Web-based applications greatly increase information availability and ease of access, which is optimal for public information. The distribution and sharing of information via the Web that must be accessed in a selective way, such as electronic commerce transactions, require the definition and enforcement of security controls, ensuring that information will be accessible only to authorized entities. Different approaches have been proposed that address the problem of protecting information in a Web system. However, these approaches typically operate at the file-system level, independently of the data that have to be protected from unauthorized accesses. Part of this problem is due to the limitations of HTML, historically used to design Web documents. The extensible markup language (XML), a markup language promoted by the World Wide Web Consortium (W3C), is de facto the standard language for the exchange of information on the Internet and represents an important opportunity to provide fine-grained access control. We present an access control model to protect information distributed on the Web that, by exploiting XML's own capabilities, allows the definition and enforcement of access restrictions directly on the structure and content of the documents. We present a language for the specification of access restrictions, which uses standard notations and concepts, together with a description of a system architecture for access control enforcement based on existing technology. The result is a flexible and powerful security system offering a simple integration with current solutions.

Abstract. Access control is the process of mediating every request to resources and data maintained by a system and determining whether the request should be granted or denied. The access control decision is enforced by a mechanism implementing regulations established by a security policy. Different access control policies can be applied, corresponding to different criteria for defining what should, and what should not, be allowed, and, in some sense, to different definitions of what ensuring security means. In this chapter we investigate the basic concepts behind access control design and enforcement, and point out different security requirements that may need to be taken into consideration. We discuss several access control policies, and models formalizing them, that have been proposed in the literature or that are currently under investigation.

The impact of privacy requirements in the development of modern applications is increasing very quickly. Many commercial and legal regulations are driving the need to develop reliable solutions for protecting sensitive information whenever it is stored, processed, or communicated to external parties. To this purpose, encryption techniques are currently used in many scenarios where data protection is required since they provide a layer of protection against the disclosure of personal information, which safeguards companies from the costs that may arise from exposing their data to privacy breaches. However, dealing with encrypted data may make query processing more expensive.In this article, we address these issues by proposing a solution to enforce the privacy of data collections that combines data fragmentation with encryption. We model privacy requirements as confidentiality constraints expressing the sensitivity of attributes and their associations. We then This article extends the previous work by the authors appeared under the title Fragmentation and Encryption to Enforce Privacy in Data Storage in 22:2 • V. Ciriani et al.use encryption as an underlying (conveniently available) measure for making data unintelligible while exploiting fragmentation as a way to break sensitive associations among attributes. We formalize the problem of minimizing the impact of fragmentation in terms of number of fragments and their affinity and present two heuristic algorithms for solving such problems. We also discuss experimental results, comparing the solutions returned by our heuristics with respect to optimal solutions, which show that the heuristics, while guaranteeing a polynomial-time computation cost are able to retrieve solutions close to optimum.

Abstract. The widespread adoption of mobile communication devices combined with technical improvements of location technologies are fostering the development of a new wave of applications that manage physical positions of individuals to offer location-based services for business, social or informational purposes. As an effect of such innovative services, however, privacy concerns are increasing, calling for more sophisticated solutions for providing users with different and manageable levels of privacy. In this work, we propose a way to express users privacy preferences on location information in a straightforward and intuitive way. Then, based on such location privacy preferences, we discuss a new solution, based on obfuscation techniques, which permits us to achieve, and quantitatively estimate through a metric, different degrees of location privacy.

The Cloud computing paradigm has revolutionised the computer science horizon during the past decade and has enabled the emergence of computing as the fifth utility. It has captured significant attention of academia, industries, and government bodies. Now, it has emerged as the backbone of modern economy by offering subscription-based services anytime, anywhere following a pay-as-you-go model. This has instigated (1) shorter establishment times for start-ups, (2) creation of scalable global enterprise applications, (3) better cost-to-value associativity for scientific and high performance computing applications, and (4) different invocation/execution models for pervasive and ubiquitous applications. The recent technological developments and paradigms such as serverless computing, software-defined networking, Internet of Things, and processing at network edge are creating new opportunities for Cloud computing. However, they are also posing several new challenges and creating the need for new approaches and research strategies, as well as the re-evaluation of the models that were developed to * Corresponding