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Jacob Steere‐Williams

Previous articleNext article FreeA “Menace” or a Martyr to the Public’s Health?Jacob Steere-WilliamsJacob Steere-WilliamsCollege of Charleston Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreAs a historian of public health, it strikes me that the concept of uncertainty is key to understanding pandemics. Much like past pandemics, our current public health crisis, COVID-19, is surrounded by uncertainty. Transmission rates, reinfection probabilities, testing modalities, and—perhaps topping the list right now—the role played by asymptomatic carriers are all shifting scientific questions. And as in the past, scientific uncertainty has led to the questioning of scientific expertise by the broader science-consuming public.It is no surprise, then, that in our own pandemic moment of uncertainty we have turned to past pandemics to help us navigate the present. I have been most interested in seeing the expression “Typhoid Mary” reappear in news headlines, the hashtag #TyphoidMary trend on Twitter. Given that the causative organism for the novel coronavirus can spread through asymptomatic carriers, even if we do not quite yet know the extent, a renewed interest in Typhoid Mary makes sense. The name still provokes stirring images about an inherent dichotomy in modern public health: how governments are at once charged with preserving individual civil liberties and with stopping the spread of infectious disease in the community. Not knowing who is healthy and who is sick is worrying enough; knowing that seemingly healthy individuals can unknowingly spread an infectious disease is quite another matter and has produced palpable anxiety.Judith Walzer Leavitt’s 1996 Typhoid Mary: Captive to the Public’s Health was a milestone scholarly exploration of the most notorious asymptomatic carrier in the past, Mary Mallon.1 The basic details of Mallon’s life are well known. Born in County Tyrone, Ireland, she immigrated to America in 1883 and became a cook for several prominent New York families. At some point around 1900 Mallon contracted typhoid fever, a food- and water-borne bacterial infection and one of the leading causes of death at the time. A civil engineer, George Soper, independently investigating the cause of a violent outbreak of typhoid in 1907, traced the epidemic back to the cook, Mary Mallon. He implored New York City’s health officer, Hermann Biggs, to apprehend Mallon, obtain stool, urine, and blood samples, and—if they were found positive for typhoid—isolate her. Although Mallon showed no symptoms of the disease, bacteriological tests for Salmonella typhi were positive and Mary was quarantined on North Brother Island for two years. Despite signing a legal affidavit that she would not handle food upon her release, she was discovered—again by Soper—to be the cause of a subsequent outbreak of typhoid at Sloane Maternity Hospital in 1915. Mallon was thereafter demonized by health officials and the media, constructed as a “menace to the public’s health” (p. 69) and “the most dangerous woman in America” (p. 132). She was sent back to North Brother Island, where she died in 1938.The brilliance of Leavitt’s Typhoid Mary is what today we would call its intersectional approach. Mary Mallon’s fate was shaped, Leavitt argues, at the intersections of gender, class, race, and ethnicity. In Leavitt’s hands the story twists around like a Rubik’s Cube, each chapter turning, complicating, and nuancing. The journey takes us into the perspectives of bacteriologists, public policy makers, lawyers, the media, the broader public, and Mary herself.Rereading Leavitt’s book in the time of COVID-19 reinforces the power of studying epidemics using an intersectional approach. In our own moment of uncertainty about transmission and reinfection, long-standing structures of systemic racism and health inequalities have exposed racial and ethnic minorities to much higher rates of infection and death from COVID-19. The same forces worked on Mary Mallon in the early twentieth century, first in exposing her to typhoid fever and later in American public health officials designating her—a single, female, Irish, immigrant cook—a threat to the nation’s health.Origin Stories: Why Mary? and Why Bacteriology?Uncertainty is at the heart of Leavitt’s Typhoid Mary, which seeks to understand why Mary Mallon was singled out and quarantined for over twenty years while thousands of healthy typhoid carriers roamed American streets. In the first three decades of the twentieth century, the healthy carrier presented a serious public health risk. It was the newest fad in public health, a kind of canary in the coal mine. Deaths from typhoid fever were decreasing as a result of the implementation of municipal water and sewerage projects and the safeguarding of milk supplies, but sporadic outbreaks continued. With the discovery of the healthy carrier, and the highly publicized case of Mary Mallon, public health authorities had a new way to explain ongoing outbreaks and to teach domestic sanitation and personal hygiene—what Nancy Tomes has called “the gospel of germs”—to everyday Americans, particularly immigrants.2But in practice public health officials were unsure how to solve the healthy carrier problem. What rights could be infringed upon, and what powers did local authorities have? Seeing hundreds of heavily armed protesters recently storm the capitol building in Lansing, Michigan, demanding an end to quarantine and stay-at-home orders, reminds us that government authorities are still unsure. In early twentieth-century America, health officers across the country identified and surveilled lists of healthy typhoid carriers. Some of these individuals were isolated for a short period, but most fell through the cracks and escaped oversight. Virtually none were treated like Mary Mallon. Her ethnicity, her work, and her gender served to single her out, marking her as an important case, but Leavitt argues that another reason for the attention she received is that she was the “first” healthy carrier identified in America. Recent scholarship, particularly by Christoph Gradmann and Richard McKay, has underscored how such origin stories can turn toxic and serve class-based and race-based agendas.3To address the uncertainty of the healthy carrier—for typhoid in the early twentieth century and for COVID-19 today—we have turned to laboratory testing. And here too Leavitt’s account can help us understand our current pandemic: how conflicts of scientific expertise shape pandemic responses and how laboratory practices reveal deeper social structures. Take just one example from the book: the 1909 court decision that kept Mary medically imprisoned on North Brother Island. From March 1907 to June 1909, the New York City health department collected and analyzed 163 fecal specimens from her—more than one per week. But their bacteriological results were inconclusive. So often were the tests for Salmonella typhi negative, and so bent was Mallon on disproving the expertise of the city laboratory, that she sought out an independent laboratory, Ferguson Laboratories, to analyze her urine and feces. In all of his bacteriological tests George Ferguson found no positive typhoid cultures. Despite the conflicting evidence, in 1909 the judge ruled in favor of the city health officials, responding to what I have termed a “conflict of analysis”: in a moment when scientific experts disagree on methodology or results, factors of race, class, and gender shape how courts decide routine cases. Given Christopher Hamlin’s recent work on fin-de-siècle bacteriology, I am left wanting more on the differing bacteriological analyses and wondering how representative Mary’s case was within bacteriological circles at the time.4 In my own research on debates over late nineteenth-century legal cases pertaining to typhoid and food adulteration, such conflicts in scientific practice were the norm, not the exception. In the time of COVID-19, conflicts over testing, and reports of inaccurate tests, are shaping how we experience the pandemic and how our governments respond to it. Both for Mary Mallon’s time and now, the material culture of surveillance through testing is critical and deserves closer scrutiny.In important ways, though, scholarship on the germ theory and laboratory bacteriology has shifted since Leavitt wrote Typhoid Mary. Baked into Leavitt’s account is the idea that the bacteriological revolution represented a sharp epistemological break from older theories of disease causation and public health practice.5 A new faith in the laboratory fueled a “new” public health bent on identifying and isolating individuals, not cleansing environments. Leavitt writes that “bacteriological laboratories with their microbe-identifying capabilities became the single most crucial tool in identifying the people and the problems to which health departments should attend” (p. 26).Scholarship that followed Leavitt’s book, such as the work of Michael Worboys, has shown that debates about germs raged into the early twentieth century.6 Skepticism about the authority and expertise of laboratory bacteriology continued, we now know, well after the German hygienist Max von Pettenkofer, in the ultimate act of defiance of Robert Koch’s laboratory discovery of Vibrio cholerae, swallowed a cholera broth in 1892. Decentering the power of the bacteriological laboratory opens up at least two important ways to rethink the story of Typhoid Mary in the time of COVID-19. The first is to see conflicts in laboratory testing as key sites of knowledge production and powerful tools to politicize the science of pandemics. Today, for example, decentering the COVID-19 laboratory might help us better see preexisting health-care disparities as a driver of differential morbidity and mortality and encourage us to redouble public health efforts focused on preventable deaths that result from social determinants of health. The second is to see the field-based practices of epidemiology as deeply related to the laboratory-based practices of bacteriology.Recent research suggests that we might view the story of Typhoid Mary and the asymptomatic carrier not solely through the lens of laboratory bacteriology but also through the lens of epidemiology. In my own work, I have found that epidemiological approaches dominated thinking about typhoid through the first two decades of the twentieth century. Epidemiological practices were spatial, statistical, and environmental, but epidemiologists also were philosophically committed to the idea that typhoid was a specific disease spread via media such as food, water, and people. Experiences with healthy carriers like Mary Mallon were part of a longer gestation of epidemiological practice. Often epidemiologists claimed that they did not need the expertise of the laboratory to provide proof or to shoulder the burden of identifying an index case, and laboratory evidence was often seen instead as back-end scientific proof. We might, for example, see George Soper’s identification of Mary Mallon as the cause of two typhoid outbreaks within the longer history of epidemiological practice. Soper self-identified as a “thoroughly trained and experienced epidemic fighter who had seen service in the laboratory and the field” (p. 103). Leavitt calls him an “engineer epidemiologist” (p. 109), but I wonder how that label stacked up against contemporary Anglo-American actor categories. While Soper may have practiced epidemiological methods, did he identify as an epidemiologist? Was he part of what Thomas Gieryn calls disciplinary “boundary-work”? In other words, how representative was Soper’s brand of epidemiological practice? My book The Filth Disease, on epidemiological practice related to typhoid in Britain, sheds some important light on this question, but we still don’t have a comparable American work.7 Such a reframing of the story forces us to ask different questions about the history of epidemiology and bacteriology and reminds us today, in the middle of a pandemic, to think through the reliability of COVID-19 tests alongside the reliability of epidemiological maps and statistics.One criticism I have of Leavitt’s book that helps us think about COVID-19 today is how stable typhoid itself appears throughout Typhoid Mary. I have long struggled to make sense of the epistemological problem that what we today call typhoid fever does not neatly map onto the way late nineteenth- and early twentieth-century observers used the word “typhoid.” Anne Hardy’s 2015 Salmonella Infections, Networks of Power, and Public Health in Britain, 1880–1975, goes some way in clarifying how, in the early twentieth century, what had long been called typhoid was split into a number of distinct subcategories. “Typhoid” came to mean a single disease caused by Salmonella typhi, but bacteriologists also learned that there were subcategories of similar diseases in the Salmonella family, such as paratyphoid A and B.8 Typhoid was a disease in motion, in other words, not a stable target. There is a kind of epistemological certainty in Typhoid Mary about the stability of disease categories that looms particularly large as we confront COVID-19. Early in the pandemic there were reports of ongoing mutations, and the novel coronavirus that causes COVID-19 is—maybe not unlike typhoid in the early twentieth century—a disease in motion.I have been teaching the story of Mary Mallon for over a decade, largely through the lens of Leavitt’s multiple frameworks and intersectional approach. Students often comment in their course evaluations that this was the topic that resonated with them the most all semester. I suspect that, going forward, because of COVID-19 Typhoid Mary will become even more important in our classroom discussions about the complexities of public health, about naming and blaming as part of the fabric of epidemics, and, above all, about how science functions in moments of uncertainty.NotesJacob Steere-Williams is Associate Professor of History at the College of Charleston. His research focuses on the history of infectious disease, public health, and biomedicine. He is the author of The Filth Disease: Typhoid Fever and the Practices of Epidemiology in Victorian England (Rochester, 2020). College of Charleston, 66 George Street, Charleston, South Carolina 29424, USA; [email protected].Acknowledgments. I would like to thank Nathan Crowe for reading a draft of this essay.1 Judith Walzer Leavitt, Typhoid Mary: Captive to the Public’s Health (Boston: Beacon, 1996). Subsequent references to this work are indicated in the text by page number.2 Nancy Tomes, The Gospel of Germs: Men, Women, and the Microbe in American Life (Cambridge, Mass.: Harvard Univ. Press, 1998).3 Christoph Gradmann, Laboratory Disease: Robert Koch’s Medical Bacteriology (Baltimore: Johns Hopkins Univ. Press, 2009); and Richard McKay, Patient Zero and the Making of the AIDS Epidemic (Chicago: Univ. Chicago Press, 2017).4 Jacob Steere-Williams, “A Conflict of Analysis: Analytical Chemistry and Milk Adulteration in Victorian Britain,” Ambix, 2014, 61:279–298; and Christopher Hamlin, “Bacteriology as Cultural System: Analysis and Its Discontents,” History of Science, 2011, 49:269–298.5 She explored the topic in a 1992 Isis article: Judith Walzer Leavitt, “‘Typhoid Mary’ Strikes Back: Bacteriological Theory and Practice in Early Twentieth-Century Public Health,” Isis, 1992, 83:608–629.6 Michael Worboys, Spreading Germs: Disease Theories and Medical Practice in Britain, 1865–1900 (New York: Cambridge Univ. Press, 2000).7 Thomas F. Gieryn, Cultural Boundaries of Science: Credibility on the Line (Chicago: Univ. Chicago Press, 1999); and Jacob Steere-Williams, The Filth Disease: Typhoid Fever and the Practices of Epidemiology in Victorian England (Rochester, N.Y.: Univ. Rochester Press, 2020).8 Anne Hardy, Salmonella Infections, Networks of Knowledge, and Public Health in Britain, 1880–1975 (Oxford: Oxford Univ. Press, 2015). Previous articleNext article DetailsFiguresReferencesCited by Isis Volume 111, Number 4December 2020 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/712254 Views: 1660 © 2020 by The History of Science Society. All rights reserved.PDF download Crossref reports no articles citing this article.

Xiu‐Shuang Xing, Cai Sun, Lu Liu, Ming‐Sheng Wang · 5 authors

Open AccessCCS ChemistryRESEARCH ARTICLE1 Nov 2021Light-Responsive Proton Conductor: Record High Gain of Proton Conductivity Achieved by Photoinduced Electron-Transfer Strategy Xiu-Shuang Xing†, Cai Sun†, Lu Liu, Ming-Sheng Wang and Guo-Cong Guo Xiu-Shuang Xing† State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 Henan Key Laboratory of New Optoelectronic Functional Materials, College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455000 †X.-S. Xing and C. Sun contributed equally to this work.Google Scholar More articles by this author , Cai Sun† State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108 †X.-S. Xing and C. Sun contributed equally to this work.Google Scholar More articles by this author , Lu Liu State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 Google Scholar More articles by this author , Ming-Sheng Wang *Corresponding author: E-mail Address: [email protected] State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108 Google Scholar More articles by this author and Guo-Cong Guo State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108 Google Scholar More articles by this author https://doi.org/10.31635/ccschem.021.202000610 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Light-responsive proton conductors might find applications in both traditional fields (fuel cells, chemical sensors, bio-ionic functions, etc.) and modern high-speed switchable smart systems (Internet of things, robotics, etc.). Previous synthetic methods resulted in low switching contrasts (<two times) or they tended to be limited significantly in solid matrixes due to large structural changes. The photoinduced electron-transfer (PIET) method avoids the influence of stereo space in solid matrixes and capable of achieving high switching contrasts. For the first time, we applied the PIET strategy to design light-responsive proton conductors to achieve the hitherto largest gain of proton conductivity (ca. 54 times) for light-responsive proton conductors in one crystalline photochromic viologen-based H-bonded supramolecule. The weakening of hydrogen-bonding interactions in the proton-transport path after PIET accounted for an increased proton conductivity. These findings would inspire the exploration of photon conductors that display higher proton conductivities or switchable smart systems with high contrasts. Download figure Download PowerPoint Introduction Proton conductors attract extensive attention for applications in fuel cells, chemical sensors, and bio-ionic functions.1–3 Current research endeavors mainly focus on achieving high conductivity in crystalline materials with H-bonded networks such as coordination polymers (CPs) and metal–organic frameworks (MOFs) by encapsulation of proton carriers, pore surface functionalization, defect introduction, and so on.4–12 However, due to the development and stimulation of high-tech industries such as the Internet of things and robotics, regular proton conductors cannot meet the new stimuli-responsive smart systems’ requirements. The light mode has advantages of noninvasiveness, high spatial resolution, and easy and quick modulation, and thus, light-responsive proton conductors and related systems have attracted close attention. For example, Wen et al.13 fabricated a bio-inspired photoelectric conversion system based on a cross-membrane pump of proton originating from the light-driven dissociation of a photoacid; the Kitagawa group14 provided a photoacid (pyranine)-doping strategy to increase mobile acidic protons and local defects upon irradiation, and thus, realized the enhancement of proton conductivity (contrast: ca. one time) in a melted CP. Additionally, the Heinke group observed a photoinduced decrease of proton conductivity due to an enhancement of hydrogen-bonding interactions between framework and proton-conducting guests when photochromic azobenzene (contrast: ca. one time)15 or spiropyran (contrast: ca. 100 times)16 moieties were anchored to the linker of a MOF. Further, very recently, Chen’s group17 achieved a dramatic decrease in proton conductivity (contrast: ca. 10,000 times) by encapsulating sulfonated spiropyran into MOF pores, where photoinduced ring open of photochromic spiropyran blocked hydrogen-bonding network and consequently reduced proton-conduction mobility. These studies explored two applicable methods to modify proton conductivities successfully: (1) light-driven dissociation of protons and (2) photoisomerization of photochromic molecules. The former had few stereo space requirements in the solid matrixes but usually resulted in low switching contrasts (<two times). The latter might yield high switching contrasts but are significantly limited in solid matrixes due to extensive structural changes. Thus, it is highly desirable to explore a new method that can combine the advantages of the two known methods. Additionally, high-contrast enhancement efforts of proton conductivity after light irradiation, instead of weakening the process, are appealing for a real application; however, effective strategies to this aim are also lacking. Electrons and protons often work together in natural photosynthetic and enzymatic systems.18,19 Besides, electron transfer usually results in minor structural change.20,21 Inspired by these points, we presume that electron transfer or electron redistribution in a material system could affect the performance of proton conduction significantly and is well adapted to a solid matrix. Suppose one crystalline compound with an infinite hydrogen-bonding network is able to undergo photoinduced electron transfer (PIET), it can act as a good proof-of-concept model to verify our idea and further explore the regulated mechanism involving the interrelationship of electron transfer and proton transport. Diprotonated 4,4′-bipyridinium (a typical viologen; abbreviated as H2V hereafter) can accept one electron from an electron donor to yield a stable radical and generate a photochromic phenomenon after irradiation.22 The existence of N–H bonds in H2V offers an opportunity to construct a hydrogen-bonding network. If free or coordinated water molecules and/or hydroxyl groups are further included, then the formation of an H-bonded supramolecule with an infinite hydrogen-bonding network is highly possible. Furthermore, crystalline species particularly favor the study of internal structural information. Therefore, crystalline compounds with “H2V,” “free or coordinated water” and/or “hydroxyl” groups are suitable proof-of-concept models to understand the relationship between the PIET process and proton conduction. Experimental Methods Materials and instruments All chemicals of analytical grade were obtained from commercially available sources and used as received without further purification. Powder X-ray diffraction (PXRD) patterns at room temperature were acquired on a Rigaku Miniflex II Desktop X-ray diffractometer (Tokyo, Japan) using Cu Kα radiation (λ = 1.540598 Å) at 40 kV and 40 mA ranging from 5° to 50°. A simulated PXRD pattern was obtained from the Mercury Version 2020.1 software ( http://www.ccdc.cam.ac.uk/products/mercury). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis experiments were carried out on a Mettler TOLEDO simultaneous TGA/DSC apparatus (Zurich, Switzerland) in N2, heating the sample in an Al2O3 crucible at a heating rate of 10 K·min−1. Fourier transform infrared (FT-IR) spectra were recorded on a PerkinElmer Spectrum One FT-IR spectrometer (Waltham, MA) using KCl pellets in the 4000–400 cm−1 range. Electron absorption spectra were measured at room temperature on a PerkinElmer Lambda 900 UV/vis/near-infrared (NIR) spectrophotometer (Waltham, MA) equipped with an integrating sphere and BaSO4 as a reference. Electron paramagnetic resonance (ESR) spectra were recorded on a Bruker-BioSpin ER-420 spectrometer (Rheinstetten, Germany) with a 100 kHz magnetic field in the X band at room temperature. Synthesis of {(H2V)[Ge(ox)2(OH)2]}·2H2O ( 1; ox = oxalate) Compound 1 was synthesized, as described previously.23 The crystal samples for all testing and characterizations were carefully picked with the aid of a microscope, checking their phase purity by PXRD ( Supporting Information Figure S1). Proton conductivity measurements Proton conductivity measurements were performed using a quasi-four-electrode alternating current (AC) impedance technique with a Solartron 1260 impedance/gain-phase analyzer. Our single-crystal measurements revealed the single-crystal shape as a triangular prism, wherein the cross-section area sizes and the length were 0.157 × 0.270 mm2 and 0.350 mm, respectively. Gold wires were connected to both ends of the longer axis of each crystal. The single crystal was measured at frequencies ranging from 107 to 1 Hz as the temperatures were varied from 303 to 323 K and the relative humidity (RH) was 95%. The resistances of the crystalline samples were deduced with the operation of a “fit cycle” from the Debye semicircle in the Nyquist plot. Computational approaches Projected band structure The calculation was based on density functional theory (DFT) in conjunction with the projector augmented wave (PAW) potential, which is implemented in the Vienna ab initio Simulation Package (VASP).24,25 The Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional with an optB86b-vdW correction was used, considering the dispersion interaction between neighboring organic components.26 Single-crystal X-ray diffraction data of 1 were used to build the calculation model. Single-point energy was calculated using plane-wave cutoff energy of 400 eV and a 3 × 3 × 2 Monkhorst–Pack grid of k-points. The dipole moment of a fragment and charge decomposition analysis The calculations indicated above were derived using the Gaussian 09 D01 version and Multiwfn software.27–29 As shown in Supporting Information Figure S8, the molecular model was taken from the single-crystal structure of 1. H atoms in the Ge complex and the water molecule were optimized at the M06-2X/def2-svp level, while other atoms remained unchanged. The dipole moment of a fragment (F) based on the Hirshfeld weighting function given by the equation: D F = ∑ A ∈ F [ Z A R A − ∫ [ ω A ( r ) ρ ( r ) ] r d r ] where A is the atomic index in F, ZA, RA, and ωA(r) are nuclear charge, position, and atomic weighting function of atom A, respectively.28 The charges were set as −2 and −1 for the Ge complex in initial and colored states. The charge decomposition analysis (CDA) proposed by Dapprich and Frenking is used to provide a deep insight into how charges are transferred within fragments in a complex to achieve charge equilibrium.27 In CDA, the fragment orbital (FO) denotes the molecular orbital (MO) of a fragment in its isolated state. Three terms are defined as follows: d i = ∑ m ∈ A occ ∑ n ∈ B vir η i C m , i C n , i S m , n b i = ∑ m ∈ A vir ∑ n ∈ B occ η i C m , i C n , i S m , n r i = ∑ m ∈ A occ ∑ n ∈ B occ η i C m , i C n , i S m , n where i and η are index and occupation number of MO of complex, respectively. S m , n = ∫ f m ( r ) f n ( r ) d r is an overlap integral between FO m and FO n. Cm,i denotes the coefficient of FO m in MO i of the complex. The superscript “vir” and “occ” mean virtual (viz. unoccupied) and occupied, respectively. The term di denotes the amount of electron donated from fragment A to B via MO i of the complex; similarly, the term bi denotes the electron back donated from B to A. The term r reveals closed-shell interaction between two occupied FOs in different fragments; a positive value of ri means that owing to MO i, the electrons of the two fragments are accumulated in their overlap region and shows bonding character, while a negative value indicates that the electrons are depleted from the overlap region, and thus, reflect an electron repulsive effect. In the initial state, the charges for the Ge complex, water, and H2V were set as −2, 0, and +2, respectively, while those in the colored state were set as −1, 0, and +1, respectively. The spin multiplicities were set as 1 and 3 for initial and colored states of the model complex, respectively. Results and Discussion Through screening of the Cambridge Crystallographic Data Center (CCDC) database, 185 structures with “H2V,” “free or water,” and/or “hydroxyl” were found ( Supporting Information Figures S2 and S3). From these structures, compound 123 was chosen as a proof-of-concept model, considering its well-resolved crystal structure, the presence of an infinite hydrogen-bonding network, and potential electron-transfer photochromic property. Figure 1 shows that compound 1 was constructed by H2V ions, Ge complexes, and free water molecules through intermolecular hydrogen bonds and van der Waals interactions. In the Ge complex, each Ge atom was coordinated by six oxygen atoms from two ox ligands and two hydroxyl groups to form a distorted octahedron. The coordinated O(9) hydroxyl groups and free O(2W) water molecules form an infinite hydrogen-bonding network along a direction that provides 1D proton-transporting channels. Notably, the hydrogen atoms of the O(9) hydroxyl group and the O(2W) water molecule were found to be disordered over two distinct crystallographic positions [H(4W) and H(5W) for the water molecule, and H(9A) and H(9B) for the hydroxyl group].23 This disorder means that the active O(9) hydroxyl group and the O(2W) water molecule can reorient themselves readily to make the oxygen atoms have a proper angle to accept hydrogen atoms for proton transport through the Grotthuss mechanism.30,31 Moreover, it has been reported that the electron on the oxygen atoms of an ox could transfer to H2V after irradiation in a photochromic process.32 The nearest distance between the ox oxygen atom and the H2V nitrogen atom in 1 was about 2.811(3) Å, which met the distance of typical PIET occurrence.33,34 Therefore, compound 1 has a high probability of exhibiting electron-transfer photochromic properties. Figure 1 | Crystal structure of 1 showing an infinite hydrogen-bonding network along the a axis. Hydrogen bonds: O(2W)–H(4W)⋯O(2W, symmetry codes: −x, 1−y, −z), dO(2W)⋯O(2W) = 2.738(3) Å, ∠[O(2W)–H(4W)⋯O(2W)] = 161(4)°; O(9)–H(9B)⋯O(2W), dO(9)⋯O(2W) = 3.188(3) Å, ∠[O(9)–H(9B)⋯O(2W)] = 119(3)°; O(9)–H(9B)⋯O(9, symmetry codes: 1−x, 1−y, −z), dO(9)⋯O(9) = 3.004(4) Å, ∠[O(9)–H(9B)⋯O(9)] = 133(5)°; O(9)–H(9A)⋯O(2W, symmetry codes: 1−x, 1−y, −z), dO(9)⋯O(2W) = 2.800(3) Å, ∠[O(9)–H(9A)⋯O(2W)] = 161(6)°. Partial disordered H atoms are drawn in light green. The green arrows indicate the proton transport channel by the Grotthuss mechanism. Download figure Download PowerPoint Our experimental data could well demonstrate the above speculation. Upon continuous irradiation by a diode-pumped solid-state (DPSS) laser (355 nm, 369 mW·cm−1) for only 30 s under ambient conditions, the colorless as-synthesized crystalline sample ( 1A) underwent a rapid, apparent color change to a purple sample ( 1B) (Figure 2a). No generation of prominent new peaks or disappearance of old peaks was observed in the PXRD pattern ( Supporting Information Figure S1), indicating no evident structural change during the coloration process. Furthermore, TGA curves before and after the coloration also displayed no noticeable difference, which suggested that the free water molecules were not lost after coloration ( Supporting Information Figure S5). These results excluded the occurrence of photoinduced dissociation after the coloration. Additionally, two characteristic electron absorption bands of viologen radicals35 appeared around 386 and 596 nm after the coloration (Figure 2c). Time-dependent absorption data indicated that the coloration process occurred rapidly and reached saturation after 2 min of irradiation. The coloration–decoloration process for 1 could be cycled at least four times ( Supporting Information Figure S6), revealing its reversible photochromism character.36 An EPR study revealed no signal for 1A, but a strong, sharp single-line signal at g = 2.0025 for 1B (Figure 2b). Both electron absorption and EPR data demonstrate the occurrence of a PIET process and the formation of H2V radicals after coloration. We confirmed the electron donor by calculating the projected band structure of 1. As illustrated in Figure 2d, the electronic states near the valence band maximum (VBM) were mainly dominated by an ox, while the conduction band minimum (CBM) was exclusively contributed by H2V. These features indicated that ox and H2V were the electron donor and acceptor, respectively. This deduction was consistent with the previous discovery in the literature that ox is an effective electron donor.32 The 1B sample could be bleached by allowing to stand in the dark in air, but complete bleaching required 2 days, as monitored by the EPR study (Figures 2a and 2b). Figure 2 | Photochromism of 1: reversible color change (a) and EPR spectra (b) in a cycle (1A, as-synthesized sample; 1B, colored sample; decolored, color-bleached sample). (c) Time-dependent electron absorption spectra upon irradiation. (d) Projected band structure with the Fermi level was set to zero by default. Download figure Download PowerPoint Proton conductivities (σ) of a single crystal of 1 were investigated by impedance spectroscopy using silver paste as electrodes with resistance extracted by fitting the corresponding Nyquist plot. As shown in Figure 3a, the Nyquist plot impedance data on the 95% RH at 303 K showed that the 1A sample has a σ value of 2.83 × 10−5 S·cm−1. After irradiation for 2 min by the DPSS laser to produce the 1B the σ value increased by about 54 times to × S·cm−1. This is the hitherto largest for light-responsive proton Thus, the above results confirmed that a light-responsive proton could be by the PIET Figure 3 | (a) Nyquist plot of the impedance of 1A and 1B under 303 K and 95% an of (b) proton conductivities of 1A and 1B at 95% of the single-crystal samples Download figure Download PowerPoint gain insight into the electron transfer an increase in proton proton conductivities were TGA revealed that compound 1 could be stable to this the free water molecules to ( Supporting Information Figure 95% the σ of 1A and 1B increased from 2.83 × 10−5 to × and from × to × respectively, with the temperature from 303 to 323 K (Figure The = based on the along with the has often been applied to the proton conduction in The calculated energy of 1A and 1B are around and (Figure and Supporting Information Figure The decrease of after irradiation indicated a in the proton conduction to an increase in the σ further understand the for increased proton conduction after irradiation FT-IR spectra were recorded (Figure As the irradiation the relative of around cm−1 for and groups while the of peaks remained unchanged. 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Download figure Download PowerPoint provides a insight into the electron influence on proton conduction from an electronic structural As shown in Figure the of orbital the overlap region between the hydroxyl group and the water molecule with a large positive r value which indicated a bonding In a in the overlap region in orbital with a large negative r value an electron repulsive (Figure Supporting Information S2 and and Figure The typical bonding and the hydrogen-bonding relationship within the hydroxyl group and water the hydrogen-bonding relationship mainly contributed to charge transfer between the Ge complex and water As shown in the electrons were transferred from the Ge complex to the water molecule due to the corresponding complex orbital This is in with our chemical in that the hydroxyl atom provided electrons to form a hydrogen with the proton in the water molecule, to the formation The decrease in from to between the Ge complex and the water molecule after coloration resulted in hydrogen-bonding the H atoms in the water molecule high and increased proton 1 | Results for a of One Ge and One in 1 d b r state state The term d denotes the number of electrons donated from the Ge complex to the water The term b denotes the electrons donated back from the water molecule to the Ge complex. The term that the Ge complex provides its electrons from occupied FOs to virtual FOs of the water The term r reveals closed-shell interaction between two occupied FOs in different We have shown in a first to modify proton conduction by the PIET Through functional structural we were able to one proof-of-concept crystalline photochromic viologen-based H-bonded supramolecule from the For a real high-contrast enhancement of proton conductivity after light irradiation is highly the of our only one known has shown proton conductivity upon irradiation and the observed of ca. one time, which is In this the proton conductivity for the proof-of-concept compound increased to ca. 54 times after a for light-responsive proton The increased proton conductivity was derived from a decrease in the energy of the proton transport by the weakening of the hydrogen-bonding interaction after A of the relationship between the electron-transfer process and proton conduction and the of high for the PIET method inspire the exploration of photon conductors with higher proton conductivities or switchable smart systems with high contrasts. Supporting Information Supporting Information is available and PXRD screening and TGA impedance the dipole moment of a and of is no of to Information This work was by the Science of and the Research of the Chinese Academy of and and the Key Research of Chinese Academy of The for on the of proton conductivity. 1. in Proton for and Google Scholar A. and and Google Scholar Kitagawa with High Proton Google Scholar as Proton and Google Scholar Kitagawa to Proton Conductivity in a Google Scholar Wang in and Simulation Google Scholar Wang with a High of for Proton Google Scholar Wang Google Scholar and Google Scholar Google Scholar

우청원, 이정우, 손수아

The demand for research data sharing and utilization increases. As digital technology develops, research data production and accumulation speed increases, and as convergence research and joint research increase worldwide, demand for sharing and utilization of research data increases. Although there is a research data platform, it is not well shared and utilized. Attempts to solve existing problems increase by incorporating blockchain into research data platforms. Blockchain has been attracting attention as a key technology of the fourth industrial revolution, and the introduction of blockchain to ensure data transparency and integrity in untacted services, which have recently been drawing attention due to Covid-19. The purpose of this study is to identify the areas where blockchain can contribute to sharing and utilizing research data, and to present a plan to build a blockchain-based research data platform. We propose five methods for building blockchain-based research data platforms. First, operators set the purpose and scope of the demand-based research data platform. Existing research data platforms did not reflect different demands by the research field. 1) Demand discovery, 2) demand clarification and typification, and 3) selection of target research field are necessary for determining Blockchain-based research data platform purpose and scope. Incentive structures must be in place to clearly distinguish the roles of the public from the private sector in the research data platform and to allow the private sector to participate in the public research data platform. Second, considering the characteristics of blockchain, application areas should be selected first and the operating system should be prepared. There are issues related to sharing and utilizing research data that are difficult to solve with blockchain, such as difficulty in collecting research data and lack of standardized research data. The blockchain implementation area should be selected based on 1) the possibility of research data collection, 2) degree of standardization, 3) capacity, and production speed. Blockchain specialized data curation that can manage research data quality is needed. Third, the possibility of implementing blockchain technology should be considered. For sharing and utilizing research data, specific blockchain technologies or services should be identified. It can be used while protecting personal information through DID and zero-knowledge proof. Cloud-based distributed storage technology enables storing and transmitting large amounts of research data. Comparison of hash values can fundamentally prevent the falsification of research data. Smart contracts can reduce sharing costs and support an incentive system. Fourth, social acceptability should be expanded by improving perceived usefulness and perceived ease of use. The social acceptability of blockchain-based research data platforms is low. It is necessary to develop services that are differentiated from existing platforms and continue to develop technologies until the number of users reaches critical mass. UX/UI development is needed to increase usability. Lastly, it is necessary to come up with measures to support the development, distribution, and management of blockchain services. It is difficult for small and medium-sized companies to cover the cost of building blockchain services. Public blockchain infrastructure support services are needed so that companies or institutions can develop, distribute, and manage blockchain services. For example, China Blockchain Service Network (BSN) supports local Internet networks and cloud services so that companies or institutions can develop standardized blockchain services.

Nathan Martindale, Scott Stewart, Mark Adams, Greg Westphal

In international nuclear safeguards, the International Atomic Energy Agency (IAEA) is tasked with inspecting and verifying nuclear facilities and their activities. Data analytics and machine learning to support inspections require large amounts of data that nuclear facility operators may consider proprietary or sensitive, so the IAEA may not have full access. Allowing computation over private data without compromising its security therefore has value for safeguards inspections and analysis. Privacy-preserving machine learning (PPML) consists of security-focused techniques that allow data analytics and machine learning algorithms to run on sensitive data without revealing it. This includes ideas like homomorphic encryption (HE), secure multiparty computation (SMPC), and secure enclaves. HE allows algorithms and mathematical operations to be conducted directly on the encrypted data instead of first decrypting it. With SMPC, multiple entities collaboratively compute over distributed data such that no party is able to directly view any others’ original data. Secure enclaves allow computation to take place in a separate and heavily blocked-off section of a CPU. Techniques like these allow for several potential use cases in which the security of data is essential. With SMPC, machine learning models can be trained over the input data from multiple entities, resulting in a model that all users can benefit from without leaking the input data from any particular entity. With SMPC or a zero-knowledge proof (ZKP), an algorithm returning some single answer or truth value can be run on someone else’s data without ever needing to see that data, potentially allowing for verification or proof of some underlying question. HE can allow for outsourcing computation on data to a hostile or untrusted environment. Although most of the research in this field resides within the health and financial domains, tools from PPML may have similar applications in nuclear safeguards. Allowing the IAEA to compute over proprietary information, such as process models and raw sensor data using PPML techniques, provides the baseline for running complex analytics without needing direct unencrypted access to the underlying data, maintaining its privacy. Important limitations to consider for these techniques include the efficiency and level of security required. The security of HE and SMPC come at the cost of speed—the significant amount of overhead means that algorithms implemented in these protocols and encryption schemes are slower than when run on plaintext. Additionally, several important parameters determine what techniques or protocols are used based on the security requirements. SMPC protocols may need to be selected for resistance against a party that attempts to deviate from the protocol to distort the result or gain access to additional information, and a protocol secure against these attacks may further increase the overhead of the algorithm.

Ahmad Alsharif, Mahmoud Nabil

The unprecedented growth of decentralized technologies and the abundance of healthcare data creates numerous opportunities for the digital healthcare industry and poses major challenges for data security. In this paper, we propose a novel decentralized blockchain-based medical data marketplace in which medical record sellers can sell their data to interested buyers, e.g., pharmaceutical corporations. Sellers use a smart contract to exchange their records with buyers for a digital currency. In our model, sellers can enforce flexible access control policy on the encrypted records while allowing the buyers to verify the correctness of the encrypted records without revealing any information about the records using the developed zk-SNARK protocol. In addition, sellers acquire a proof-of-delivery to redeem buyers' contingent payments by exchanging a record access key for a buyer signature using the developed trustless zero-knowledge contingent payment protocol. Our security analysis proves that our model is secure against malicious behaviors of both dishonest sellers/buyers. Performance evaluation indicates that the GAS cost on Etherume blockchain and the computational cost of the cryptographic operations are low.

Shunrong Jiang, Xiaoyan Zhang, Jinpeng Li, Hao Yue · 5 authors

The large-scale integration of distributed energy resources has resulted in surgical changes in energy trading systems. Traditional centralized trading systems suffer from high management cost and low efficiency. The recent advance of blockchain technology has enabled the invention of distributed energy trading systems, which can overcome the limitations of centralized trading systems. However, the distributed energy trading systems also bring new security and privacy challenges. For instance, transactions on blockchain are publicly visible which can lead to privacy leakage of trading information. Moreover, user privacy can also be leaked during verification of the aggregated energy trading result. In this paper, we propose a privacy-preserving energy trading scheme based on blockchain to meet the security requirements for distributed energy trading. We adopt a stealth transmission approach based on blockchain to ensure data privacy and break the linkage between consumers and providers in the energy trading process. We also use the non-interactive zero-knowledge proof technology to achieve privacy-preserving and trustworthy trading result verification. Security analysis and evaluation results have demonstrated that the proposed scheme can effectively protect the data privacy for distributed energy trading systems.

Ahmed Al Guqhaiman, Oluwatobi Akanbi, Amer Aljaedi, C. Edward Chow

Underwater Wireless Sensor Networks (UWSNs) are liable to malicious attacks due to limited bandwidth, limited power, high propagation delay, path loss, and variable speed. The major differences between UWSNs and Terrestrial Wireless Sensor Networks (TWSNs) necessitate a new mechanism to secure UWSNs. The existing Media Access Control (MAC) and routing protocols have addressed the network performance of UWSNs, but are vulnerable to several attacks. The secure MAC and routing protocols must exist to detect Sybil, Blackhole, Wormhole, Hello Flooding, Acknowledgment Spoofing, Selective Forwarding, Sinkhole, and Exhaustion attacks. These attacks can disrupt or disable the network connection. Hence, these attacks can degrade the network performance and total loss can be catastrophic in some applications, like monitoring oil/gas spills. Several researchers have studied the security of UWSNs, but most of the works detect malicious attacks solely based on a certain predefined threshold. It is not optimal to detect malicious attacks after the threshold value is met. In this paper, we propose a multi-factor authentication model that is based on zero-knowledge proof to detect malicious activities and secure UWSNs from several attacks.

Meng Li, Jianbo Gao, Yifei Chen, Jingcheng Zhao · 5 authors

Ride-hailing is a favored vehicular service model where drivers can deliver convenient rides to waiting riders via responding to a road-side unit or a ride-hailing service provider. However, previous works did not consider the order-linking function where a rider Cathy waving for a ride will be matched to a driver Bob in service with rider Alice whose destination is close to the start point of Cathy. Furthermore, a malicious matching executor could collude with an appointed driver to interfere with the matching process, which causes service unfairness and has not been addressed before. To mitigate these limitations, we first propose a privacy-preserving ride-hailing scheme OLink with the verifiable order-linking property. Specifically, we adopt road network partitioning and range query to achieve basic user matching. The user matching process supports range conditions and protects users' privacy. Next, a Proof-of-Linking protocol is designed based on the zero-knowledge succinct non-interactive argument of knowledge, zero-knowledge proof, and Bloom filters to enable the driver in service to generate three consecutive proofs for linking a current order to the next rider's order in advance; the proofs will be released such that anyone can verify the proofs and matching fairness is guaranteed. Finally, we formally prove the privacy and security of OLink, and then evaluate its performance with PySNARK to demonstrate feasibility and efficiency.

Andreas Abraham, Stefan More, Christof Rabensteiner, Felix Hörandner

Identity management systems enable users (i.e., provers) to authenticate and provide attributes to verifiers by using certified credentials obtained from an authority. To accept such a credential, verifiers require information on whether the presented credentials are still valid or if they have been revoked. Up-to-date revocation information can be obtained from a revocation database; however, this requires that the verifier or prover is online. The problem becomes more interesting in the offline case when the prover (e.g., citizen) and verifier (e.g., police officer) do not have an Internet connection to query the revocation status of the presented credential (e.g., digital driver's license). In this paper, we extend the Self-Sovereign Identity (SSI) model to support both revocation as well as offline-verification. Our concept introduces attestations of validity for a point in time, which are issued by the SSI network for credentials that have not been revoked, i.e., added by authorized entities to a revocation list. The concept aims to be generic so that it can be used for various use cases, e.g., by giving users the control over the frequency of re-attestation. To show our concept's feasibility and practicality, we developed and evaluated an implementation that includes an efficient and privacy-preserving showing of credentials using noninteractive zero-knowledge proofs, all while being offline.

Shiwei Xu, Xiaowen Cai, Yizhi Zhao, Zhengwei Ren · 8 authors

Consortium blockchain has been widely used in different scenarios, where blockchain members demand that their uploaded data could be audited under their identities without exposing the data themselves. However, so far, no solution of privacy-preserving data auditing has been proposed. To address the problem, we propose zkrpChain, which focuses on protection of the integrity and privacy of the data uploaded by blockchain members while leaving their identities public. In zkrpChain, which is based on Hyperledger Fabric and Bulletproofs, both standard-range and arbitrary-range zero-knowledge range proofs generation and verification are supported. To improve the efficiency, the aggregation of multiple proofs and batch verification are also developed. For further development, we provide the client codes, chaincodes and related APIs. Finally, we conduct experiments to evaluate the performance of zkrpChaln, and the results show that the consumed time (in an 8-thread scheme) of chaincodes and needed on-chain space of zkrpChain are very close to Bulletproofs, which is evaluated in a single-machine environment.

Sergey Zapechnikov

The paper is devoted to the actual problem of ensuring privacy during performing transactions in distributed ledgers. We discuss various aspects of transaction privacy, as well as the specifics of setting the problem for distributed ledgers with two main models for representing participants' balances: the UTXO-model and the account model. Based on these results, we outline definitions and consider security properties of the main cryptographic primitives used for preserving the privacy of transactions: mixers, ring signatures, homomorphic encryption, and zero-knowledge proofs. We analyze well-known solutions for distributed ledgers based on the UTXO-model, such as Zcash, Monero, Zcoin, Dash, CoinShuffle, Verge, Grin, and others, as well as for systems based on the account model: DSC, Zether, Zeth, BlockMaze. Based on the comparison of advantages, disadvantages, and limitations for existing solutions, conclusions are drawn about the future development of distributed ledgers that ensure the privacy of transactions, and new research tasks are outlined.

Maharage Nisansala Sevwandi Perera, Takeshi Koshiba

An efficient member revocation mechanism is a desirable feature when group signature schemes are applied in practical scenarios. Revocation methods, such as verifier-local revocation (VLR), provide an efficient member revocation in applications of group signatures. However, VLR-group signatures rely on a weaker security notion. On the other hand, group signature schemes for static groups gain stronger security with the full-anonymity security notion. Even though an outsider sees the secret signing keys of all group members in the full-anonymity, the signer is still anonymous. Achieving the full-anonymity for VLR group signature schemes is challenging due to the structure of secret signing keys. The secret signing keys of those schemes consist of tokens, which are used to manage revocation. The reveal of tokens may destroy the anonymity of the signers. We obtain stronger security for the lattice-based VLR group signature schemes by providing a new key generation method, which outputs revocation tokens without deriving from the members’ secret signing keys. We propose a new group signature scheme from lattices with VLR, which achieves stronger security than the previous related works. To avoid signature forgeries, we suggest a new zero-knowledge proof system that requires signers to validate themselves. Moreover, we output an efficient tracing mechanism.

A. V. Siriak, Valentina Turchyna

The problem of constructing a NIZK proof of knowledge of a multivariate polynomial’s zero is considered. A previously developed method for SNARK construction based on Quadratic Arithmetic Programs and Pinocchio protocol is adapted to solve the stated problem efficiently.

Mubarak Umar, Zhenqiang Wu, Xuening Liao

No abstract is available for this record.

Tian Chen, Changhyun Kim, Kevin A. Miceli

Abstract Research Summary Knowledge‐based theories have posited that new technologies are recombinations of prior technologies. To bring about new innovations, inventors usually use past known knowledge as a key ingredient. However, there exists a particular type of new technology that does not have any explicit prior technology predecessors. These pioneering technologies, also referred to as “zero‐reference patents,” not only reflect new knowledge but can also serve as the initial seed from which recombination can subsequently create more knowledge and technologies. We seek to understand the characteristics of the inventors who create these pioneering technologies. We find that having focused, specific expertise is more important than a broad knowledge base in the development of these pioneering technologies, and that prior inventive success can hinder their creation. Managerial Summary We highlight a type of patents which have zero backward references, representing a form of pioneering knowledge. Unlike other types of knowledge, pioneering knowledge comes from inventors who have less successful but more focused experience. Although the zero‐reference patents generally fail to show usefulness on their own, the patents which build upon zero‐reference patents are more likely to become breakthrough patents and to generate a high number of forward citations. Zero‐reference patents are the seeds for future breakthroughs. Given the importance of breakthroughs, we offer an alternative path toward creating such knowledge. Our analysis at the level of inventors also gives guidance on the type of talent who are more likely to generate pioneering knowledge.

Pavlo Gaiduk, Kumar Rajeev Ranjan, Thomas Basmer, Florian Tschorsch

Cooperative intelligent transport systems promise considerable improvements on road safety and the utilization of transport infrastructures. Current approaches, however, build upon policies to protect privacy, which raise serious concerns. In this paper, we propose a privacy-preserving public key infrastructure (PKI) for vehicle-to-everything communication. We use zero-knowledge proofs to authenticate, while still being able to hide identities. In order to exclude malicious actors, we integrate an anonymous reputation-based blacklisting scheme. Our benchmarks on an on-board connectivity unit with resource-constrained hardware confirms the feasibility of the approach. Specifically, we expect approximately 67 kB payload and 35 minutes computation time per day to authenticate.

Ryan Henry, Alyssa Tory, Sophie Henry, Isabella Henry · 5 authors

In this short paper, we revisit the celebrated Naor?Naor?Reingold (NNR) protocol for ?[convincing] people you know where Waldo is without revealing information about his location?. We observe that, despite oft-repeated claims to the contrary, the NNR protocol is neither zero-knowledge nor a proof of knowledge. We propose a slightly more elaborate version that is both of these things?but still eminently suitable for children?s playdates (and the classroom).

Jianbing Ni, Kuan Zhang, Yong Yu, Tingting Yang

As cloud storage services have become popular nowadays, the integrity of outsourced data stored at untrusted servers received increased attention. Provable data possession (PDP) provides an effective and efficient solution for cloud data integrity by asking the cloud server to prove that the stored data are not tampered with or maliciously discarded without returning the actual data to users. In this article, we propose an efficient identity-based privacy-preserving provable data possession scheme (ID-P$^3$DP) based on the RSA assumption for secure cloud storage. In ID-P$^3$DP, a cloud user takes the outsourcing file and a global parameter in a time period as inputs to generate identity-based homomorphic authenticators, and any third-party auditor (TPA) can check the integrity of the outsourced file by verifying the validity of homomorphic authenticators. The distinguished feature of ID-P$^3$DP is to support the aggregation of identity-based homomorphic authenticators generated by different users under the RSA assumption, which is an open problem in provable data possession. Specifically, we transfer the identity-based homomorphic authenticators generated in distinct time periods into those with the same period parameter, and the cloud can compress the homomorphic authenticators of different users to generate a data possession proof for integrity verification. Besides, by exploiting zero-knowledge proof, the leakage of outsourced data to TPA can be prevented. The soundness of ID-P$^3$DP is proved based on the RSA assumption, and the privacy against TPA is perfectly preserved. Finally, we demonstrate ID-P$^3$DP is more efficient on integrity verification than the existing BLS-based schemes, and cross-user aggregate verification can significantly reduce computational and communication overhead for TPA.

Suthee Ruangwises, Toshiya Itoh

An undirected graph $G$ is known to both the prover $P$ and the verifier $V$, but only $P$ knows a subgraph $H$ of $G$. Without revealing any information about $H$, $P$ wants to convince $V$ that $H$ is a connected spanning subgraph of $G$, i.e. $H$ is connected and contains all vertices of $G$. In this paper, we propose an unconventional zero-knowledge proof protocol using a physical deck of cards, which enables $P$ to physically show that $H$ satisfies the condition without revealing it. We also show applications of this protocol to verify solutions of three well-known NP-complete problems: the Hamiltonian cycle problem, the maximum leaf spanning tree problem, and a popular logic puzzle called Bridges.

Oskar Josef Gstrein, Dimitry Kochenov

Distributed Ledger Technology can be an effective tool for resource distribution. As individuals and organisations explore innovations which allow to redefine the rules of access, possession and sharing these developments also become important for the future of self-determination. Demonstrated through credit scoring and ‘social credit systems’, the identity of an individual is intertwined with resource access, possession and transferability. A key pre-requisite for participation is formal legal status, which translates to citizenship. However, many proponents of Distributed Ledger Technology focus predominantly on technological features and capabilities, which might enable the implementation of concepts such as decentralised governance, ‘self-sovereign identity’ management, and trust-less transactions based on ‘zero-knowledge proof’. Nevertheless, such narrow consideration overlooks existing legal and political realities. Considering the lessons learned from citizenship, it becomes questionable whether Blockchain as player in the area of identity management will ultimately increase human dignity, or further manifest traditional patterns of discrimination and inequality.

Joshua Holmes, Gaby G. Dagher

Secure multiparty protocols are useful tools for parties wishing to jointly compute a function while keeping their input data secret. The millionaires' problem is the first secure two-party computation problem, where the goal is to securely compare two private numbers without a trusted third-party. There have been several solutions to the problem; however, these solutions are either insecure in the malicious model or cannot verify the validity of inputs. In this paper, we introduce Variance, a privacy-preserving two-party protocol for solving Yao's millionaires' problem in a Bitcoin setting, in which each party controls several Bitcoin accounts (single and multi signature addresses) and they want to find out who owns more bitcoins without revealing (1) how many accounts they own or the addresses associated with their accounts, (2) the balance of any of their accounts, and (3) their total wealth of bitcoins while assuring the other party that they are not claiming more bitcoin than they possess. We utilize zero knowledge proofs to provide a solution to the problem, and subsequently prove that Variance is secure against active adversaries in the malicious model.

Sofia Terzi, Charalampos Savvaidis, Konstantinos Votis, Dimitrios Tzovaras · 5 authors

Modern Internet of Things (IoT) networks including vehicle networks face an increased demand for security and access control with respect to privacy for sensitive data. Data manipulation and tampering of emissions values due to the economic incentives and environmental and health issues require a tamper-proof solution with the use of blockchain (BC) where the integrity of data is ensured. In this paper, we propose the integration of a public permissioned Self-Sovereign Identities (SSI) framework with a permissioned consortium BC based architecture. This innovatively supports the decentralization of the authentication and authorization processes to overcome the single point of failure problems and the use of SSI to assign identities to IoT devices. Additionally, it gives full control to the holders for their identities, whether they are humans, organizations or smart vehicles. With the practice of advanced zero-knowledge proof (ZKP) cryptographic techniques, the exposure of sensitive and private information is minimized to the absolute necessary and gains in performance and scalability are achieved. Furthermore, the way this ecosystem of technologies is combined guarantees a trusted environment for enabling and automating vehicles' emissions certification according to emissions standards and regulations. Detailed descriptions of the processes required to integrate Hyperledger Indy (HLI) SSIs to authenticate and authorize entities on a Hyperledger Fabric (HLF) network are being quoted.

Suthee Ruangwises, Toshiya Itoh

No abstract is available for this record.