Biblio

With the rapid development of mobile internet, mobile devices are requiring more complex authorization policy to ensure an secure access control on mobile data. However mobiles have limited resources (computing, storage, etc.) and are not suitable to execute complex operations. Cloud computing is an increasingly popular paradigm for accessing powerful computing resources. Intuitively we can solve that problem by moving the complex access control process to the cloud and implement a fine-grained access control relying on the powerful cloud. However the cloud computation may not be trusted, a crucial problem is how to verify the correctness of such computations. In this paper, we proposed a public verifiable cloud access control scheme based on Parno's public verifiable computation protocol. For the first time, we proposed the conception and concrete construction of verifiable cloud access control. Specifically, we firstly design a user private key revocable Key Policy Attribute Based Encryption (KP-ABE) scheme with non-monotonic access structure, which can be combined with the XACML policy perfectly. Secondly we convert the XACML policy into the access structure of KP-ABE. Finally we construct a security provable public verifiable cloud access control scheme based on the KP-ABE scheme we designed.

Many modern business models of the manufacturing industry use the possibilities of digitization. In particular, the idea of connecting machines to networks and communication infrastructure is gaining momentum. However, in addition to the considerable economic advantages, this development also brings decisive disadvantages. By connecting previously encapsulated industrial networks with untrustworthy external networks such as the Internet, machines and systems are suddenly exposed to the same threats as conventional IT systems. A key problem today is the typical network paradigm with static routers and switches that cannot meet the dynamic requirements of a modern industrial network. Current security solutions often only threat symptoms instead of tackling the cause. In this paper we will therefore analyze the weaknesses of current networks and security solutions using the example of industrial remote maintenance. We will then present a novel concept of how Software-Defined Networking (SDN) in combination with a policy framework that supports attribute-based access control can be used to meet current and future security requirements in dynamic industrial networks. Furthermore, we will introduce an examplary implementation of this novel security framework for the use case of industrial remote maintenance and evaluate the solution. Our results show that SDN in combination with an Attribute-based Access Control (ABAC) policy framework is perfectly suited to increase flexibility and security of modern industrial networks at the same time.

In context-aware applications, user's access privileges rely on both user's identity and context. Access control rules are usually statically defined while contexts and the system state can change dynamically. Changes in contexts can result in service disruptions. To address this issue, this poster proposes a reactive access control system that associates contingency plans with access control rules. Risk scores are also associated with actions part of the contingency plans. Such risks are estimated by using fuzzy inference. Our approach is cast into the XACML reference architecture.

While the standard language XACML is very expressive for specifying fine-grained access control policies, defects can get into XACML policies for various reasons, such as misunderstanding of access control requirements, omissions, and coding errors. These defects may result in unauthorized accesses, escalation of privileges, and denial of service. Therefore, quality assurance of XACML policies for real-world information systems has become an important issue. To address this issue, this paper presents a family of coverage criteria for XACML policies, such as rule coverage, rule pair coverage, decision coverage, and Modified Condition/Decision Coverage (MC/DC). To demonstrate the assurance levels of these coverage criteria, we have developed methods for automatically generating tests, i.e., access requests, to satisfy the coverage criteria using a constraint solver. We have evaluated these methods through mutation analysis of various policies with different levels of complexity. The experiment results have shown that the rule coverage is far from adequate for revealing the majority of defects in XACML policies, and that both MC/DC and decision coverage tests have outperformed the existing methods for testing XACML policies. In particular, MC/DC tests achieve a very high level of quality assurance of XACML policies.

Nowadays Big data is considered as one of the major technologies used to manage a huge number of data, but there is little consideration of privacy in big data platforms. Indeed, developers don't focus on implementing security best practices in their programs to protect personal and sensitive data, and organizations can face financial lost because of this noncompliance with applied regulations. In this paper, we propose a solution to insert privacy policies written in XACML (eXtensible Access Control Markup Language) in access control solution to NoSQL database, our solution can be used for NoSQL data store which doesn't t include many access control features, it aims basically to ensure fine grained access control considering purpose as the main parameter, we will focus on access control in document level, and apply this approach to MongoDB which is the most used NoSQL data store.

Mobile application offloading, with the purpose of extending battery lifetime and increasing performance has been intensively discussed recently, resulting in various different solutions: mobile device clones operated as virtual machines in the cloud, simultaneously running applications on the mobile device and on a distant server, as well as flexible solutions dynamically acquiring other mobile devices' resources in the user's surrounding. Existing solutions have gaps in the fields of data security and application security. These gaps can be closed by integrating data usage policies, as well as application-flow policies. In this paper, we propose and evaluate a novel approach of integrating XACML into existing mobile application offloading-frameworks. Data owners remain in full control of their data, still, technologies like device-to-device offloading can be used.

In distributed systems, there is often a need to combine the heterogeneous access control policies to offer more comprehensive services to users in the local or national level. A large scale healthcare system is usually distributed in a computer network and might require sophisticated access control policies to protect the system. Therefore, the need for integrating the electronic healthcare systems might be important to provide a comprehensive care for patients while preserving patients' privacy and data security. However, there are major impediments in healthcare systems concerning not well-defined and flexible access control policy implementations, hindering the progress towards secure integrated systems. In this paper, we introduce an access control policy combination framework for EHR systems that preserves patients' privacy and ensures data security. We achieve our goal through an access control mechanism which handles multiple access control policies through a similarity analysis phase. In that phase, we evaluate different XACML policies to decide whether or not a policy combination is applicable. We have provided a case study to show the applicability of our proposed approach based on XACML. Our study results can be applied to the electronic health record (EHR) access control policy, which fosters interoperability and scalability among healthcare providers while preserving patients' privacy and data security. 

We describe the formalization of a correctness proof for a conflict detection algorithm for XACML (eXtensible Access Control Markup Language). XACML is a standardized declarative access control policy language that is increasingly used in industry. In practice it is common for rule sets to grow large, and contain unintended errors, often due to conflicting rules. A conflict occurs in a policy when one rule permits a request and another denies that same request. Such errors can lead to serious risks involving both allowing access to an unauthorized user as well as denying access to someone who needs it. Removing conflicts is thus an important aspect of debugging policies, and the use of a verified algorithm provides the highest assurance in a domain where security is important. In this paper, we focus on several complex XACML constructs, including time ranges and integer intervals, as well as ways to combine any number of functions using the boolean operators and, or, and not. The latter are the most complex, and add significant expressive power to the language. We propose an algorithm to find conflicts and then use the Coq Proof Assistant to prove the algorithm correct. We develop a library of tactics to help automate the proof.

In international military coalitions, situation awareness is achieved by gathering critical intel from different authorities. Authorities want to retain control over their data, as they are sensitive by nature, and, thus, usually employ their own authorization solutions to regulate access to them. In this paper, we highlight that harmonizing authorization solutions at the coalition level raises many challenges. We demonstrate how we address authorization challenges in the context of a scenario defined by military experts using a prototype implementation of SAFAX, an XACML-based architectural framework tailored to the development of authorization services for distributed systems.

The American National Standards Institute (ANSI) has standardized an access control approach, Next Generation Access Control (NGAC), that enables simultaneous instantiation of multiple access control policies. For large complex enterprises this is critical to limiting the authorized access of insiders. However, the specifications describe the required access control capabilities but not the related algorithms. While appropriate, this leave open the important question as to whether or not NGAC is scalable. Existing cubic reference implementations indicate that it does not. For example, the primary NGAC reference implementation took several minutes to simply display the set of files accessible to a user on a moderately sized system. To solve this problem we provide an efficient access control decision algorithm, reducing the overall complexity from cubic to linear. Our other major contribution is to provide a novel mechanism for administrators and users to review allowed access rights. We provide an interface that appears to be a simple file directory hierarchy but in reality is an automatically generated structure abstracted from the underlying access control graph that works with any set of simultaneously instantiated access control policies. Our work thus provides the first efficient implementation of NGAC while enabling user privilege review through a novel visualization approach. These capabilities help limit insider access to information (and thereby limit information leakage) by enabling the efficient simultaneous instantiation of multiple access control policies.