Bringing data minimization to digital wallets at scale with general-purpose zero-knowledge proofs

Today, digital identity management for individuals is either inconvenient and error-prone or creates undesirable lock-in effects and violates privacy and security expectations. These shortcomings inhibit the digital transformation in general and seem particularly concerning in the context of novel applications such as access control for decentralized autonomous organizations and identification in the Metaverse. Decentralized or self-sovereign identity (SSI) aims to offer a solution to this dilemma by empowering individuals to manage their digital identity through machine-verifiable attestations stored in a "digital wallet" application on their edge devices. However, when presented to a relying party, these attestations typically reveal more attributes than required and allow tracking end users' activities. Several academic works and practical solutions exist to reduce or avoid such excessive information disclosure, from simple selective disclosure to data-minimizing anonymous credentials based on zero-knowledge proofs (ZKPs). We first demonstrate that the SSI solutions that are currently built with anonymous credentials still lack essential features such as scalable revocation, certificate chaining, and integration with secure elements. We then argue that general-purpose ZKPs in the form of zk-SNARKs can appropriately address these pressing challenges. We describe our implementation and conduct performance tests on different edge devices to illustrate that the performance of zk-SNARK-based anonymous credentials is already practical. We also discuss further advantages that general-purpose ZKPs can easily provide for digital wallets, for instance, to create "designated verifier presentations" that facilitate new design options for digital identity infrastructures that previously were not accessible because of the threat of man-in-the-middle attacks

Towards Solving the Blockchain Trilemma: An Exploration of Zero-Knowledge Proofs

Research on blockchain has found that the technology is no silver bullet compared to traditional data structures due to limitations regarding decentralization, security, and scalability. These limitations are summarized in the blockchain trilemma, which today represents the greatest barrier to blockchain adoption and applicability. To address these limitations, recent advancements by blockchain businesses have focused on a new cryptographic technique called Zero-knowledge proofs . While these primitives have been around for some time and despite their potential significance on blockchains, not much is known in information systems research about them and their potential effects. Therefore, we employ a multivocal literature review to explore this new tool and find that although it has the potential to resolve the trilemma, it currently only solves it in certain dimensions, which necessitates further attention and research

Towards verifiable differentially-private polling

Analyses that fulfill differential privacy provide plausible deniability to individuals while allowing analysts to extract insights from data. However, beyond an often acceptable accuracy tradeoff, these statistical disclosure techniques generally inhibit the verifiability of the provided information, as one cannot check the correctness of the participants’ truthful information, the differentially private mechanism, or the unbiased random number generation. While related work has already discussed this opportunity, an efficient implementation with a precise bound on errors and corresponding proofs of the differential privacy property is so far missing. In this paper, we follow an approach based on zero-knowledge proofs (ZKPs), in specific succinct non-interactive arguments of knowledge, as a verifiable computation technique to prove the correctness of a differentially private query output. In particular, we ensure the guarantees of differential privacy hold despite the limitations of ZKPs that operate on finite fields and have limited branching capabilities. We demonstrate that our approach has practical performance and discuss how practitioners could employ our primitives to verifiably query individuals’ age from their digitally signed ID card in a differentially private manner

The Value of Graft Implantation Sequence in Simultaneous Pancreas-Kidney Transplantation on the Outcome and Graft Survival

Background/Objectives: The sequence of graft implantation in simultaneous pancreas-kidney transplantation (SPKT) warrants additional study and more targeted focus, since little is known about the short- and long-term effects on the outcome and graft survival after transplantation. Material and methods: 103 patients receiving SPKT in our department between 1999 and 2015 were included in the study. Patients were divided according to the sequence of graft implantation into pancreas-first (PF, n = 61) and kidney-first (KF, n = 42) groups. Clinicopathological characteristics, outcome and survival were reviewed retrospectively. Results: Donor and recipient characteristics were similar. Rates of post-operative complications and graft dysfunction were significantly higher in the PF group compared with the KF group (episodes of acute rejection within the first year after SPKT: 11 (18%) versus 2 (4.8%); graft pancreatitis: 18 (18%) versus 2 (4.8%), p = 0.04; vascular thrombosis of the pancreas: 9 (14.8%) versus 1 (2.4%), p = 0.03; and delayed graft function of the kidney: 12 (19.6%) versus 2 (4.8%), p = 0.019). The three-month pancreas graft survival was significantly higher in the KF group (PF: 77% versus KF: 92.1%; p = 0.037). No significant difference was observed in pancreas graft survival five years after transplantation (PF: 71.6% versus KF: 84.8%; p = 0.104). Kidney graft survival was similar between the two groups. Multivariate analysis revealed order of graft implantation as an independent prognostic factor for graft survival three months after SPKT (HR 2.6, 1.3–17.1, p = 0.026) and five years (HR 3.7, 2.1–23.4, p = 0.040). Conclusion: Our data indicates that implantation of the pancreas prior to the kidney during SPKT has an influence especially on the early-post-operative outcome and survival rate of pancreas grafts

Enabling end-to-end digital carbon emission tracing with shielded NFTs

In the energy transition, there is an urgent need for decreasing overall carbon emissions. Against this background, the purposeful and verifiable tracing of emissions in the energy system is a crucial key element for promoting the deep decarbonization towards a net zero emission economy with a market-based approach. Such an effective tracing system requires end-to-end information flows that link carbon sources and sinks while keeping end consumers’ and businesses’ sensitive data confidential. In this paper, we illustrate how non-fungible tokens with fractional ownership can help to enable such a system, and how zero-knowledge proofs can address the related privacy issues associated with the fine-granular recording of stakeholders’ emission data. Thus, we contribute to designing a carbon emission tracing system that satisfies verifiability, distinguishability, fractional ownership, and privacy requirements. We implement a proof-of-concept for our approach and discuss its advantages compared to alternative centralized or decentralized architectures that have been proposed in the past. Based on a technical, data privacy, and economic analysis, we conclude that our approach is a more suitable technical backbone for end-to-end digital carbon emission tracing than previously suggested solutions

Theodor Mommsen (1817-1903) auf Medaillen und Plaketten. Sammlung des Instituts für Klassische Archäologie der Universität Tübingen.

Zusammenstellung mehrer Beiträge zu den Medaillen und Plaketten auf Theodor Mommsen aus der Sammlung des Instituts für Klassische Archäologie der Universität Tübingen

In-depth analysis of T cell immunity and antibody responses in heterologous prime-boost-boost vaccine regimens against SARS-CoV-2 and Omicron variant.

With the emergence of novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Variants of Concern (VOCs), vaccination studies that elucidate the efficiency and effectiveness of a vaccination campaign are critical to assess the durability and the protective immunity provided by vaccines. SARS-CoV-2 vaccines have been found to induce robust humoral and cell-mediated immunity in individuals vaccinated with homologous vaccination regimens. Recent studies also suggest improved immune response against SARS-CoV-2 when heterologous vaccination strategies are employed. Yet, few data exist on the extent to which heterologous prime-boost-boost vaccinations with two different vaccine platforms have an impact on the T cell-mediated immune responses with a special emphasis on the currently dominantly circulating Omicron strain. In this study, we collected serum and peripheral blood mononuclear cells (PBMCs) from 57 study participants of median 35-year old's working in the health care field, who have received different vaccination regimens. Neutralization assays revealed robust but decreased neutralization of Omicron VOC, including BA.1 and BA.4/5, compared to WT SARS-CoV-2 in all vaccine groups and increased WT SARS-CoV-2 binding and neutralizing antibodies titers in homologous mRNA prime-boost-boost study participants. By investigating cytokine production, we found that homologous and heterologous prime-boost-boost-vaccination induces a robust cytokine response of CD4+ and CD8+ T cells. Collectively, our results indicate robust humoral and T cell mediated immunity against Omicron in homologous and heterologous prime-boost-boost vaccinated study participants, which might serve as a guide for policy decisions

Towards Verifiable Differentially-Private Polling

Analyses that fulfill differential privacy provide plausible deniability to individuals while allowing analysts to extract insights from data. However, beyond an often acceptable accuracy tradeoff, these statistical disclosure techniques generally inhibit the verifiability of the provided information, as one cannot check the correctness of the participants' truthful information, the differentially private mechanism, or the unbiased random number generation. While related work has already discussed this opportunity, an efficient implementation with a precise bound on errors and corresponding proofs of the differential privacy property is so far missing. In this paper, we follow an approach based on zero-knowledge proofs~(ZKPs), in specific succinct non-interactive arguments of knowledge, as a verifiable computation technique to prove the correctness of a differentially private query output. In particular, we ensure the guarantees of differential privacy hold despite the limitations of ZKPs that operate on finite fields and have limited branching capabilities. We demonstrate that our approach has practical performance and discuss how practitioners could employ our primitives to verifiably query individuals' age from their digitally signed ID card in a differentially private manner

The Effects of Oral Anticoagulant Exposure on the Surgical Outcomes of Patients Undergoing Surgery for High-Risk Abdominal Emergencies

Background!#!In chronic anticoagulant users undergoing surgery, bleeding and thromboembolism are common and serious complications. Many studies on mainly elective or minor emergency surgical procedures with low associated risks have focused on these outcomes. In comparison, patients undergoing high-risk emergency abdominal surgical procedures have not received sufficient attention. This study aimed to compare outcomes between oral anticoagulant users and nonusers who required emergency laparotomy for high-risk abdominal emergencies.!##!Methods!#!Patients who underwent surgery for abdominal emergencies at our institution between January 2012 and July 2019 were retrospectively reviewed.!##!Results!#!There were 875 patients, including 370 anticoagulant users and 505 nonusers. Of the 370 anticoagulant users, 189 (51.3), 77 (20.8%), 45 (12.2%), and 59 (15.9%) were prescribed antiplatelets, a vitamin k antagonist, a direct oral anticoagulant, and a combination drug regimen, respectively. The most common high-risk emergencies requiring surgery in both groups were perforated viscus (25.7% vs 40.9%), mesenteric ischemia with enteric necrosis (27% vs 12.8%), and bowel obstruction (17.6% vs 28.1%). The overall bleeding rate was higher (29.2% vs 22%, p = 0.015) in anticoagulant users than in nonusers, but the major bleeding rate was similar (17.8% vs 14.1%, p = 0.129) between the two groups. The rates of thromboembolic events and mortality were significantly higher in anticoagulant users than in nonusers (25.7% vs 9.7%, p < 0.0001 and 39.7% vs 31.1%, p = 0.01, respectively). Liver cirrhosis, peripheral arterial diseases, reoperation, and blood product transfusion were independent predictors of the overall risk of bleeding or TEEs, according to the multivariate analysis. In this model, liver cirrhosis had the largest overall effect on mortality, followed by pneumonia, thromboembolism, peripheral arterial disease, blood product transfusion, and atrial fibrillation. The use of oral anticoagulants was not an independent predictor of either bleeding or in-hospital mortality. The use of oral anticoagulants was associated with a decreased risk of all-cause in-hospital mortality.!##!Conclusion!#!Based on our results, the continued use of oral anticoagulants is more protective than harmful considering the overall outcomes in this subset of patients