifetime, historical as in about the as well as the of As the case is now with the that have been by Latour’s so it was in the first of antiquarianism’s in the seventeenth a to an in the of the The power of objects, antiquaries like Aubrey might one not the power of political who declared for themselves the to determine what the facts really a to the political imperative to or historical antiquarianism offers the V21 and the Wild on Collectives a methodology that they might than a methodology that has for politically scholarship as well as for scholarship that finds its objects of study not only capable of affecting their present but also capable of opportunities for their to engage with forms or structures and theories in the of or Aubrey’s Miscellanies is just this of and it as a record Aubrey prepared for future a collection of things that might to speak and evidence for themselves. They are still about the political that Aubrey and the of time he knew he would not They to about the of personal and that can as Aubrey the Miscellanies would always its readers with to Consequently, the antiquarianism that Aubrey’s Miscellanies can the V21 and Wild on Collectives a methodology they might than it can also them more than a few of The posthumous of Aubrey how the antiquaries’ that things from the past could and should be to speak for that they would speak without to be antiquarianism’s Aubrey was to to it was that the objects he encountered had to say with the understanding that they could only say so however, before historian to that they had and the of old things, as Momigliano has historians turned out to the same or the that antiquities for to the that they Aubrey’s readers of his Miscellanies on the personal as well as the that it they its descriptive mode and political Although Aubrey’s readers at the on the the that antiquaries for the two often to around the of political that antiquarianism was to not only Aubrey’s Miscellanies but also on other antiquaries’ claim that their of primary sources the of that had of their critics could be the eighteenth century, antiquaries to their critics’ that their own research could be politically by evidence as for and that they had from the objects they In other words, as critics into the that interpreting the past and its objects antiquaries down on their first that old objects did speak for themselves by that those objects always told the As Wiltshire wrote in all at the and at the of his of Wiltshire for example, he and his antiquaries from facts not that the study of primary evidence really did in the of facts turned however, to be a in the The of the of antiquarianism into the study of history was one in which historian could that they were ventriloquizing the facts that historical objects and because those same objects always for interpretations could always be as mere The of of Wiltshire for the to declaration by out that his of in was theoretical Britton the Beauties in he antiquarian histories for the first time and that the research antiquaries had produced in the century was and (Autobiography Britton would on to describe himself as a of an and he was the to describe Aubrey as an (Memoir Aubrey, to Britton, was the who his studies and to in its of (Memoir Aubrey’s antiquarianism as Britton to rehabilitate Aubrey’s reputation. also, however, to aspects of Aubrey’s antiquarianism that had been lost in the of hard facts in archival sources that had come to characterize the of historical study in the other words, Britton’s to describe Aubrey as an and himself as a not as his and Aubrey’s work in of nineteenth-century Britton also aspects of Aubrey’s antiquarianism, including the of its objects of study and the political, personal, and theoretical their could For example, in his Britton what it was like when he and first their in the antiquarian Once they their of county, in and up close the antiquities that they had read about and would on to describe in ways for the Britton was to of descriptive of objects of of of and of of as a of a a a to his of an and and on the produce of the like a was and of the and who not only their own and but their in and of a who the the the and to the and also the of of and he moves from observing antiquities to observing a a a and a Britton the work of earlier antiquaries who their research in the of the of and proved to and moves to antiquarianism’s for a of the the the the the V21 and Wild on Collectives, then, Britton to of there is in be which would never be or Britton believed (Autobiography The publication of Britton’s Memoir of John Aubrey was by the Wiltshire which Britton himself had to with a of young Britton from and of Antiquaries in in order to the study of antiquities in (Autobiography For Britton, the of the as well as the

Shuichi Katsumata, Ryo Nishimaki, Shota Yamada, Takashi Yamakawa

No abstract is available for this record.

Sina Shiehian

Since Gentry's breakthrough construction of fully homomorphic encryption from lattice-based assumptions (STOC 2009), homomorphic cryptography has attracted a lot of attention. In short, homomorphic cryptography schemes allow performing computation on encrypted data without knowing anything about the underlying plaintext. This branch of cryptography has become increasingly useful in building new protocols and schemes with intriguing security and functionality features. In this thesis, we continue to study the applications of homomorphic cryptography and the lattice-based techniques underlying them in realizing new and enhanced cryptographic primitives. We obtain the following results: -We construct the first noninteractive zero knowledge argument (and proof) system for all of NP from standard lattice assumptions. Noninteractive zero knowledge argument systems have found many applications in enhancing the functionality as well as the security of cryptographic schemes and protocols. Constructing noninteractive zero knowledge arguments from lattice assumption has been a long standing open question. We finally close this problem. -We consider multi-key fully homomorphic encryption (FHE) schemes. Traditional fully homomorphic encryption schemes allow computation on plaintext encrypted under a single key. The notion of multi-key fully homomorphic encryption allows homomorphic computation on data encrypted under different keys. We construct multi-key FHE schemes which are naturally dynamic: ciphertexts under new keys can join even during the homomorphic computation. -Finally, we focus on constrained pseudorandom functions (C-PRFs), which are pseudorandom functions (PRFs) with additional functional capabilities. We propose a new approach for building C-PRFs from lattices, and also significantly enhance the underlying lattice parameters.

Nir Bitansky, Akshay Degwekar

No abstract is available for this record.

Fransisca Andriani

The abundance of data available on public blockchain environments might expose users to privacy breaching. Ethereum as the largest host of blockchain-based project currently has no robust protection against such threats. In this paper, a proof-of-concept decentralized application is implemented demonstrating privacy preserving transaction flow in Ethereum environment using zero-knowledge cryptography (zk-SNARK ). The design of the application utilized an experimental package, EY Nightfall and focuses on a blind auction scenario where personal informations needs to be protected. The proof-of-concept is then analysed to weigh the financial and temporal costs of the implementations against the security advantages and was found to be feasible for non fast-paced settings and significantly large transactions.

Authors unavailable

The blockchain represented by Bitcoin, the distributed ledger system can prevent double spending effectively and other issues. But it has caused the concentration of bitcoin mining power, which completely contradicts the essential feature of the complete decentralization of the blockchain. In the blockchain system, transaction data information among users is transparently stored on the chain, and each participant can obtain a complete data backup. These transaction data are stored in an open and transparent manner on each node of the entire network, although it can prevent data forgery and tampering, it brings data privacy problems. In this paper, we propose a multi-level reward structure for the problem of centralized power calculation in the mining pool. This structure can make the miners work alone to prove the workload and obtain the reward through their own calculation power, in order to weaken the role of the mining pool. At the same time, for the data privacy security problem in the bitcoin trading system, we have improved the bitcoin puzzle, and proposed a puzzle scheme based on non-interactive zero-knowledge proof to ensure data transaction security.

Brandon Mendrick

Group signature schemes enable a set of members to anonymously sign data on behalf of the entire group. In order to prevent misuse, a designated group manager<br>has the ability to trace a given signature back to a member. Other extensions can also be realized in speci ffically designed schemes, such as veri fier local revocation (VLR) wherein only the verifi er needs information about the validity status of signing key pairs. This paper contributes two results towards group signature schemes. First, we present a new design for a group signature scheme that is secure under the standard<br>model, with common relaxations for anonymity. The scheme also enables VLR and allows for fully-dynamic groups; i.e. groups that allow members to both leave and join after creation. Secondly, we implement a preliminary version of the scheme to begin investigating the effi ciencies gained through utilizing one-time signing keys, instead of the traditional non-interactive, zero-knowledge proof systems.

Chin, Zhi Xian

Privacy is one of the major challenges which blockchain systems face today as there&#13;\nis a requirement to publish all transactions of each block in each node and all&#13;\ninformation is exposed to public scrutiny. Although there are privacy-related libraries&#13;\navailable on blockchain which distributed applications can use, there are currently no&#13;\napplications which use these libraries as the designed applications are extremely&#13;\nbasic.&#13;\nIn this paper, we introduce a decentralized application which is a proof-of-concept&#13;\nutilising zero-knowledge proofs hiding the birth date of the user while retaining the&#13;\nability to prove that the user is above a to-be-determined age.&#13;\nThe decentralized application was designed through the analysis of the capabilities of&#13;\nthe libraries as well as the investigation of potential uses which zero-knowledge&#13;\nproof can provide in scenarios where a user might desire a higher level of privacy.&#13;\nTesting of this proof-of-concept proved that it is highly feasible in terms of financial&#13;\nand temporal cost and these are comparable to that of current alternatives.&#13;\nIn the future, this proof-of-concept can be extended to other decentralized&#13;\napplication, other uses and even other blockchains as this implementation was&#13;\ndesigned with extensibility and potential blockchain agnosticism in mind.

Vipul Goyal, Aayush Jain, Amit Sahai

No abstract is available for this record.

Jingqing Zhang, Piyawat Lertvittayakumjorn, Yike Guo

No abstract is available for this record.

Gyanendra Gongal

Rabies is one of the ancient diseases known to humanity. Dog-transmitted rabies accounts for about 99% of human rabies cases in rabies-endemic regions.[1] It is estimated that 59,000 people die from rabies every year.[2] Economic impact of rabies in livestock production is considered high, but surveillance data are missing. Elimination of human rabies is feasible and sustainable if rabies is controlled at the source, i.e., dog. Rabies elimination is a global public good as thousands of people are still dying due to this vaccine-preventable disease mostly in Africa and Asia! It is unacceptable to see premature deaths of young children due to rabies when proof of concept, technical knowledge, and tools are at our disposal. Unfortunately, rabies remains a neglected disease affecting poor-marginalized population in rabies-endemic countries of Asia and Africa due to competing priorities and lack of political will. Rabies elimination has a social, technical, organizational, and political dimension and demands multidisciplinary and multisectoral approaches. Considering that rabies control and subsequent elimination is a model for operationalization of One Health, the WHO in partnership with Food and Agriculture Organization of the United Nations, World Organization for Animal Health, and Global Alliance for Rabies Control came up with a vision of encouraging rabies-endemic countries to achieve zero human deaths from dog-mediated rabies by 2030 worldwide in line with the Sustainable Development Goals' target date of 2030. The rationale for the global strategy is to build on lessons learned, to align country and regional successes into a global strategy with a common goal of eliminating dog-mediated human rabies by 2030. India is a country of more than one billion population, and it has the highest burden of rabies in the world. Remarkable progress has been done in the last 12 years in phasing out of nerve–tissue rabies vaccine by both introducing cost-effective intradermal rabies vaccination and making accessible and available vaccine and rabies immunoglobulin for postexposure prophylaxis in public hospitals. A pan India survey was supported by the WHO to capture the programmatic experiences of rabies prevention and control with emphasis on human rabies, which provided a clear ground reality of accessibility, availability, and affordability of human rabies vaccine and rabies immunoglobulin in India with some recommendations for the improvement of surveillance, reporting, and policy advocacy. A multicenter study on burden of rabies was carried out with the WHO support in 2003, and it is appreciable that the National Centers for Disease Control and Indian Council of Medical Research have taken initiative to re-assess burden of human rabies in India which may show the impact of rabies control activities in human rabies incidence. All these assessments should lead to policy advocacy for operationalizing pan India rabies elimination campaign with goal of zero human rabies by 2030. Success stories have been generated for model dog rabies vaccination and animal birth control program in selected urban areas of India, but much needs to be done for surveillance and control of dog rabies under government leadership and ownership. The veterinary sector in India has a greater social responsibility in controlling dog rabies so that public fear of dog as a source of rabies is changed and livestock and people are no more victim of dog-mediated rabies. Investing in rabies control and elimination strengthens health systems, improves equity and access to healthcare, and contributes to sustainable development. There is a need for strong political commitment matched with equally robust activities, and India will have to play a proactive role to move South Asia Rabies Elimination campaign as it shares long border with rabies-endemic countries in South Asia.

Hankun Ko

This dissertation is concerned with the zeros of holomorphic Hecke cusp forms in the space of newforms. We estimate a lower bound for the number of zeros on the imaginary axis and on the vertical line R(z)=1/2 in the upper half plane, both of which are outside the unit circle centered at the origin, and we denote these by δ1 and δ2 respectively. Ghosh and Sarnak call those zeros that lie on the rays 'real' including the arc z=exp (iθ), π/3 ≤ θ ≤ π/2, and they showed that a lower bound for the zeros on those geodesic lines is C log k for all sufficiently large weight k for the level 1 case. We extend their results to the newforms with levels N which are positive integers not divisible by 4 on δ2, and N which are positive integers on δ1. On δ2 we have C log k zeros if the weight k is sufficiently large and on δ1 we assume a nonnegativity result on the first negative Hecke eigenvalue and get a conditional result C log k zeros as the weight k goes to infinity. The analysis is closely related to the knowledge of Hecke eigenvalues λf (n). Most importantly it requires Deligne's bound λf (n) n^e (for every e > 0) with which we look into the proof of Theorem 3.1 in Ghosh and Sarnak cite[1], and get the same the approximation theorem for any level in Chapter 2. The estimation of zeros on δ1 also requires a `good' upper bound for the first negative Hecke eigenvalue for which we investigate an upper bound for central values of Hecke L-functions and a nonnegativity result on those values. Those will be studied in Chapters 3 and 4. In Chapter 5 we estimate lower bounds for the number of zeros on δi , i = 1, 2.

Anton Bäckström

Zero-knowledge password policy checks (ZKPPC) were introduced in Kiefer and Manulis’ report from 2014. The protocol aimed to solve the longstanding issue with servers requiring clients to provide their password in plain text to ensure its strength. Their protocol was intended to eliminate the need for users to trust the server to store and handle passwords correctly while simultaneously allowing the server to know that the registered password was strong enough. This thesis has investigated the soundness of the protocol by Kiefer and Manulis and will present three new zero-day vulnerabilities discovered in the process. The vulnerabilities allow a dishonest user to prove adherence to the policy for invalid passwords. Additionally, the thesis presents our new Proof of Inequality which prevents one of these vulnerabilities, as well as an extension for an incomplete part of the protocol. The two remaining zero-day vulnerabilities are weaknesses in the protocol left for future research.

Manish Kumar Singh, Yichen Han

No abstract is available for this record.

Alex Lombardi, Willy Quach, Ron D. Rothblum, Daniel Wichs · 5 authors

No abstract is available for this record.

Alessandro Chiesa, Peter Manohar, Nicholas Spooner

No abstract is available for this record.

Khoa Nguyen, Khai Hanh Tang, Huaxiong Wang, Neng Zeng

No abstract is available for this record.

Matthew Coudron, William Slofstra

We study the problem of approximating the commuting-operator value of a two-player non-local game. It is well-known that it is $\mathrm{NP}$-complete to decide whether the classical value of a non-local game is 1 or $1- ε$. Furthermore, as long as $ε$ is small enough, this result does not depend on the gap $ε$. In contrast, a recent result of Fitzsimons, Ji, Vidick, and Yuen shows that the complexity of computing the quantum value grows without bound as the gap $ε$ decreases. In this paper, we show that this also holds for the commuting-operator value of a game. Specifically, in the language of multi-prover interactive proofs, we show that the power of $\mathrm{MIP}^{co}(2,1,1,s)$ (proofs with two provers, one round, completeness probability $1$, soundness probability $s$, and commuting-operator strategies) can increase without bound as the gap $1-s$ gets arbitrarily small. Our results also extend naturally in two ways, to perfect zero-knowledge protocols, and to lower bounds on the complexity of computing the approximately-commuting value of a game. Thus we get lower bounds on the complexity class $\mathrm{PZK}$-$\mathrm{MIP}^{co}_δ(2,1,1,s)$ of perfect zero-knowledge multi-prover proofs with approximately-commuting operator strategies, as the gap $1-s$ gets arbitrarily small. While we do not know any computable time upper bound on the class $\mathrm{MIP}^{co}$, a result of the first author and Vidick shows that for $s = 1-1/\text{poly}(f(n))$ and $δ= 1/\text{poly}(f(n))$, the class $\mathrm{MIP}^{co}_δ(2,1,1,s)$, with constant communication from the provers, is contained in $\mathrm{TIME}(\exp(\text{poly}(f(n))))$. We give a lower bound of $\mathrm{coNTIME}(f(n))$ (ignoring constants inside the function) for this class, which is tight up to polynomial factors assuming the exponential time hypothesis.