1,721,037 research outputs found
Reasoning about Security in Mobile Ambients
No full textThe paper gives an assessment of security for Mobile Ambients, with specific focus on mandatory access control (MAC) policies in multilevel security systems. The first part of the paper reports on different formalization attempts for MAC policies in the Ambient Calculus, and provides an in-depth analysis of the problems one encounters. As it turns out, MAC security does not appear to have fully convincing interpretations in the calculus. The second part proposes a solution to this impasse, based on a variant of Mobile Ambients. A type system for resource access control is defined, and the new calculus is discussed and illustrated with several examples of resource management policies
Name-passing calculi and crypto-primitives: A survey
No full textThe paper surveys the literature on high-level name-passing process calculi, and their extensions with cryptographic primitives. The survey is by no means exhaustive, for essentially two reasons. First, in trying to provide a coherent presentation of different ideas and techniques, one inevitably ends up leaving out the approaches that do not fit the intended roadmap. Secondly, the literature on the subject has been growing at very high rate over the years. As a consequence, we decided to concentrate on few papers that introduce the main ideas, in the hope that discussing them in some detail will provide sufficient insight for further reading
Testing for Integrity Flaws in Web Sessions
No full textWeb sessions are fragile and can be attacked at many different levels. Classic attacks like session hijacking, session fixation and cross-site request forgery are particularly dangerous for web session security, because they allow the attacker to breach the integrity of honest users’ sessions by forging requests which get authenticated on the victim’s behalf. In this paper, we systematize current countermeasures against these attacks and the shortcomings thereof, which may completely void protection under specific assumptions on the attacker’s capabilities. We then build on our security analysis to introduce black-box testing strategies to discover insecure session implementation practices on existing websites, which we implement in a browser extension called Dredd. Finally, we use Dredd to assess the security of 20 popular websites from Alexa, exposing a number of session integrity flaws
Secrecy in Untrusted Networks
No full textWe investigate the protection of migrating agents against the untrusted sites they traverse. The resulting calculus provides a formal framework to reason about protection policies and security protocols over distributed, mobile infrastructures, and aims to stand to ambients as the spi calculus stands to ?. We present a type system that separates trusted and untrusted data and code, while allowing safe interactions with untrusted sites. We prove that the type system enforces a privacy property, and show the expressiveness of the calculus via examples and an encoding of the spi calculus
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Information Flow Security in Boxed Ambients
No full textWe study the problem of secure information flow for Boxed Ambients in terms of noninterference. We develop a sound type system that provides static guarantees of absence of unwanted flow of information for well typed processes. Non-interference is stated, and proved, in terms of a typed notion of contextual equivalence for Boxed Ambients akin to the corresponding equivalence defined for Mobile Ambients
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