A formal definition and a new security mechanism of physical unclonable functions

The characteristic novelty of what is generally meant by a "physical unclonable function" (PUF) is precisely defined, in order to supply a firm basis for security evaluations and the proposal of new security mechanisms. A PUF is defined as a hardware device which implements a physical function with an output value that changes with its argument. A PUF can be clonable, but a secure PUF must be unclonable. This proposed meaning of a PUF is cleanly delineated from the closely related concepts of "conventional unclonable function", "physically obfuscated key", "random-number generator", "controlled PUF" and "strong PUF". The structure of a systematic security evaluation of a PUF enabled by the proposed formal definition is outlined. Practically all current and novel physical (but not conventional) unclonable physical functions are PUFs by our definition. Thereby the proposed definition captures the existing intuition about what is a PUF and remains flexible enough to encompass further research. In a second part we quantitatively characterize two classes of PUF security mechanisms, the standard one, based on a minimum secret read-out time, and a novel one, based on challenge-dependent erasure of stored information. The new mechanism is shown to allow in principle the construction of a "quantum-PUF", that is absolutely secure while not requiring the storage of an exponentially large secret. The construction of a PUF that is mathematically and physically unclonable in principle does not contradict the laws of physics.Comment: 13 pages, 1 figure, Conference Proceedings MMB & DFT 2012, Kaiserslautern, German

Greater Expectations?

Physically Unclonable Functions (PUFs) are key tools in the construction of lightweight authentication and key exchange protocols. So far, all existing PUF-based authentication protocols follow the same paradigm: A resource-constrained prover, holding a PUF, wants to authenticate to a resource-rich verifier, who has access to a database of pre-measured PUF challenge-response pairs (CRPs). In this paper we consider application scenarios where all previous PUF-based authentication schemes fail to work: The verifier is resource-constrained (and holds a PUF), while the prover is resource-rich (and holds a CRP-database). We construct the first and efficient PUF-based authentication protocol for this setting, which we call converse PUF-based authentication. We provide an extensive security analysis against passive adversaries, show that a minor modification also allows for authenticated key exchange and propose a concrete instantiation using controlled Arbiter PUFs

Moving from a Product-Based Economy to a Service-Based Economy for a More Sustainable Future

Traditionally, economic growth and prosperity have been linked with the availability, production and distribution of tangible goods as well as the ability of consumers to acquire such goods. Early evidence regarding this connection dates back to Adam Smith's Wealth of Nations (1776), in which any activity not resulting in the production of a tangible good is characterized as unproductive of any value." Since then, this coupling of economic value and material production has been prevalent in both developed and developing economies throughout the world. One unintended consequence of this coupling has been the exponential increase in the amount of solid waste being generated. The reason is that any production and consumption of material goods eventually generates the equivalent amount of (or even more) waste. Exacerbating this problem is the fact that, with today's manufacturing and supply chain management technologies, it has become cheaper to dispose and replace most products rather than to repair and reuse them. This has given rise to what some call a disposable society." To put things in perspective: In 2012 households in the U.K. generated approximately 22 thousand tons of waste, which amounted to 411 kg of waste generated per person (Department for Environment, Food & Rural Affairs, 2015). During the same time period, households in the U.S. generated 251 million tons of waste, which is equivalent to a person generating approximately 2 kg of waste every day (U.S. Environmental Protection Agency, 2012). Out of these 251 million tons of total waste generated, approximately 20% of the discarded items were categorized as durable goods. The disposal of durable goods is particularly worrisome because they are typically produced using material from non- renewable resources such as iron, minerals, and petroleum-based raw materials

Yard-Sale exchange on networks: Wealth sharing and wealth appropriation

Yard-Sale (YS) is a stochastic multiplicative wealth-exchange model with two phases: a stable one where wealth is shared, and an unstable one where wealth condenses onto one agent. YS is here studied numerically on 1d rings, 2d square lattices, and random graphs with variable average coordination, comparing its properties with those in mean field (MF). Equilibrium properties in the stable phase are almost unaffected by the introduction of a network. Measurement of decorrelation times in the stable phase allow us to determine the critical interface with very good precision, and it turns out to be the same, for all networks analyzed, as the one that can be analytically derived in MF. In the unstable phase, on the other hand, dynamical as well as asymptotic properties are strongly network-dependent. Wealth no longer condenses on a single agent, as in MF, but onto an extensive set of agents, the properties of which depend on the network. Connections with previous studies of coalescence of immobile reactants are discussed, and their analytic predictions are successfully compared with our numerical results.Comment: 10 pages, 7 figures. Submitted to JSTA

The impact of histopathology and NAB2-STAT6 fusion subtype in classification and grading of meningeal solitary fibrous tumor/hemangiopericytoma.

Meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is a rare tumor with propensity for recurrence and metastasis. Although multiple classification schemes have been proposed, optimal risk stratification remains unclear, and the prognostic impact of fusion status is uncertain. We compared the 2016 WHO CNS tumor grading scheme (CNS-G), a three-tier system based on histopathologic phenotype and mitotic count, to the 2013 WHO soft-tissue counterpart (ST-G), a two-tier system based on mitotic count alone, in a cohort of 133 patients [59 female, 74 male; mean age 54 years (range 20-87)] with meningeal SFT/HPC. Tumors were pathologically confirmed through review of the first tumor resection (n = 97), local recurrence (n = 35), or distant metastasis (n = 1). A STAT6 immunostain showed nuclear expression in 132 cases. NAB2-STAT6 fusion was detected in 99 of 111 successfully tested tumors (89%) including the single STAT6 immunonegative tumor. Tumors were classified by CNS-G as grade 1 (n = 43), 2 (n = 41), or 3 (n = 49), and by ST-G as SFT (n = 84) or malignant SFT (n = 49). Necrosis was present in 16 cases (12%). On follow-up, 42 patients had at least one subsequent recurrence or metastasis (7 metastasis only, 33 recurrence only, 2 patients had both). Twenty-nine patients died. On univariate analysis, necrosis (p = 0.002), CNS-G (p = 0.01), and ST-G (p = 0.004) were associated with recurrence-free (RFS) but not overall survival (OS). NAB2-STAT6 fusion type was not significantly associated with RFS or OS, but was associated with phenotype. A modified ST-G incorporating necrosis showed higher correlation with RFS (p = 0.0006) and remained significant (p = 0.02) when considering only the primary tumors. From our data, mitotic rate and necrosis appear to stratify this family of tumors most accurately and could be incorporated in a future grading scheme

Citrus junos as a host of citrus bacterial canker

Following a request from the European Commission, the European Food Safety Authority (EFSA) Plant Health (PLH) Panel analysed a dossier submitted by the Japanese authorities in order to clarify the host status of Citrus junos with regard to Xanthomonas citri pv. citri and Xanthomonas citri pv. aurantifolii, causal agents of citrus bacterial canker, and to indicate whether C. junos fruit could represent a pathway for the introduction of citrus bacterial canker into the European Union. In a previous opinion in the year 2014, the EFSA PLH Panel concluded that commercial fresh citrus fruit is generally pathway and that no commercially important Citrus species or variety can be considered as immune to citrus bacterial canker. In the current assessment, the EFSA PLH Panel analysed the two scientific papers provided by the Japanese authorities, as well as 16 additional papers identified through a systematic literature review. The PLH Panel considered that the conclusions of its previous opinion remain valid and that convergent lines of evidence provide sufficient demonstration that C. junos is a host of X. citri pv. citri and X. citri pv. aurantifolii. Therefore, there is no reason to consider the C. junos fruit differently from other citrus species. Consequently, the assessment of the general citrus fruit pathway from the 2014 opinion still applies. Uncertainties on these conclusions are a result of the scarce scientific evidence published on this subject in addition to the methodological and reporting limitations of the published papers

Modelos explicativos da memória prospectiva: uma revisão teórica

Neste artigo é apresentada uma revisão da literatura sobre os mecanismos cognitivos associados à memória prospectiva, organizados de acordo com a divisão das diferentes fases da recordação prospectiva (i.e., codificação, retenção e recuperação). Inicialmente, é apresentada a diversidade de dados da investigação que sustentam diferentes abordagens explicativas do fenômeno de recuperação de intenções, considerando a natureza automática ou estratégica da memória prospectiva. Em seguida, são salientadas as potenciais explicações sobre os mecanismos presentes durante o intervalo de retenção e na fase de codificação.(undefined

Contracting outsourced services with collaborative key performance indicators

While service outsourcing may benefit from the application of performance‐based contracts (PBCs), the implementation of such contracts is usually challenging. Service performance is often not only dependent on supplier effort but also on the behavior of the buying firm. Existing research on performance‐based contracting provides very limited understanding on how this challenge may be overcome. This article describes a design science research project that develops a novel approach to buyer–supplier contracting, using collaborative key performance indicators (KPIs). Collaborative KPIs evaluate and reward not only the supplier contribution to customer performance but also the customer's behavior to enable this. In this way, performance‐based contracting can also be applied to settings where supplier and customer activities are interdependent, while traditional contracting theories suggest that output controls are not effective under such conditions. In the collaborative KPI contracting process, indicators measure both supplier and customer (buying firm) performance and promote collaboration by being defined through a collaborative process and by focusing on end‐of‐process indicators. The article discusses the original case setting of a telecommunication service provider experiencing critical problems in outsourcing IT services. The initial intervention implementing this contracting approach produced substantial improvements, both in performance and in the relationship between buyer and supplier. Subsequently, the approach was tested and evaluated in two other settings, resulting in a set of actionable propositions on the efficacy of collaborative KPI contracting. Our study demonstrates how defining, monitoring, and incentivizing the performance of specific processes at the buying firm can help alleviate the limitations of traditional performance‐based contracting when the supplier's liability for service performance is difficult to verify

Balancing the immune response in the brain: IL-10 and its regulation

Background: The inflammatory response is critical to fight insults, such as pathogen invasion or tissue damage, but if not resolved often becomes detrimental to the host. A growing body of evidence places non-resolved inflammation at the core of various pathologies, from cancer to neurodegenerative diseases. It is therefore not surprising that the immune system has evolved several regulatory mechanisms to achieve maximum protection in the absence of pathology. Main body: The production of the anti-inflammatory cytokine interleukin (IL)-10 is one of the most important mechanisms evolved by many immune cells to counteract damage driven by excessive inflammation. Innate immune cells of the central nervous system, notably microglia, are no exception and produce IL-10 downstream of pattern recognition receptors activation. However, whereas the molecular mechanisms regulating IL-10 expression by innate and acquired immune cells of the periphery have been extensively addressed, our knowledge on the modulation of IL-10 expression by central nervous cells is much scattered. This review addresses the current understanding on the molecular mechanisms regulating IL-10 expression by innate immune cells of the brain and the implications of IL-10 modulation in neurodegenerative disorders. Conclusion: The regulation of IL-10 production by central nervous cells remains a challenging field. Answering the many remaining outstanding questions will contribute to the design of targeted approaches aiming at controlling deleterious inflammation in the brain.We acknowledge the Portuguese Foundation for Science and Technology (FCT) for providing a PhD grant to DLS (SFRH/BD/88081/2012) and a post-doctoral fellowship to SR (SFRH/BPD/72710/2010). DS, AGC and SR were funded by FEDER through the Competitiveness Factors Operational Programme (COMPETE) and National Funds through FCT under the scope of the project POCI-01-0145-FEDER007038; and by the project NORTE-01-0145-FEDER-000013, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). The MS lab was financed by Fundo Europeu de Desenvolvimento Regional (FEDER) funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT in the framework of the project “Institute for Research and Innovation in Health Sciences ” (POCI-01-0145-FEDER-007274). MS is a FCT Associate Investigator. The funding body had no role in the design of the study and collection, analysis, and interpretation of the data and in writing the manuscript

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)