380 research outputs found
Association between oxytocin receptor gene polymorphisms and self-rated 'empathic concern' in schizophrenia
The nonapeptide oxytocin (OXT) and its receptor (OXTR) have been implicated in social cognition, empathy, emotion and stress regulation in humans. Previous studies reported associations between OXT and OXTR genetic polymorphisms and risk for disorders characterized by impaired socio-emotional functioning, such as schizophrenia and autism. Here we investigate the influence of two single nucleotide polymorphisms (SNPs) within the OXTR gene on a measure of socio-emotional functioning in schizophrenic patients. OXTR SNPs that were previously investigated in other studies were genotyped in 145 patients diagnosed with schizophrenia according to DSM-IV and 145 healthy controls matched for age and gender. The Interpersonal Reactivity Index (IRI) was used to assess cognitive ('perspective taking'), affective ('empathic concern') and self-related ('personal distress') dimensions of empathy. No group differences in genotype frequencies were observed. MANCOVA revealed a significant main (F [1,282] = 10.464; pGG) with 'empathic concern'. Within the schizophrenia group, linear regression analysis determined OXTR rs2254298 genotype, PANSS negative and general symptom score, and age of disease onset as being significantly associated with 'empathic concern'. OXTR rs2254298 significantly impacted PANSS general psychopathology scores. No associations were found for OXTR rs53576, IRI 'perspective taking' or 'personal distress' ratings. Our preliminary findings support hypotheses about an involvement of OXTR rs2254298 in emotional empathy in schizophrenic and healthy individuals, warranting independent replication
Freiwilligenarbeit: Gegenwärtige Trends und Herausforderungen eines weiten (Forschungs-)Feldes: Sandra A. Habeck, Freiwilligenmanagement. Exploration eines erwachsenenpädagogischen Berufsfeldes. Wiesbaden: Springer VS 2015, 302 S., br., 39,99 €Elisabeth Heite, Bürgerschaftliches Engagement älterer Menschen im Stadtteil. Gleiche Beteiligungschancen und Mitgestaltungsmöglichkeiten für alle? Freiburg: Centaurus 2012, 131 S., br., 18,80 €Gisela Notz, "Freiwilligendienste" für alle. Von der ehrenamtlichen Tätigkeit zur Prekarisierung der "freiwilligen" Arbeit. Neu-Ulm: AG SPAK 2012, 120 S., br., 10,00 €Carola Reifenhäuser / Oliver Reifenhäuser (Hrsg.), Praxishandbuch Freiwilligenmanagement. Weinheim: Beltz Juventa 2013, 215 S., br., 19,95 €Lisa Katrin Schürmann, Motivation und Anerkennung im freiwilligen Engagement. Kampagnen und ihre Umsetzung in Internet und Social Media. Wiesbaden: Springer VS 2013, 120 S., br., 29,99 €Schweizerisches Rotes Kreuz (Hrsg.), Freiwilligkeit und Vielfalt im Zeichen der Menschlichkeit. Zürich: Seismo 2014, 380 S., kt., 29,00 €David Wenzel / Irmtraud Beerlage / Silke Springer, Motivation und Haltekraft im Ehrenamt. Die Bedeutung von Organisationsmerkmalen für Engagement, Wohlbefinden und Verbleib in Freiwilliger Feuerwehr und THW. Freiburg: Centaurus 2012, 190 S., br., 23,80 €
Design process robustness: A bi-partite network analysis reveals the central importance of people
Design processes require the joint effort of many people to collaborate and work on multiple activities. Effective techniques to analyse and model design processes are important for understanding organisational dynamics, for improving collaboration, and for planning robust design processes, reducing the risk of rework and delays. Although there has been much progress in modelling and understanding design processes, little is known about the interplay between people and the activities they perform and its influence on design process robustness. To analyse this interplay, we model a large-scale design process of a biomass power plant with people and activities as a bipartite network. Observing that some people act as bridges between activities organised to form nearly independent modules, in order to evaluate process fragility, we simulate random failures and targeted attacks to people and activities. We find that our process is more vulnerable to attacks to people rather than activities. These findings show how the allocation of people to activities can obscure an inherent fragility, making the process highly sensitive and dependent on specific people. More generally, we show that the behaviour of robustness is determined by the degree distributions, the heterogeneity of which can be leveraged to improve robustness and resilience to cascading failures. Overall, we show that it is important to carefully plan the assignment of people to activities
Sprachkompetenz als Prädiktor mathematischer Kompetenzentwicklung von Kindern deutscher und nicht-deutscher Familiensprache
Das Ziel des vorliegenden Beitrages bestand darin, anhand der längsschnittlich angelegten Studie Erhebungen zum Lese- und Mathematikverständnis-Entwicklungen in den Jahrgangsstufen 4 bis 6 in Berlin (ELEMENT) den Einfluss von Lesekompetenz auf die Kompetenzentwicklung in Mathematik bei Schülerinnen und Schülern von der 4. bis zur 6. Jahrgangsstufe (N = 3 169) zu analysieren. Darüber hinaus wurde untersucht, ob Kinder nicht-deutscher Familiensprache unter Kontrolle des sozioökonomischen Status (SES) und der allgemeinen kognitiven Grundfähigkeiten geringere Lernzuwächse in Mathematik erzielen als Kinder deutscher Familiensprache. Der Entwicklungsverlauf der Mathematikkompetenz wurde dabei anhand eines Wachstumskurvenmodells analysiert. Erwartungskonform zeigte sich, dass die Lesekompetenz, auch unter Kontrolle des SES und der allgemeinen kognitiven Grundfähigkeiten, nicht nur signifikant mit der mathematischen Ausgangskompetenz zusammenhing, sondern darüber hinaus auch einen signifikanten Beitrag zur Vorhersage der mathematischen Lernzuwachsraten aller Schülerinnen und Schüler leistete. Obwohl die bestehenden Kompetenzunterschiede in Mathematik zwischen Kindern nicht-deutscher Familiensprache und deutscher Familiensprache größtenteils auf die Lesekompetenz zurückführbar waren, vergrößerten sich die Disparitäten zwischen Kindern deutscher und Kindern nicht-deutscher Familiensprache nicht. (DIPF/Orig.)The aim of the present study was to investigate whether reading comprehension predicts learning gains in mathematics from the fourth to the sixth grade. The study also examined whether second-language learners show smaller learning gains in mathematics than students whose first language is German when socioeconomic status and basic cognitive abilities are controlled for. Learning gains in mathematics (N = 3,169) were modeled using a latent growth model. The findings indicate that the reading comprehension of children predicts not only their mathematical competence in Grade 4, but also their learning gains in mathematics from Grades 4 to 6. Further analyses revealed that differences in mathematical competence between second-language learners and students whose first language is German disappear when controlling for reading comprehension. However, no differences were found in mathematical learning gains between second-language learners and students whose first language is German. (DIPF/Orig.
Password-Based Credentials with Security against Server Compromise
Password-based credentials (PBCs), introduced by Zhang et al. (NDSS\u2720), provide an elegant solution to secure, yet convenient user authentication. Therein the user establishes a strong cryptographic access credential with the server. To avoid the assumption of secure storage on the user side, the user does not store the credential directly, but only a password-protected version of it. The ingenuity of PBCs is that the password-based credential cannot be offline attacked, offering essentially the same strong security as standard key-based authentication. This security relies on a secret key of the server that is needed to verify whether an authentication token derived from a password-based credential and password is correct. However, the work by Zhang et al. assumes that this server key never gets compromised, and their protocol loses all security in case of a breach. As such a passive leak of the server\u27s stored verification data is one of the main threats in user authentication, our work aims to strengthen PBC to remain secure even when the server\u27s key got compromised.
We first show that the desired security against server compromise is impossible to achieve in the original framework. We then introduce a modified version of PBCs that circumvents our impossibility result and formally define a set of security properties, each being optimal for the respective corruption setting. Finally, we propose a surprisingly simple construction that provably achieves our stronger security guarantees, and is generically composed from basic building blocks
Multi-Signatures for Ad-hoc and Privacy-Preserving Group Signing
Multi-signatures allow to combine individual signatures from different signers on the same message into a short aggregated signature. Newer schemes further allow to aggregate the individual public keys, such that the combined signature gets verified against a short aggregated key. This makes them a versatile alternative to threshold or distributed signatures: the aggregated key can serve as group key, and signatures under that key can only be computed with the help of all signers. What makes multi-signatures even more attractive is their simple key management, as users can re-use the same secret key in several and ad-hoc formed groups. In that context, it will be desirable to not sacrifice privacy as soon as keys get re-used and ensure that users are not linkable across groups. In fact, when multi-signatures with key aggregation were proposed, it was claimed that aggregated keys hide the signers\u27 identities or even the fact that it is a combined key at all. In our work, we show that none of the existing multi-signature schemes provide these privacy guarantees when keys get re-used in multiple groups. This is due to the fact that all known schemes deploy deterministic key aggregation. To overcome this limitation, we propose a new variant of multi-signatures with probabilistic yet verifiable key aggregation. We formally define the desirable privacy and unforgeability properties in the presence of key re-use. This also requires to adapt the unforgeability model to the group setting, and ensure that key-reuse does not weaken the expected guarantees. We present a simple BLS-based scheme that securely realizes our strong privacy and security guarantees. We also formalize and investigate the privacy that is possible by deterministic schemes, and prove that existing schemes provide the advertised privacy features as long as one public key remains secret
Privacy-Preserving Outsourced Certificate Validation
Digital Covid certificates are the first widely deployed end-user cryptographic certificates. For service providers, such as airlines or event ticket vendors, that needed to check that their (global) customers satisfy certain health policies, the verification of such Covid certificates was challenging though - not because of the cryptography involved, but due to the multitude of issuers, different certificate types and the evolving nature of country-specific policies that had to be supported. As Covid certificates contain sensitive health information, their (online) presentation to non-health related entities also poses clear privacy risk. To address both challenges, the EU proposed a specification for outsourcing the verification process to a validator service, that executes the process and informs service providers of the result. The WHO announced to adopt this approach for general vaccination credentials beyond Covid-19. While being beneficial to improve security and privacy for service providers, their solution requires strong trust assumption for the (central) validation service that learns all health-related details of the users.
In our work, we propose and formally model a privacy-preserving variant of such an outsourced validation service. Therein the validator learns the attributes it is supposed to verify, but not the users identity. Still, the validator\u27s assertion is blindly bound to the user\u27s identity to ensure the desired user-binding. We analyze the EU specification in our model and show that it only meets a subset of those goals. Our analysis further shows that the EU protocol is unnecessarily complex and can be significantly simplified while maintaining the same (weak) level of security. Finally, we propose a new construction for privacy-preserving certificate validation that provably satisfies all desired goals
Group Signatures with User-Controlled and Sequential Linkability
Group signatures allow users to create signatures on behalf of a group while remaining anonymous. Such signatures are a powerful tool to realize privacy-preserving data collections, where e.g., sensors, wearables or vehicles can upload authenticated measurements into a data lake. The anonymity protects the user’s privacy yet enables basic data processing of the uploaded unlinkable information. For many applications, full anonymity is often neither desired nor useful though, and selected parts of the data must eventually be correlated after being uploaded. Current solutions of group signatures do not provide such functionality in a satisfactory way: they either rely on a trusted party to perform opening or linking of signatures, which clearly conflicts with the core privacy goal of group signatures; or require the user to decide upon the linkability of signatures before they are generated.
In this paper we propose a new variant of group signatures that provides linkability in a flexible and user-centric manner. Users – and only they – can decide before and after signature creation whether they should remain linkable or be correlated. To prevent attacks where a user omits certain signatures when a sequence of events in a certain section (e.g., time frame), should be linked, we further extend this new primitive to allow for sequential link proofs. Such proofs guarantee that the provided sequence of data is not only originating from the same signer, but also occurred in that exact order and contains all of the user’s signatures within the time frame. We formally define the desired security and privacy properties, propose a provably secure construction based on DL-related assumptions and report on a prototypical implementation of our scheme
Provable Security Analysis of the Secure Remote Password Protocol
This paper analyses the Secure Remote Password Protocol (SRP) in the context of provable security. SRP is an asymmetric Password-Authenticated Key Exchange (aPAKE) protocol introduced in 1998. It allows a client to establish a shared cryptographic key with a server based on a password of potentially low entropy. Although the protocol was part of several standardization efforts, and is deployed in numerous commercial applications such as Apple Homekit, 1Password or Telegram, it still lacks a formal proof of security. This is mainly due to some of the protocol\u27s design choices which were implemented to circumvent patent issues.
Our paper gives the first security analysis of SRP in the universal composability (UC) framework. We show that SRP is UC-secure against passive eavesdropping attacks under the standard CDH assumption in the random oracle model. We then highlight a major protocol change designed to thwart active attacks and propose a new assumption -- the additive Simultaneous Diffie Hellman (aSDH) assumption -- under which we can guarantee security in the presence of an active attacker. Using this new assumption as well as the Gap CDH assumption, we prove security of the SRP protocol against active attacks. Our proof is in the Angel-based UC framework , a relaxation of the UC framework which gives all parties access to an oracle with super-polynomial power. In our proof, we assume that all parties have access to a DDH oracle (limited to finite fields). We further discuss the plausibility of this assumption and which level of security can be shown without it
Privacy for Distributed Databases via (Un)linkable Pseudonyms
When data maintained in a decentralized fashion needs to be synchronized or exchanged between different databases, related data sets usually get associated with a unique identifier. While this approach facilitates cross-domain data exchange, it also comes with inherent drawbacks in terms of controllability. As data records can easily be linked, no central authority can limit or control the information flow. Worse, when records contain sensitive personal data, as is for instance the case in national social security systems, such linkability poses a massive security and privacy threat. An alternative approach is to use domain-specific pseudonyms, where only a central authority knows the cross-domain relation between the pseudonyms. However, current solutions require the central authority to be a fully trusted party, as otherwise it can provide false conversions and exploit the data it learns from the requests. We propose an (un)linkable pseudonym system that overcomes those limitations, and enables controlled yet privacy-friendly exchange of distributed data. We prove our protocol secure in the UC framework and provide an efficient instantiation based on discrete-logarithm related assumptions
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