1,720,969 research outputs found
Access Control for the Pepys Internet-Wide File-System
No full textThis paper describes the Access Control Model realized for the novel Pepys distributed, Internet-wide, file-system. The model design has been widely inspired to various existing standards and best practices about access control and security in file-system access, but it also echoes peculiar basic principles characterizing the design of Pepys, as well as the ΠP protocol, over which Pepys itself relies. The paper also provides technical details about how the model has been realized on a Linux port of Pepys
Smartphone-based crowdsourcing for estimating the bottleneck capacity in wireless networks
Get PDFCrowdsourcing enables the fine-grained characterization and performance evaluation of today׳s large-scale networks using the power of the masses and distributed intelligence. This paper presents SmartProbe, a system that assesses the bottleneck capacity of Internet paths using smartphones, from a mobile crowdsourcing perspective. With SmartProbe measurement activities are more bandwidth efficient compared to similar systems, and a larger number of users can be supported. An application based on SmartProbe is also presented: georeferenced measurements are mapped and used to compare the performance of mobile broadband operators in wide areas. Results from one year of operation are included
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Analyzing and Securing Firmware for IoT Devices
Get PDFInternet of Things (IoT) devices have rooted themselves in the everyday life of billions of people. While they automate and simplify many aspects of the users’ lives, the widespread usage of IoT devices constitutes a security concern for our modern society. Aside from the privacy and safety implications of having a smart door lock that could succumb to an Internet-based attack, or a smoke detector that an assailant could disable by connecting to it from a compromised light bulb, vulnerabilities in these devices have wider implications. Recent large-scale attacks have shown that the sheer number of Internet-connected IoT devices poses a severe threat to the Internet infrastructure. The most prominent example is represented by the Mirai botnet that, in 2016, compromised millions of devices and leveraged them in denial-of-service attacks to disrupt core Internet services and shut down websites. For these reasons, it is of crucial importance to assess the security of IoT devices. Analyzing and securing IoT devices present different and specific challenges than analyzing and securing traditional desktop computers. The main reason is that IoT devices are manufactured by a plethora of different vendors, which often use vendor-specific hardware and software (or firmware) for their products. Given the heterogeneity and widespread usage of IoT devices, we need novel, automated, and scalable solutions able to improve the security of these devices. During my Ph.D., I approached the problem of securing IoT devices from different angles and using different strategies, which I present in detail in this dissertation. First, I introduce the IoT landscape, with particular attention to the peculiarities that characterize embedded firmware. Then, I present in detail my work that advances the state of the art of firmware security. In particular, I present (i) BootStomp, a novel tool to find bugs in bootloaders for embedded devices, (ii) Karonte, a novel static analysis approach to track data flows across the different components of a firmware sample to precisely uncover security vulnerabilities, (iii) Bintrimmer, a tool that relies on a novel abstract domain (called Signedness-Agnostic Strided Interval) to perform code debloating on binaries, thus decreasing the attack surface that could be used by an attacker to harm end-users, and, finally, (iv) DiAne, a novel approach to fuzz IoT devices that leverages the logic of the device’s companion app (i.e., the application commonly used to interact with IoT devices). I evaluate the performance of the proposed approaches and show that the developed tools are effective in improving the security of firmware for IoT devices
Access control in distributed file systems: design and realization on Pepys fs
No full textThis theis describes the Access Control Model realized for the novel Pepys distributed, Internet-wide, file-system.
The model design has been widely inspired to various existing standards and best practices about access control and security in file-system access, but it also echoes peculiar basic principles characterizing the design of Pepys, as well as the ΠP protocol, over which Pepys itself relies. Technical details about how the model has been realized on a Linux port of Pepys are also provided
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
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