Andrea Perego

Enforcing access control in Web-based social networks

In this article, we propose an access control mechanism for Web-based social networks, which adopts a rule-based approach for specifying access policies on the resources owned by network participants, and where authorized users are denoted in terms of the type, depth, and trust level of the relationships existing between nodes in the network. Different from traditional access control systems, our mechanism makes use of a semidecentralized architecture, where access control enforcement is carried out client-side. Access to a resource is granted when the requestor is able to demonstrate being authorized to do that by providing a proof. In the article, besides illustrating the main notions on which our access control model relies, we present all the protocols underlying our system and a performance study of the implemented prototype.

A Decentralized Security Framework for Web-Based Social Networks

The wide diffusion and usage of social networking Web sites in the last years have made publicly available a huge amount of possible sensitive information, which can be used by third-parties with purposes different from the ones of the owners of such information. Currently, this issue has been addressed by enforcing into Web-based Social Networks (WBSNs) very simple protection mechanisms, or by using anonymization techniques, thanks to which it is possible to hide the identity of WBSN members while performing analysis on social network data. However, we believe that further solutions are needed, to allow WBSN members themselves to decide who can access their personal information and resources. To cope with this issue, in this article we illustrate a decentralized security framework for WBSNs, which provide both access control and privacy protection mechanisms. In our system, WBSN members can denote who is authorized to access the resources they publish and the relationships they participate in, in terms of the type, depth, and trust level of the relationships existing between members of a WBSN. Cryptographic techniques are then used to provide a controlled sharing of resources while preserving relationship privacy.

Combining Social Networks and Semantic Web Technologies for Personalizing Web Access

The original purpose of Web metadata was to protect end-users from possible harmful content and to simplify search and retrieval. However they can also be also exploited in more enhanced applications, such as Web access personalization on the basis of end-users’ preferences. In order to achieve this, it is however necessary to address several issues. One of the most relevant is how to assess the trustworthiness of Web metadata. In this paper, we discuss how such issue can be addressed through the use of collaborative and Semantic Web technologies. The system we propose is based on a Web-based Social Network, where members are able not only to specify labels, but also to rate existing labels. Both labels and ratings are then used to assess the trustworthiness of resources’ descriptions and to enforce Web access personalization.

A General Framework for Web Content Filtering

Web content filtering is a means to make end-users aware of the ‘quality’ of Web resources by evaluating their contents and/or characteristics against users’ preferences. Although they can be used for a variety of purposes, Web content filtering tools are mainly deployed as a service for parental control purposes, and for regulating the access to Web content by users connected to the networks of enterprises, libraries, schools, etc. Current Web filtering tools are based on well established techniques, such as data mining and firewall blocking, and they typically cater to the filtering requirements of very specific end-user categories. Therefore, what is lacking is a unified filtering framework able to support all the possible application domains, and making it possible to enforce interoperability among the different filtering approaches and the systems based on them. In this paper, a multi-strategy approach is described, which integrates the available techniques and focuses on the use of metadata for rating and filtering Web information. Such an approach consists of a filtering meta-model, referred to as MFM (Multi-strategy Filtering Model), which provides a general representation of the Web content filtering domain, independently from its possible applications, and of two prototype implementations, partially carried out in the framework of the EU projects EUFORBIA and QUATRO, and designed for different application domains: user protection and Web quality assurance, respectively.

MaX: an access control system for digital libraries and the Web

Digital libraries (DLs) introduce several challenging requirements with respect to the formulation, specification and enforcement of adequate access control policies. Unlike conventional database environments, a DL typically is characterised by a dynamic subject population, often making accesses from remote locations, and by an extraordinarily large amount of information, stored in a variety of formats. Additionally, protecting a DL does not only mean protecting documents that reside at the DL site, but also protecting accesses that the DL subscribers made to external Web documents. We present MaX, a comprehensive system for enforcing access control, specifically tailored to both DL and Web environments. Key features of MaX are the support for credential and content-based access control to DL and Web documents, and its full integration with standard Internet rating systems.

Content-based filtering of Web documents: the MaX system and the EUFORBIA project

Internet filtering has particular requirements which traditional access control approaches cannot satisfy. In this paper, we present a multi-strategy filtering model tailored specifically to both digital library and Web environments whose key features are the support for credential and content-based filtering and its full integration with standard Internet rating systems. Moreover, we describe the prototype system implementing our model and developed in the framework of the European project EUFORBIA.

The Quality Social Network: A collaborative environment for personalizing Web access

In this paper, we present a collaborative social networking environment, referred to as Quality Social Network (QSN), which enhances the social tagging paradigm by using it as a basis to evaluate the quality of Web resources, on the basis of the user preferences specified by each QSN member. Such features give end users the ability of being aware of the “quality” of the resources they are accessing, based on the opinions of the members of their community, and of being informed whether such resources can be safely used, according to the requirements specified by end users themselves. Besides illustrating the main characteristics of the QSN and its architecture, we describe its prototype implementation, carried out in the framework of the QUATRO Plus EU project, and its application to a use case scenario, involving groups of teenagers from three different European countries, acting as Youth Panels of the Safer Internet EU Programme.

An Access Control System for Digital Libraries and the Web: The MaX Prototype Demonstration

The goal of this demonstration is to present the main features of MaX,a system enforcing access control to Web documents.This system has been developed at the Dipartimento di Scienze dell’Informazione of the University of Milano in the framework of the European project EUFORBIA, and implements the Milano Model, an access control mechanism conceived for Digital Library (DL)and Web environments.