Luca Costabello

Context-aware access control for RDF graph stores

We present SHI3LD, an access control framework for RDF stores. Our solution supports access from mobile devices with context-aware policies and is exclusively grounded on standard Semantic Web languages. Designed as a pluggable filter for generic SPARQL endpoints, the module uses RDF named graphs and SPARQL to protect triples. Evaluation shows faster execution time for low-selective queries and less impact on larger datastores.

DC proposal: PRISSMA, towards mobile adaptive presentation of the web of data

The Mobile Web is evolving fast and mobile access to the Web of Data is gaining momentum. Interlinked RDF resources consumed from portable devices need proper adaptation to the context in which the action is performed. This paper introduces PRISSMA (Presentation of Resources for Interoperable Semantic and Shareable Mobile Adaptability), a domain-independent vocabulary for displaying Web of Data resources in mobile environments. The vocabulary is the first step towards a declarative framework aimed at sharing and re-using presentation information for context-adaptable user interfaces over RDF data.

A Social Semantic Web Access Control Model

In the Social Web, the users are invited to publish a lot of personal information. These data can be easily retrieved, and sometimes reused, without providing the users with fine-grained access control mechanisms able to restrict the access to their profiles, and data. In this paper, we present an access control model for the Social Semantic Web. Our model is grounded on the Social Semantic SPARQL Security for Access Control vocabulary (S4AC). This vocabulary can be used by the users to define their own terms of access to the data. We define an algorithm, implemented in our Access Control Manager, which allows to check, after a client query, to which extent the data are available, depending on the user’s profile. The evaluation of the access conditions is related to different features, such as the social tags associated with the data, and the user’s contextual information, such as being part of a group, being located in a specific place. We provide an evaluation of the overhead introduced by our Access Control Manager, and we show that access control in the Social Semantic Web comes with a cost, but this is acceptable given the benefits of data protection.

Access Control for HTTP Operations on Linked Data

Access control is a recognized open issue when interacting with RDF using HTTP methods. In literature, authentication and authorization mechanisms either introduce undesired complexity such as SPARQL and ad-hoc policy languages, or rely on basic access control lists, thus resulting in limited policy expressiveness. In this paper we show how the Shi3ld attribute-based authorization framework for SPARQL endpoints has been progressively converted to protect HTTP operations on RDF. We proceed by steps: we start by supporting the SPARQL 1.1 Graph Store Protocol, and we shift towards a SPARQL-less solution for the Linked Data Platform. We demonstrate that the resulting authorization framework provides the same functionalities of its SPARQL-based counterpart, including the adoption of Semantic Web languages only.

Ubiquitous access control for SPARQL endpoints: lessons learned and future challenges

We present and evaluate a context-aware access control framework for SPARQL endpoints queried from mobile.

SHI3LD: an access control framework for the mobile web of data

We present Shi3ld, a context-aware access control framework for consuming the Web of Data from mobile devices.

Error-Tolerant RDF Subgraph Matching for Adaptive Presentation of Linked Data on Mobile

We present PRISSMA, a context-aware presentation layer for Linked Data. PRISSMA extends the Fresnel vocabulary with the notion of mobile context. Besides, it includes an algorithm that determines whether the sensed context is compatible with some context declarations. The algorithm finds optimal error-tolerant subgraph isomorphisms between RDF graphs using the notion of graph edit distance and is sublinear in the number of context declarations in the system.

Adaptive presentation of linked data on mobile

We present PRISSMA, a context-aware presentation layer for Linked Data. PRISSMA extends the Fresnel vocabulary with the notion of mobile context. Besides, it includes an algorithm that determines whether the sensed context is compatible with some context declarations.

Context-Aware Presentation of Linked Data on Mobile

In this paper the authors focus on context-aware adaptation for linked data on mobile. They split up the problem in two sub-questions: how to declaratively describe context at RDF presentation level, and how to overcome context imprecisions and incompleteness when selecting the proper context description at runtime. The authors answer their two-fold research question with PRISSMA, a context-aware presentation layer for Linked Data. PRISSMA extends the Fresnel vocabulary with the notion of mobile context. Besides, it includes an algorithm that determines whether the sensed context is compatible with some context declarations. The algorithm finds optimal error-tolerant subgraph isomorphisms between RDF graphs using the notion of graph edit distance and is sublinear in the number of context declarations in the system.

Social Semantic Network-Based Access Control

Social networks are the bases of the so-called Web 2.0, raising many new challenges to the research community. In particular, the ability of these networks to allow the users to share their own personal information with other people opens new issues concerning privacy and access control. Nowadays the Web has further evolved into the Social Semantic Web where social networks are integrated and enhanced by the use of semantic conceptual models, e.g., the ontologies, where the social information and links among the users become semantic information and links. In this chapter, we discuss which are the benefits of introducing semantics in social network-based access control. In particular, we analyze and detail two approaches to manage the access rights of the social network users relying on Semantic Web languages only, and we highlight, thanks to these two proposals, what are pros and cons of introducing semantics in social networks access control. Finally, we report on the other existing approaches coupling semantics and access control in the context of social networks.