APTE: An Algorithm for Proving Trace Equivalence

This paper presents APTE, a new tool for automatically proving the security of cryptographic protocols. It focuses on proving trace equivalence between processes, which is crucial for specifying privacy type properties such as anonymity and unlinkability. The tool can handle protocols expressed in a calculus similar to the applied-pi calculus, which allows us to capture most existing protocols that rely on classical cryptographic primitives. In particular, APTE handles private channels and else branches in protocols with bounded number of sessions. Unlike most equivalence verifier tools, APTE is guaranteed to terminate Moreover, APTE is the only tool that extends the usual notion of trace equivalence by considering ``side-channel'' information leaked to the attacker such as the length of messages and the execution times. We illustrate APTE on different case studies which allowed us to automatically (re)-discover attacks on protocols such as the Private Authentication protocol or the protocols of the electronic passports

Physical inactivity amplifies the negative association between sleep quality and depressive symptoms.

Poor sleep quality and physical inactivity are known risk factors for depressive symptoms. Yet, whether these factors differently contribute to depressive symptoms and whether they interact with one another remains unclear. Here, we examined how sleep quality and physical activity influence depressive symptoms in 79,274 adults 50 years of age or older (52.4% women) from the Survey of Health, Aging and Retirement in Europe (SHARE) study. Sleep quality (poor vs. good), physical activity (inactive vs. active), and depressive symptoms (0 to 12 score) were repeatedly collected (7 waves of data collection) between 2004 and 2017. Results showed that sleep quality and physical activity were associated with depressive symptoms. Specifically, participants with poorer sleep quality reported more depressive symptoms than participants with better sleep quality (b = 1.85, 95% CI = 1.83-1.86, p < .001). Likewise, compared to physically active participants, physically inactive participants reported more depressive symptoms (b = 0.44, 95% CI = 0.42-0.45, p < .001). Moreover, sleep quality and physical activity showed an interactive association with depressive symptoms (b = 0.17, 95% CI = 0.13-0.20, p < .001). The negative association between poor sleep quality and higher depressive symptoms was stronger in physically inactive than active participants. These findings suggest that, in adults 50 years of age or older, both poor sleep quality and physical inactivity are related to an increase in depressive symptoms. Moreover, the detrimental association between poor sleep quality and depressive symptoms is amplified in physically inactive individuals

The hitchhiker's guide to decidability and complexity of equivalence properties in security protocols

International audiencePrivacy-preserving security properties in cryptographic protocols are typically modelled by observational equivalences in process calculi such as the applied pi-calulus. We survey decidability and complexity results for the automated verification of such equivalences, casting existing results in a common framework which allows for a precise comparison. This unified view, beyond providing a clearer insight on the current state of the art, allowed us to identify some variations in the statements of the decision problems-sometimes resulting in different complexity results. Additionally, we prove a couple of novel or strengthened results

Enforcing Privacy in the Presence of Others: Notions, Formalisations and Relations

Protecting privacy against bribery/coercion is a necessary requirement in electronic services, like e-voting, e-auction and e-health. Domain-specific privacy properties have been proposed to capture this. We generalise these properties as enforced privacy: a system enforces a user's privacy even when the user collaborates with the adversary. In addition, we account for the influence of third parties on a user's privacy. Third parties can help to break privacy by collaborating with the adversary, or can help to protect privacy by cooperating with the target user. We propose independency of privacy to capture the negative privacy impact that third parties can have, and coalition privacy to capture their positive privacy impact. We formally define these privacy notions in the applied pi calculus and build a hierarchy showing their relations

When Are Three Voters Enough for Privacy Properties?

International audienceProtocols for secure electronic voting are of increasing societal importance. Proving rigorously their security is more challenging than many other protocols, which aim at authentication or key exchange. One of the reasons is that they need to be secure for an arbitrary number of malicious voters. In this paper we identify a class of voting protocols for which only a small number of agents needs to be considered: if there is an attack on vote privacy then there is also an attack that involves at most 3 voters (2 honest voters and 1 dishonest voter). In the case where the protocol allows a voter to cast several votes and counts, e.g., only the last one, we also reduce the number of ballots required for an attack to 10, and under some additional hypotheses, 7 ballots. Our results are formalised and proven in a symbolic model based on the applied pi calculus. We illustrate the applicability of our results on several case studies, including different versions of Helios and Prêt-` a-Voter, as well as the JCJ protocol. For some of these protocols we can use the ProVerif tool to provide the first formal proofs of privacy for an unbounded number of voters

Communication, development, and social change in Spain: A field between institutionalization and implosion

This paper renders an account of the rapid institutionalization of the academic field of Communication for Development and Social Change (CDCS) in Spain in recent years following a period of neglect and marginalization. The ongoing expansion of the field of CDSC in the Spanish context is understood as a process of implosion, i.e. a collapse inwards, which results from the inconsistencies and weaknesses of fast and late institutionalization. The methodological approach for this inquiry is a documental review of both academic literature and research and institutional reports produced in Spain between 1980 and 2010. Based on this review, the paper contrasts the trajectory of the field in Spain with the debates at the international level, establishing relevant continuities and differences.This article is part of the Research Project (Ministry of Economy and Competitiveness, Spain) CSO2014-52005-R titled ‘Evaluation and Monitoring of Communication for Development and Social Change in Spain: design of indicators to measure its social impact’ (2015–2017)17 página

Staying active under restrictions: Changes in type of physical exercise during the initial COVID-19 lockdown

Copyright: © 2021 by the authors. The COVID-19 pandemic and the associated governmental restrictions suddenly changed everyday life and potentially affected exercise behavior. The aim of this study was to explore whether individuals changed their preference for certain types of physical exercise during the pandemic and to identify risk factors for inactivity. An international online survey with 13,881 adult participants from 18 countries/regions was conducted during the initial COVID-19 related lock-down (between April and May 2020). Data on types of exercise performed during and before the initial COVID-19 lockdown were collected, translated, and categorized (free-text input). Sankey charts were used to investigate these changes, and a mixed-effects logistic regression model was used to analyze risks for inactivity. Many participants managed to continue exercising but switched from playing games (e.g., football, tennis) to running, for example. In our sample, the most popular exercise types during the initial COVID-19 lockdown included endurance, muscular strength, and multimodal exercise. Regarding risk factors, higher education, living in rural areas, and physical activity before the COVID-19 lockdown reduced the risk for inactivity during the lockdown. In this relatively active multinational sample of adults, most participants were able to continue their preferred type of exercise despite restrictions, or changed to endurance type activities. Very few became physically inactive. It seems people can adapt quickly and that the constraints imposed by social distancing may even turn into an opportunity to start exercising for some. These findings may be helpful to identify individuals at risk and optimize interventions following a major context change that can disrupt the exercise routine

Reflected near-field blast pressure measurements using high speed video

Background: The design and analysis of protective systems requires a detailed understanding of, and the ability to accurately predict, the distribution of pressure loads acting on an obstacle following an explosive detonation. In particular, there is a pressing need for accurate characterisation of blast loads in the region very close to a detonation, where even small improvised devices can produce serious structural or material damage. Objective: Accurate experimental measurement of these near-field blast events, using intrusive methods, is demanding owing to the high magnitudes (> 100 MPa) and short durations (< 1 ms) of loading. The objective of this article is to develop a non-intrusive method for measuring reflected blast pressure distributions using image analysis. Methods: This article presents results from high speed video analysis of near-field spherical PE4 explosive blasts. The Canny edge detection algorithm is used to track the outer surface of the explosive fireball, with the results used to derive a velocity-radius relationship. Reflected pressure distributions are calculated using this velocity-radius relationship in conjunction with the Rankine-Hugoniot jump conditions. Results: The indirectly measured pressure distributions from high speed video are compared with directly measured pressure distributions and are shown to be in good qualitative agreement with respect to distribution of reflected pressures, and in good quantitative agreement with peak reflected pressures (within 10% of the maximum recorded value). Conclusions: The results indicate that it is possible to accurately measure blast loads in the order of 100s MPa using techniques which do not require sensitive recording equipment to be located close to the source of the explosion