The vast majority of communication on the Internet and private networks heavily relies on Public-key infrastructure (PKI). One possible solution, to avoid complexities around PKI, is to use Password Authenticated Key-Exchange (PAKE) protocols. PAKE protocols enable a secure communication link between the two parties who only share a low-entropy secret (password). PAKEs were introduced in the 1990s, and with the introduction of the first security models and security proofs in the early 2000s, it was clear that PAKEs have a potential for wide deployment - filling the gap where PKI falls short. PAKEs' PKI-free nature, resistance to phishing attacks and forward secrecy are just some of the properties that make them interesting and important to study. This dissertation includes three works on various aspects of PAKEs: an attack on an existing PAKE proposal, an application of PAKEs in login (for password leak detection) and authentication protocols (HoneyPAKEs), and a security analysis of the J-PAKE protocol, that is used in practice, and its variants. In our first work, we provide an empirical analysis of the zkPAKE protocol proposed in 2015. Our findings show that zkPAKE is not safe against offline dictionary attacks, which is one of the basic security requirements of the PAKE protocols. Further, we demonstrate an implementation of an efficient offline dictionary attack, which emphasizes that, it is necessary to provide a rigorous security proof when proposing a new protocol. In our second contribution, we propose a combined security mechanism called HoneyPAKE. The HoneyPAKE construction aims to detect the loss of password files and ensures that PAKE intrinsically protects that password. This makes the PAKE part of the HoneyPAKE more resilient to server-compromise and pre-computation attacks which are a serious security threat in a client-server communication. Our third contribution facilitates the wider adoption of PAKEs. In this work, we revisit J-PAKE and simplify it by removing a non-interactive zero knowledge proof from the last round of the protocol and derive a lighter and more efficient version called sJ-PAKE. Furthermore, we prove sJ-PAKE secure in the indistinguishability game-based model, the so-called Real-or-Random, also satisfying the notion of perfect forward secrecy.
Zero-Knowledge proofs (ZKPs) enable proving of mathematical statements, revealing nothing but their validity. We design an authentication sys-tem with a ZKP as a password verification mech-anism within the Extensible Authentication Pro-tocol (EAP) framework. Designing a secure pass-word authentication system requires us to adopt security practices for protecting ourselves against the vulnerabilities of passwords. Integrating said practices is not trivial because of the tight cou-pling with the password verification method.
Quantum communication has shown astonishingly fast development taking the advantage of quantum computation power that is being developed by technology giants like IBM, Google. The security issues and communication gaps caused by these quantum computers must be curled by the quantum computing methods. There are situations where the security of data is of less concern than knowing the fact “whether the data is tempered or not”. The Fingerprinting technique provides such knowledge by creating fingerprints of such important data and keeping the record of the temperament of data. Quantum Fingerprinting (QF) follows a procedure of creation of fingerprints of data and uses a referee which tells whether the fingerprint strings match or not. In a dilemmatic situation of fingerprinting, compromising either with security or speed, the paper focuses on achieving the removal of the referee and adding some security. This paper uses the power of Zero-Knowledge Proof (ZKP) to improve security as well as removes the use of referees in QF. The Zero Knowledge Proof is a protocol by which one party can prove to another party that they know the value “X”, without conveying any information apart from the fact that they are deemed to know “X”. Thus, embedding the curse of Zero-Knowledge Protocol to quantum fingerprinting gives Quantum Cursed Fingerprinting (QCF) the power of security and removal of the referee to match the fingerprints.
Most of the existing identity management is the centralized architecture that has to validate, certify, and manage identity in a centralized approach by trusted authorities. Decentralized identity is causing widespread public concern because it enables to give back control of identity to clients, and the client then has the ability to control when, where, and with whom they share their credentials. A decentralized solution atop on blockchain will bypass the centralized architecture and address the single point of the failure problem. To our knowledge, blockchain is an inherited pseudonym but it cannot achieve anonymity and auditability directly. In this paper, we approach the problem of decentralized identity management starting from the designated-verifier anonymous credential (DVAC in short). DVAC would assist to build a new practical decentralized identity management with anonymity and auditability. Apart from the advantages of the conventional anonymous credential, the main advantage of the proposed DVAC atop blockchain is that the issued cryptographic token will be divided into shares at the issue phase and will be combined at the showing credential phase. Further, the smooth projective hash function ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi mathvariant="sans-serif">SPHF</a:mi> </a:math> in short) is regarded as a designated-verifier zero-knowledge proof system. Thus, we introduce the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" id="M2"> <d:mi mathvariant="sans-serif">SPHF</d:mi> </d:math> to achieve the designated verifiability without compromising the privacy of clients. Finally, the security of the proposed DVAC is proved along with theoretical and experimental evaluations.
Yeow Meng Chee, Tuvi Etzion, Han Mao Kiah, Alexander Vardy
<p style='text-indent:20px;'>The Hamming ball of radius <inline-formula><tex-math id="M1">\begin{document}$ w $\end{document}</tex-math></inline-formula> in <inline-formula><tex-math id="M2">\begin{document}$ \{0,1\}^n $\end{document}</tex-math></inline-formula> is the set <inline-formula><tex-math id="M3">\begin{document}$ \mathcal{B}(n,w) $\end{document}</tex-math></inline-formula> of all binary words of length <inline-formula><tex-math id="M4">\begin{document}$ n $\end{document}</tex-math></inline-formula> and Hamming weight at most <inline-formula><tex-math id="M5">\begin{document}$ w $\end{document}</tex-math></inline-formula>. We consider injective mappings <inline-formula><tex-math id="M6">\begin{document}$ \varphi : \{0,1\}^m \to \mathcal{B}(n,w) $\end{document}</tex-math></inline-formula> with the following <i>domination property:</i> every position <inline-formula><tex-math id="M7">\begin{document}$ j \in [n] $\end{document}</tex-math></inline-formula> is dominated by some position <inline-formula><tex-math id="M8">\begin{document}$ i \in [m] $\end{document}</tex-math></inline-formula>, in the sense that if position <inline-formula><tex-math id="M9">\begin{document}$ i $\end{document}</tex-math></inline-formula> in <inline-formula><tex-math id="M10">\begin{document}$ {\mathit{\boldsymbol{x}}} \in \{0,1\}^m $\end{document}</tex-math></inline-formula> is "switched off" (equal <i>zero</i>), then necessarily position <inline-formula><tex-math id="M11">\begin{document}$ j $\end{document}</tex-math></inline-formula> in its image <inline-formula><tex-math id="M12">\begin{document}$ \varphi({\mathit{\boldsymbol{x}}}) $\end{document}</tex-math></inline-formula> is switched off. This property may be described more precisely in terms of a bipartite <i>domination graph</i> <inline-formula><tex-math id="M13">\begin{document}$ G = \bigl([m] \cup [n], E\bigr) $\end{document}</tex-math></inline-formula> with no isolated vertices; for all <inline-formula><tex-math id="M14">\begin{document}$ (i,j) \in E $\end{document}</tex-math></inline-formula> and all <inline-formula><tex-math id="M15">\begin{document}$ {\mathit{\boldsymbol{x}}}\in \{0,1\}^m $\end{document}</tex-math></inline-formula>, we require that <inline-formula><tex-math id="M16">\begin{document}$ x_i = 0 $\end{document}</tex-math></inline-formula> implies <inline-formula><tex-math id="M17">\begin{document}$ y_j = 0 $\end{document}</tex-math></inline-formula>, where <inline-formula><tex-math id="M18">\begin{document}$ {\mathit{\boldsymbol{y}}} = \varphi({\mathit{\boldsymbol{x}}}) $\end{document}</tex-math></inline-formula>. Although such domination mappings recently found applications in the context of coding for high-performance interconnects, to the best of our knowledge, they were not previously studied. The concept of domination mapping is thus interesting from both practical and combinatorial points of view. <p style='text-indent:20px;'>In this paper, we begin with simple necessary conditions for the existence of an <i><inline-formula><tex-math id="M19">\begin{document}$ (m,n,w) $\end{document}</tex-math></inline-formula>-domination mapping <inline-formula><tex-math id="M20">\begin{document}$ \varphi : \{0,1\}^m \to \mathcal{B}(n,w) $\end{document}</tex-math></inline-formula></i>. We then provide several explicit constructions of such mappings, which show that the necessary conditions are also sufficient when <inline-formula><tex-math id="M21">\begin{document}$ w = 1 $\end{document}</tex-math></inline-formula>, when <inline-formula><tex-math id="M22">\begin{document}$ w = 2 $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M23">\begin{document}$ m $\end{document}</tex-math></inline-formula> is odd, or when <inline-formula><tex-math id="M24">\begin{document}$ m \leqslant 3w $\end{document}</tex-math></inline-formula>. One of our main results herein is a proof that the trivial necessary condition <inline-formula><tex-math id="M25">\begin{document}$ | \mathcal{B}(n,w)| \geqslant 2^m $\end{document}</tex-math></inline-formula> is, in fact, sufficient for the existence of an <inline-formula><tex-math id="M26">\begin{document}$ (m,n,w) $\end{document}</tex-math></inline-formula>-domination mapping whenever <inline-formula><tex-math id="M27">\begin{document}$ m $\end{document}</tex-math></inline-formula> is sufficiently large. We also present a polynomial-time algorithm that, given any <inline-formula><tex-math id="M28">\begin{document}$ m $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M29">\begin{document}$ n $\end{document}</tex-math></inline-formula>, and <inline-formula><tex-math id="M30">\begin{document}$ w $\end{document}</tex-math></inline-formula>, determines whether an <inline-formula><tex-math id="M31">\begin{document}$ (m,n,w) $\end{document}</tex-math></inline-formula>-domination mapping exists for a domination graph with an equitable degree distribution.
Information plays a significant role in modern process industries due to the demand for flexibility and mobility in production. Therefore, it is important to preserve the privacy and security of the information exchanged and shared between partners in value chains, for instance asset chains or supply chains. Since many companies have their own technological solutions and methods for operation and control, this information is regarded as their intellectual property. For the protection of recipes, material flows, or operational and control variables during the manufacturing of products, various methods are available. These techniques include anonymization and encryption solutions. To deal with mathematical models and the computation of formulas, homomorphic encryption schemes can be applied to the data which have to be shared within a value chain. Based on the experience of previous implementations of homomorphic crypto system in different domains, the opportunities for adaptation of encryption methods in process industries are considered. This paper proposes the application of homomorphic encryption in a value chain and defines a specific protocol that enables the Paillier cryptosystem on a time series. A use case is designed for confidential information exchange between a secret owner and a value provider in a value chain. The architecture of confidentiality-preserving information sharing satisfies the zero-knowledge proof requirement and shows low similarity between original and recovered messages.
A verifiable random function (VRF in short) is a powerful pseudo-random function that provides a non-interactively public verifiable proof for the correctness of its output. Recently, VRFs have found essential applications in blockchain design, such as random beacons and proof-of-stake consensus protocols. To our knowledge, the first generation of blockchain systems used inherently inefficient proof-of-work consensuses, and the research community tried to achieve the same properties by proposing proof-of-stake schemes where resource-intensive proof-of-work is emulated by cryptographic constructions. Unfortunately, those most discussed proof-of-stake consensuses (e.g., Algorand and Ouroborous family) are not future-proof because the building blocks are secure only under the classical hard assumptions; in particular, their designs ignore the advent of quantum computing and its implications. In this paper, we propose a generic compiler to obtain the post-quantum VRF from the simple VRF solution using symmetric-key primitives (e.g., non-interactive zero-knowledge system) with an intrinsic property of quantum-secure. Our novel solution is realized via two efficient zero-knowledge systems ZKBoo and ZKB++, respectively, to validate the compiler correctness. Our proof-of-concept implementation indicates that even today, the overheads introduced by our solution are acceptable in real-world deployments. We also demonstrate potential applications of a quantum-secure VRF, such as quantum-secure decentralized random beacon and lottery-based proof of stake consensus blockchain protocol.
Abstract In this work we prove the uniqueness of solutions to the nonlocal linear equation $$L \varphi - c(x)\varphi = 0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>L</mml:mi> <mml:mi>φ</mml:mi> <mml:mo>-</mml:mo> <mml:mi>c</mml:mi> <mml:mo>(</mml:mo> <mml:mi>x</mml:mi> <mml:mo>)</mml:mo> <mml:mi>φ</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> in $$\mathbb {R}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>R</mml:mi> </mml:math> , where L is an elliptic integro-differential operator, in the presence of a positive solution or of an odd solution vanishing only at zero. As an application, we deduce the nondegeneracy of layer solutions (bounded and monotone solutions) to the semilinear problem $$L u = f(u)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>L</mml:mi> <mml:mi>u</mml:mi> <mml:mo>=</mml:mo> <mml:mi>f</mml:mi> <mml:mo>(</mml:mo> <mml:mi>u</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> in $$\mathbb {R}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>R</mml:mi> </mml:math> when the nonlinearity is of Allen–Cahn type. To our knowledge, this is the first work where such uniqueness and nondegeneracy results are proven in the nonlocal framework when the Caffarelli–Silvestre extension technique is not available. Our proofs are based on a nonlocal Liouville-type method developed by Hamel, Ros-Oton, Sire, and Valdinoci for nonlinear problems in dimension two.
The Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) in 2013-2014 was the most comprehensive analysis of anthropogenic climate change, its impacts, and potential responses. It concluded that climate change is “unequivocal” and human activities are the dominant cause. Avoidance of “dangerous” climate change will require sustained substantial reductions of emissions by mid-century and that net emissions decrease to zero before 2100. This paper describes, reviews and explains the place of tourism in AR5 and AR5’s relevance for tourism’s future, including impacts, adaptation, vulnerabilities, and mitigation. Tourism’s position in AR5 has strengthened, particularly with respect to the recognition of transboundary impacts, the sector’s contribution to climate change and its mitigation requirements. Major regional knowledge gaps persist. A lack of understanding of the integrated impacts of climate change and the effectiveness of adaptation strategies potentially hinders the development of resilient tourism operations and destinations. Uncertainties regarding tourist response to climate change impacts and mitigation policy impede predictions of tourism demand. The implications of different decarbonization pathways for the future of international tourism represent a key knowledge gap. The limited response of key tourism organizations to AR5 contributes to the risks climate change poses to the sector. Keywords: climate change; mitigation; adaptation; emissions; impacts; development Please note that the version provided here is the uncorrected proof version. For the authoritative version please go to the journal website: http://www.tandfonline.com/doi/full/10.1080/09669582.2015.1062021#.VbMDLEV30os
Abstract We introduce the probabilistic two-agent justification logic $\textsf {IPJ}$, a logic in which we can reason about agents that perform interactive proofs. In order to study the growth rate of the probabilities in $\textsf {IPJ}$, we present a new method of parametrizing $\textsf {IPJ}$ over certain negligible functions. Further, our approach leads to a new notion of zero-knowledge proofs.
For Jews of a certain age who grew up in New York during the tail end of its Jewish gastronomic heyday—in my experience, the late 1950s through the ’70s—and who dream of sizzling potato pirogen and the aroma of gorgeous cheese blintzes surrounded by generous dollops of pillow-smooth sour cream, the graphic artist Ben Katchor’s deeply personal, exhaustively researched cultural history, The Dairy Restaurant, is required reading and viewing.Fans of Katchor’s brilliant graphic archive (his achievement was recognized by a MacArthur “genius” award in 2000) have been hungering for The Dairy Restaurant to appear since the volume was announced about fifteen years ago. Katchor’s was among the first titles listed in the inaugural Nextbook Jewish Encounters Series, guided by Jonathan Rosen, a publishing venture devoted to re-thinking the range of Jewish cultural history by inviting well-known scholars and artists to explore a particular area or historical figure of their own choosing. After years of Katchor’s rummaging the archives and ruminating over the rich history of the dairy restaurant, his Jewish Encounters volume has, at last, arrived. In the words of fellow cartoonist Mark Newgarden, The Dairy Restaurant amounts to “a bountiful steam-table of history, myth, religion, biography [and autobiography], sociology, linguistics, hard data, speculation, obsession, digression, confession, eyewitness recollection and imagination” (Katchor 2020b).A Brooklyn-born walker in the city, Katchor’s Jewish soul vibrates in solidarity with New York’s early and mid-twentieth-century luftmenschen, its tribe of traveling Jews who somehow survived on the margins, doing business. Above all, Katchor is obsessed with the residues, the remnants of urban life on the threshold of vanishing. “I’m fascinated,” he explained in a 2004 interview, “by watching people disappear from the scene” (2004).A Katchor strip is immediately recognizable. Drawn in various shades of grey wash, it captures the surreal edges of the city, revealing fantastic liminal spaces inhabited by forlorn, unmoored Jewish souls, barely hanging on. Like his most famous graphic invention, the real estate photographer Julius Knipl, Katchor peers into every shadowy crevice, his eye tracking the ephemeral, quirky zones of city life, absorbing what he terms “the pleasures of urban decay.” The critic Anthony Grafton observes, Katchor “teach[es] us to see with new eyes the fragments of an older New York” (2001). “Most of New York is in my memory,” Katchor has acknowledged. Resisting the pull of nostalgia, Katchor confesses that he “has no yearning to live in the past”; he has no desire to return to a sepia-toned New York saturated with the sounds and smells of early twentieth-century East European immigrant Jews because, he claims, “The layers of history I see walking the streets of Manhattan are deep enough” (2004). Katchor’s subject, his structure of feeling, is thus the city’s subterranean history. Jewish memory flows through him; his assignment is to channel New York’s Jewish spirit, to convey, in words and drawings, its yiddishe tam: its taste, its flavors.To understand the largest cultural meanings encoded in the dairy restaurant’s genealogy, Katchor begins in the beginning (so to speak), in the “vegetarian-based,” pastoral Garden of Eden, “a defunct eating place that one can only know from memory” (25). Katchor mavens will no doubt recall his wry allusions to the paradisaical origins of a dairy world drawn in previous strips. For example, walking the city, Knipl comes upon the “Garden of Eden Cafeteria.” This ur-dairy emporium should not be confused with the legendary Garden Cafeteria (closed 1983) on the corner of Rutgers Street and East Broadway, where I. B. Singer always ordered the rice pudding (65 cents, according to the menu Katchor reproduces) and whose iconic sign is now embedded within the interior walls of the Eldridge Street Synagogue. An ad for “Golden Calf Brand Pot Cheese” appears in another panel.1 Perhaps it’s a potential (if hilariously ironic) menu item for one of the future milkhedike (milk-based) eateries along Second Avenue; or, possibly, it is Katchor’s sly prophecy to fleyshik (meat)-inclined, backsliding meat worshippers: a rebuke to those unchosen Jews who will never be able to order “pot cheese with sour cream” for 40 cents at Steinberg’s Dairy Restaurant (2270 Broadway, between 81st and 82nd street; closed 1969) in the future Promised Land of New York City, the Zion of dairy cuisine.The Dairy Restaurant thus performs a loving act of ethnic-gastronomic-institutional recuperation, the fulfillment of Katchor’s long-nourished, decades-long project to mine the layers of Jewish history sedimented in the story of this uniquely Jewish American eatery. Katchor traces the advent of dairy from its pastoral origins in Eden to the peripatetic world of traveling Jews, precursors of Knipl, who worried, while on the road, whether their meals were prepared by observant landsmen according to the rules of kashruth. “Who’s in charge of the food?” (74) was, perhaps, the most urgent question when a Jew arrived at a place to eat and rest for the night. Was the Mosaic prohibition concerning the mixing of milk and meat being observed? What could a traveling Jew safely eat without transgressing the taboo, “Do Not Seethe a Kid in Its Mother’s Milk”? (43). As it turns out, the various options (with daily specials) would eventually be inscribed on the packed vertical columns of milkhedike-based restaurant menus, huge tablets, like the ones Katchor reprints from emporiums like Rapoport’s (91–93 Second Ave.; then moved to Forest Hills; closed 1970) and Ratner’s (various locations along Second Ave.; moved to Delancey St.; closed 2002) listing “the endless possibilities of dairy eating” (143).An avid collector of New York arcana, Katchor possesses a comprehensive knowledge of the various intersecting histories relating to the dairy restaurant; his aim is to animate, through hundreds of drawings, its long-disappeared sites of memory. Katchor’s breadth of knowledge dazzles. At times, however, the sheer amount of information in this thick description can be overwhelming, its various narrative threads hard to untangle; his turns in perspective (restaurant genealogies, culinary traditions, historical actors) can induce reader whiplash.Yet we can only marvel at Katchor’s (over)flowing catalogue of anecdotes, startling factoids, and cultural contexts. In this respect Katchor’s mode of analysis recalls a famous passage in Saul Bellow—who loved the blintzes served at New York’s dairy cafés, and who makes a brief appearance in The Dairy Restaurant—from his 1956 comic novel, Seize the Day. Reflecting on the challenge of discussing mundane things with the self-styled philosophers of the Upper West Side, with whom “you had to translate and translate, explain and explain,” Bellow’s narrator observes: “If you wanted to talk about a glass of water, you had to start back with God creating the heavens and earth; the apple; Abraham; Moses and Jesus; the Middle Ages; gunpowder; the Revolution; back to Newton; up to Einstein; then war and Lenin and Hitler. After reviewing this and getting it all straight again you could proceed to talk about a glass of water” ([1956] 1976, 79).For Katchor, in order to talk about the dairy restaurant, he needs to explain a lot. Here’s a partial list, culled from the almost five hundred packed pages of The Dairy Restaurant: that Abraham, an early example of Jewish hospitality, ran the first dairy restaurant, which was blessed with a good corner location; the emergence of the restaurant in eighteenth-century France; the rise of milk spas, “Milchhallen,” and the milk cure in the nineteenth and early twentieth centuries; the 1908 “sour milk craze” in New York; a list of 29 dairy-related Jewish establishments located on the Jewish streets of Warsaw, as listed in the 1929 Business Directory of Poland (129); that Tolstoy was a visionary vegetarian who inspired Jewish radical sympathies as a “figure of the ideal ethical intellectual” (206); how “milk was covertly delivered to the Warsaw Ghetto by a pipeline” (193) and that the Emanuel Ringelblum Archives, which preserved the history of the Ghetto, were miraculously hidden in large milk cans; that many famous Yiddish actors and writers of the early twentieth century—like the modernist poets of the Di Yunge group, who frequented the Levin & Goodman Milkhiger Restaurant on East Broadway—made dairy cafés their convivial salon of choice; the Kosher Meat Wars of the early twentieth century; that scenes from Martin Ritt’s The Front (1976) were shot at Steinberg’s Dairy, and that members of the cast and crew, many of whom, like Zero Mostel and Herschel Bernardi, were blacklisted in the 1950s, convened there regularly; the differences and variations among East European cuisines and their respective restaurant locations on the Lower East Side; that the original Ratner’s on 103 Second Avenue stood next to the famed rock ‘n roll music venue the Fillmore East, where in 1969 Leonard Bernstein and Frank Zappa dined after a concert; Zappa, we’re told, sampled gefilte fish for the first time, which he apparently enjoyed.Perhaps most poignantly, at its core The Dairy Restaurant offers a topology (or perhaps a midrash, ultimately, alas, a threnody) filled with hundreds of remarkable backstories in blessed memory of long-vanished dairy restaurants, famous and obscure, organized by geographical region, by borough, and for Manhattan, by neighborhood—a granular mapping of virtually every dairy eating possibility in New York.2 For many, proof of their existence can be documented only by the ephemeral remains of matchbook covers (in this regard Katchor is grateful for “the tenacity of matchbook advertisement salesmen of that era” [232]); or extant sugar cube wrappers, modest but still material evidence of a restaurant’s existence; or via ads for restaurants buried in old Yiddish newspapers—like the one for “EatMor Dairy Restaurant” appearing in the Yidishes Tageblat in June 1919, announcing its opening on “84 Nassau St. bet. Fulton and John St. For the convenience of those who have their business or work in the neighborhood” (362). “EatMor Dairy”: a name as well as an injunction, it’s a phrase that sounds like one Katchor might have invented decades later; it may be, however, that the dairy restaurant invented Katchor.The most interesting speculative theme in The Dairy Restaurant, especially for students of Jewish American literature like myself, is Katchor’s idea about “a specifically milkhedike personality” (169), a figure who “expressed the qualities of the dairy culture” (169). Sholem Aleichem’s Tevye the Milkman is its avatar, a character who “lives in an eternal present” (177), bespeaking “modesty and humility” (86) before his Maker, yet not hesitant to argue with God’s indecipherable ways. Above all, Tevye’s hallmark, the defining quality of his “milkhedike” self, is his “ruminative” nature: modest, reflective, embodying a “milky”-ness akin to the nourishing, life-sustaining foods made from his cows. Later, in the character of Menachim Mendl, Sholem Aleichem would situate his journalist-alter ego in the popular dairy café—a “mleczarnia” in Polish—a recreated pastoral world, in Katchor’s estimate, “a paradise of pure rumination” (193).By contrast, Katchor speaks—critically—of an “appetive” self, associating this personality with meat-eating. In one telling drawing Katchor depicts a man (Katchor tends to sketch men) bent over a table in a restaurant devouring a large plate of meat. Eating strenuously, beads of sweat flying off the sides of his head, he seems driven in an act of mindless consumption, a non-stop fresser surrounded by truncated waiters’ arms pushing plates loaded with various meats at him (271). Discussing his unsavory experience of delicatessens, Katchor recalls, “The walls and windows dripped with sweat and condensation. The floors were thick with fat. . . . To counter the atmosphere of murder and death, some diners accompanied their meal with a celery-tonic soda” (426).In another drawing, Katchor shows two men, animal-like, mouths open wide, scarfing down large hot dogs at a stand advertising “100% Grade A Pure Beef/25 c large hamburger” (298–99). In the same scene we observe “A Vegetarian on Pitkin Ave” passing by. With hands clasped tightly together at his waist, he moves, anxiously, down the street, his body angling forward, his eyes focused ahead, fixed, ignoring the surrounding advertisements for “Kishke King” (“kishke” is stuffed animal intestines, a Jewish delicacy), “Hot Dogs,” “Fresh Killed,” “Blood Bank,” and “Ex-Lax Stool Softener” (298–99). We are meant, it seems clear, to interpret this tiny stretch of Brooklyn as a threatening fleyshik hell of temptation and chaos, a dairy anti-world overflowing with dark, putrid fluids.3Katchor does not investigate what might be termed the “fleyshik”-masculine character in Jewish cultural history; but the recent film Uncut Gems would be a good place to start; its opening night celebration took place, fittingly, at Katz’s Delicatessen, the temple of pastrami and corned beef worship. Applying Katchor’s theory, “fleyshik”-identified Jews act before they think; they’re tough; they eat ravenously; they are ravenous. Katchor, it appears, can’t tolerate their aggressive style, or the indigestion-producing foods they love to eat. Yet Katz’s still stands, a shrine to fleyshik power. Was the milkhedike promise of Jewish New York overcome by carnivores? Dairy, it appears, had no future in the city.4As it turns out, scenes—in effect, discourses—involving dairy foodways, nostalgia, table manners, and the rituals of Americanization abound in early Jewish American writing, especially in various Anzia Yezierska stories and in her under-read novel, Arrogant Beggar in with The Dairy Restaurant, her Katchor’s that their eating by a in the a or a of new world is Arrogant largest the with who her Lower East to the old to open a that the sounds and smells of the A about her this is this . . . This place makes of the where my to to dairy and an milkhedike structure in is always to a of and all the history of his previous back in the is of his in the new world by the For a however, his As a of served with by his he in is what I he the on the I was a In a of the of the into a of from his as a a milk on the Lower East For his memory his with history; was one of the the narrator observes, had of his In his popular Jewish foodways, in Yiddish about “a and you can A . . The was by popular The The and among his own memory of dairy when he in a Lower East for the name of his street, to return In an a of his milkhedike meals he with his as a of his of his of and As he with we a of what a dream of to to on a dairy how a milkhedike character to revealing the the of Katchor’s dairy as a mode of being with its the the end of a to his from the in the city’s the his to overcome the of his and by the with the ultimately, remains his will to the and he be in a his a and the on has been by an from the city’s then some milk and a like . . . then to and it . . . in and dream of his In dairy foods nourishing, In this respect his Jewish as another of Katchor’s the of The Dairy Restaurant the of New dairy history my of dairy deeply about this project over the decades was the appearance and atmosphere of dairy restaurants that in of Dairy Katchor offers brief but of dairy restaurants, their and some of whom he was able to while they were still We for example, about who at Steinberg’s as a in the late in he in we are told, for to of his in in a in the West of the was a figure in took his to the and a to of Steinberg’s biography the of a Jewish American story of East European origins and does Katchor on life the of Steinberg’s in 1969 with the that same of their it seems clear, has power. 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Attribute-based cryptography becomes one of the hot topics in cryptography, since it can provide fine-grained access control and good privacy. Σ-protocol is a 3-move public-coin honest verifier zero-knowledge proof protocol, and has important applications in many fields of cryptography. Firstly, combining the concept of attribute-based cryptography with the zero-knowledge proof, a notion of attribute-based Σ-protocol is introduced with its formal security model. Secondly, based on the standard Σ-protocol, the trapdoor samplable relation and the smooth secret sharing, a general construction of decentralized attribute-based Σ-protocol and corresponding scheme are proposed with the proofs of its securities. Finally, as the applications of decentralized attribute-based Σ-protocol, general constructions of decentralized attribute-based signature and decentralized attribute-based two-tier signature are presented by Fiat-Shamir transformation, respectively. Some concrete schemes are also presented. Performance analysis shows that the proposed attribute-based two-tier signature scheme has obvious advantages in both sizes and computation costs compared with existing schemes.
In traditional blockchain transactions,privacy protection is to encrypt users' sensitive information under the anonymity mechanism,and a trusted third party is involved to verify the transaction plaintext information.However,once the third party is attacked,the users' transaction information will be divulged.Furthermore,there is no truly trusted third party in a rational state.To better solve the privacy problems in blockchain transactions,and in view of issues of confidentiality verification of the tra-ders' transaction amount under the non-anonymous state,the PVC digital commitment protocol is adopted to hide the transaction amount in the commitment,and a publicly verifiable zero-knowledge proof scheme is established,so that verifiers are able to confidentially verify the legitimacy of the transaction without obtaining sensitive information from the traders.At the same time,the elliptic curve homomorphic encryption feature is used to encrypt the amount,thereby solving the problem of updating the traders' ciphertext ledger.The correctness of the proposed privacy protection scheme is verified and analyzed,and the results shows that compared with the existing schemes,the proposed scheme has the advantages of relatively low computational complexity,strong security and high efficiency.
Zero-knowledge proofs help to protect the privacy and security of blockchains by keeping the transaction information private. Bulletproofs are the state-of-the-art zero-knowledge technologies that perform confidential transactions without a trusted setup. However, Bulletproofs are still computationally inefficient to be applied in blockchain applications, and it is of great significance to parallelize Bulletproofs on GPUs. In this paper, we present a CPU-GPU collaborative framework to accelerate the inner-product arguments of Bulletproofs. To our best knowledge, it is the first time that Bulletproofs are implemented in a CPU-GPU hybrid system. The experiments show that our implementation achieves an average speedup ratio of 3.7x. The results also demonstrate that the CPU-GPU collaborative acceleration of Bulletproofs has properties of small size, high efficiency, and high scalability.
Classical cryptography has been around for a long time in the documented human history, but most classical ciphers were broken and even solved by hand. Shannon introduced the notion of perfect secrecy that formally defines confidentiality in the information-theoretic sense, which is only possible in the restricted scenarios where the message is no longer than the encryption key. The invention of public-key cryptography (the Diffie-Hellman key exchange protocol in 1976 and the RSA crypto-system in 1977) marks the birth of modern cryptography, allowing parties to exchange messages securely without sharing any secrets in advance. Furthermore, it provides computational security based on the conjectured hardness of mathematical problems such as factorization and the discrete logarithm. Public-key cryptography has found numerous applications in the Internet, financial and banking industry, and blockchains, and it plays a crucial role in protecting information security and asset safety. Unfortunately, in the 1990s, Shor proposed efficient quantum algorithms that solve number-theoretic problems, including factorization and discrete logarithms in polynomial time. Once a quantum computer of a particular scale becomes a reality, it will cause a devastating blow to the existing public-key infrastructure. To deal with such a ‘quantum crisis’, academia and industry are looking into the design, analysis and standardization of cryptographic algorithms that can resist quantum computers referred to as post-quantum cryptography (PQC). The National Institute of Standards and Technology (NIST) has been soliciting proposals for the post-quantum public-key algorithms since 2016. More recently, the Chinese Association for Cryptologic Research (CACR) held a competition on designing cryptographic algorithms whose public-key cryptography track focused on post-quantum cryptographic algorithms. Lattice-based cryptography is considered by most to be the mainstream technical route of post-quantum cryptography, which is reflected in the number of proposals (and their percentage of the total) received in the NIST PQC process. To reflect the status quo of post-quantum cryptography, we invite leading experts in this area to contribute three technical perspectives that aim to help readers understand the algorithms, the underlying basic techniques and different technical routes to achieve quantum resistance. The first perspective, presented by Lu and Zhang, introduces public-key cryptographic algorithms whose quantum security is reducible from the conjectured quantum hardness of lattice problems. In particular, they mainly focus on public-key encryption (PKE) and the key encapsulation mechanism (KEM), which are essential building blocks for securing the confidentiality of communication without pre-shared secrets. Both types of crypto-systems are solicited by the NIST PQC standardization and the CACR algorithm design competition. This perspective gives a comprehensive survey on practical lattice-based PKEs/KEMs, and their best-known quantum and classical attacks. Another important post-quantum crypto-system is digital signature, which ensures that three goals of information security are met other than confidentiality, namely, integrity, authentication and non-repudiation. The second perspective is on lattice-based signature by Lyubashevsky. In this perspective, he surveys different techniques in building lattice-based post-quantum crypto-systems, discusses the challenges in overcoming performance issues and gives us state-of-the-art digital signature schemes. In addition to ensuring the ‘static’ security of information in storage and transmission, advanced cryptographic algorithms and protocols can guarantee information security during the computation process (possibly among multiple parties), referred to as privacy-preserving computation. Cryptographic techniques involved in privacy-preserving computation include secure multi-party computation, zero-knowledge proof and fully homomorphic encryption. There is a pressing need to migrate them to the post-quantum era. The third perspective, by Yu and Xie, presents practical instantiations of these algorithms and discusses possible ways to migrate them to their quantum-resistant counterparts. To summarize, post-quantum cryptography has received widespread attention and made significant progress in recent years. Some post-quantum cryptographic algorithms, such as the lattice-based candidate, also have other advantages (e.g., computational efficiency and full homomorphism) over their classical counterparts. Lattice-based cryptography is an emerging field with high theoretical value and wide application, and we encourage young researchers to enter and explore this new and exciting field.
Ying Chen, Tianhui Zhou, Jun Zhou, Zhenfu Cao · 6 authors
Self-organizing vehicular social networks underpin many location-based services (LBS) such as those that collect and share environmental information (e.g., traffic and weather conditions) among vehicular users and the infrastructure. There are, however, security and privacy considerations in the sharing of such information, and one popular approach is to design lightweight authentication solutions for LBS. Existing approaches may suffer from limitations such as significant computational and/or storage overheads, latency and time delays, and consequently impractical for resource-constrained on-board units. In this paper, we propose an efficient privacy-preserving LBS bundle authentication scheme (hereafter referred to as SAVE) through secure redundancy filtering in self-organizing vehicular social networks. Firstly, an enhanced self-healing key distribution protocol with distributed revocation is proposed to reduce communication cost for retransmitting lost key material and resist free-riding attacks to enhance the authentication efficiency. Then, based on it, a generalized version of online/offline aggregate signature is proposed to achieve batch LBS bundle verification based on arbitrary one-way function holding the property of multiplicative homomorphism. Finally, an efficient zero-knowledge range proof based on lightweight one-way hash chain is designed to decide the redundancy of LBS bundles without disclosing vehicular users’ location privacy. Formal security proof and extensive simulation results demonstrate that our proposed SAVE achieves identity privacy, two levels of location privacy and the practicability in reality.
We propose a definition of ballot secrecy as an indistinguishability game in the computational model of cryptography. Our definition improves upon earlier definitions to ensure ballot secrecy is preserved in the presence of an adversary that controls ballot collection. We also propose a definition of ballot independence as an adaptation of an indistinguishability game for asymmetric encryption. We prove relations between our definitions. In particular, we prove ballot independence is sufficient for ballot secrecy in voting systems with zero-knowledge tallying proofs. Moreover, we prove that building systems from non-malleable asymmetric encryption schemes suffices for ballot secrecy, thereby eliminating the expense of ballot-secrecy proofs for a class of encryption-based voting systems. We demonstrate applicability of our results by analysing the Helios voting system and its mixnet variant. Our analysis reveals that Helios does not satisfy ballot secrecy in the presence of an adversary that controls ballot collection. The vulnerability cannot be detected by earlier definitions of ballot secrecy, because they do not consider such adversaries. We adopt non-malleable ballots as a fix and prove that the fixed system satisfies ballot secrecy.
The application of virtual power plants makes up for the shortcomings of new energy sources and provides ideas for the development of low-carbon power systems. As the whole society attaches importance to information security issues, user information security issues based on blockchain trading platforms have brought challenges to the development of virtual power plants. This paper proposes a virtual power plant user identity verification method based on improved zero-knowledge proof. In order to solve the problem of increased node users and increased resource consumption for identity verification, the article proposes a distributed parallel verification strategy. The test results show that the method meets the field requirements in terms of accuracy and recall of identity verification. And compared with other verification methods, it has certain performance advantages.
Zero- Knowledge Proof is a cryptographic protocol exercised to render privacy and data security by securing the identity of users and using services anonymously. It finds numerous applications; authentication is one of them. A Zero-Knowledge Proof-based authentication system is discussed in this paper. Advanced Encryption Standard (AES) and Secure Remote Password (SRP) protocol have been used to design and build the ZKP based authentication system. SRP is a broadly used Password Authenticated Key Exchange (PAKE) protocol. The proposed method overcomes several drawbacks of traditional and commonly used authentication systems such as a simple username and plaintext password-based system, multi-factor authentication system and others.
Dimitris Mouris, Charles Gouert, Nektarios Georgios Tsoutsos
The rapid growth of the globalized integrated circuit (IC) supply chain has drawn the attention of numerous malicious actors that try to exploit it for profit. One of the most prominent targets of such parties is the third-party intellectual property (3PIP) vendors and their circuit designs. With the increasing number of transactions between vendors and system integrators, the threat of IP reuse and piracy has become a significant consideration for the IC industry. What is more, the correctness of 3PIP designs should be verified before integration, imposing another challenge for 3PIP vendors since they have to prove the functionality of their designs to system integrators while protecting the privacy of the circuit implementations. To eliminate this deadlock, we utilize the cryptographic technique of “zero-knowledge proofs” to enable 3PIP vendors to convince system integrators about various functional properties of a circuit (e.g., area, power, and frequency) without disclosing its netlist (i.e., in zero-knowledge). Our approach comprises a circuit compiler that transforms arbitrary netlists into a zero knowledge-friendly format and a library of modules that provide cryptographic guarantees for various properties of the netlist while hiding the actual gates. We evaluate our method using combinational and sequential circuits from the ISCAS and ITC benchmark suites.
Physical Unclonable Functions (PUFs) and Hardware Security
Blockchain system is the novel decentralized trustworthy network and it is widely used for the digital asset management. In the bitcoin-like blockchain systems, the transactions are finished via the cryptography scripts. The user's public key hash code and address information are recorded in a locking script, and posted on the blockchain for verification. By analyzing all transaction records of an address, we can obtain the transaction behaviors of the address, including transaction frequency, number of transactions, and typical address for long-term usage. Sometimes, user privacy will be impacted according to the above analysis. To solve the problem, this paper proposes an anonymous hidden transaction model of the blockchain systems through modifying the original blockchain transaction script. In the proposed multi-layer model, the blockchain transaction system is divided into three layers. For top to bottom, they are shell account (under the public address) layer, hidden account (under the private address) layer and the user layer respectively. The hidden accounts can map to different shell account to complete the transactions. We combine the zero-knowledge proof mechanism so that the finished transaction can be verified by any user. The theoretical analysis shows that our proposed method can effectively protect transaction user information and realize truly anonymous transactions.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
After the General Data Protection Regulation (GDPR) was introduced, some organizations and big data companies shared data without conducting any privacy protection and compliance authentication, which endangered user data security, and were punished financially for this reason. This study proposes a blockchain-based GDPR compliance data sharing scheme, aiming to promote compliance with regulations and provide a tool for interaction between users and service providers to achieve data security sharing. The zero-knowledge Succinct Non-Interactive Arguments of Knowledge (zk-SNARK) algorithm is adopted for protecting data and ensure that the user’s private data can satisfy the individual requirements of the service provider without exposing user data. The proposed scheme ensures mutual authentication through the Proof of Authority consensus based on the Committee Endorsement Mechanism (CEM-PoA), and prevents nodes from doing evil using the reputation incentive mechanism. Theoretical analysis and performance comparison indicate that the scheme meets the confidentiality, availability, and other indicators. It has superiority in efficiency and privacy protection compared with other schemes.
Lattice-based non-interactive zero-knowledge proof has been widely used in one-way communication and can be effectively applied to resist quantum attacks. However, lattice-based non-interactive zero-knowledge proof schemes have long faced and paid more attention to some efficiency issues, such as proof size and verification time. In this paper, we propose the non-interactive zero-knowledge proof schemes from RLWE-based key exchange by making use of the Hash function and public-key encryption. We then show how to apply the proposed schemes to achieve the fixed proof size and rapid public verification. Compared with previous approaches, our schemes can realize better effectiveness in proof size and verification time. In addition, the proposed schemes are secure from completeness, soundness, and zero-knowledge.