Privacy-Preserving Trust Management Mechanisms from Private Matching Schemes

Cryptographic primitives are essential for constructing privacy-preserving communication mechanisms. There are situations in which two parties that do not know each other need to exchange sensitive information on the Internet. Trust management mechanisms make use of digital credentials and certificates in order to establish trust among these strangers. We address the problem of choosing which credentials are exchanged. During this process, each party should learn no information about the preferences of the other party other than strictly required for trust establishment. We present a method to reach an agreement on the credentials to be exchanged that preserves the privacy of the parties. Our method is based on secure two-party computation protocols for set intersection. Namely, it is constructed from private matching schemes.Comment: The material in this paper will be presented in part at the 8th DPM International Workshop on Data Privacy Management (DPM 2013

AUTOMATED TRUST NEGOTIATION USING CRYPTOGRAPHIC CREDENTIALS

In automated trust negotiation (ATN), two parties exchange digitally signed credentials that contain attribute information to establish trust and make access control decisions. Because the information in question is often sensitive, credentials are protected according to access control policies. In traditional ATN, credentials are transmitted either in their entirety or not at all. This approach can at times fail unnecessarily, either because a cyclic dependency makes neither negotiator willing to reveal her credential before her opponent, because the opponent must be authorized for all attributes packaged together in a credential to receive any of them, or because it is necessary to fully disclose the attributes, rather than merely proving they satisfy some predicate (such as being over 21 years of age). Recently, several cryptographic credential schemes and associated protocols have been developed to address these and other problems. However, they can be used only as fragments of an ATN process. This paper introduces a framework for ATN in which the diverse credential schemes and protocols can be combined, integrated, and used as needed. A policy language is introduced that enables negotiators to specify authorization requirements that must be met by an opponent to receive various amounts of information about certified attributes and the credentials that contain it. The language also supports the use of uncertified attributes, allowing them to be required as part of policy satisfaction, and to place their (automatic) disclosure under policy control

An investigation of interoperability issues between authorisation systems within web services

The existing authorisation systems within the context of Web Services mainly apply two access control approaches – Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC). The RBAC approach links an authenticated Web Service Requester to its specific access control permission through roles, but RBAC is not flexible enough to cater for some cases where extra attribute information is needed in addition to the identity. By contrast, the ABAC approach has more flexibility, as it allows a Web Service Requester to submit necessary credentials containing extra attribute information that can fulfil the policies declared by a Web Service Provider, which aims to protect the sensitive resources/services.RBAC and ABAC can only help to establish a unilateral trust relationship between two Web Services to enable a Web Service Provider to make an access control decision. Unfortunately, the nature of Web Services presents a high probability that two Web Services may not know each other. Therefore, successful authorisation may fail, if the Web Service Requester does not trust the Web Service Provider.Trust Negotiation (TN) is also an access control approach, which can provide a bilateral trust relationship between two unknown entities, so it sometimes can enable authorisation success in situations where success is not possible through RBAC or ABAC approaches. However, interoperability issues will arise between authorisation systems within Web Services, where a bilateral trust-based authorisation solution is applied. In addition, a lack of a unified approach that can address the interoperability issues remains as a research problem. This research aims to explore possible factors causing the lack of interoperability first, and then to explore an approach that can address the interoperability issues. The main contributions of this research are an improved interoperability model illustrating interoperability issues at different layers of abstraction, and a novel interoperability-solution design along with an improved TN protocol as an example of utilising this design to provide interoperability between authorisation systems within Web Services

Hidden assumptions, attitudes, and procedures in failing schools

Describes the different assumptions and ingrained habits used in education that are observed to impede learning in schools. Accepted ManuscriptGunzelmann, B. (2008). Hidden Assumptions, Attitudes, and Procedures in Failing Schools. Educational Horizons 86(2), 85-97

Advanced languages and techniques for trust negotiation.

The Web is quickly shifting from a document browsing and delivery system to a hugely complex ecosystem of interconnected online applications. A relevant portion of these applications dramatically increase the number of users required to dynamically authenticate themselves and to, on the other hand, to identify the service they want to use. In order to manage interactions among such users/services is required a flexible but powerful mechanism. Trust management, and in particular trust negotiation techniques, is a reasonable solution. In this work we present the formalization of the well known trust negotiation framework Trust-X, of a rule-based policy definition language, called X-RNL. Moreover, we present the extension of both the framework and of the language to provide advanced trust negotiation architectures, namely negotiations among groups. We also provide protocols to adapt trust negotiations to mobile environments, specifically, we present protocols allowing a trust negotiation to be executed among several, distinct, sessions while still preserving its security properties. Such protocols have also been extended to provides the capability to migrate a ongoing trust negotiation among a set of known, reliable, subjects. Finally, we present the application of the previously introduced trust negotiation techniques into real world scenarios: online social networks, critical infrastructures and cognitive radio networks

Sybil attacks against mobile users: friends and foes to the rescue

Collaborative applications for co-located mobile users can be severely disrupted by a sybil attack to the point of being unusable. Existing decentralized defences have largely been designed for peer-to-peer networks but not for mobile networks. That is why we propose a new decentralized defence for portable devices and call it MobID. The idea is that a device manages two small networks in which it stores information about the devices it meets: its network of friends contains honest devices, and its network of foes contains suspicious devices. By reasoning on these two networks, the device is then able to determine whether an unknown individual is carrying out a sybil attack or not. We evaluate the extent to which MobID reduces the number of interactions with sybil attackers and consequently enables collaborative applications.We do so using real mobility and social network data. We also assess computational and communication costs of MobID on mobile phones

Opportunistic Sensing: Security Challenges for the New Paradigm

We study the security challenges that arise in Opportunistic people-centric sensing, a new sensing paradigm leveraging humans as part of the sensing infrastructure. Most prior sensor-network research has focused on collecting and processing environmental data using a static topology and an application-aware infrastructure, whereas opportunistic sensing involves collecting, storing, processing and fusing large volumes of data related to everyday human activities. This highly dynamic and mobile setting, where humans are the central focus, presents new challenges for information security, because data originates from sensors carried by people— not tiny sensors thrown in the forest or attached to animals. In this paper we aim to instigate discussion of this critical issue, because opportunistic people-centric sensing will never succeed without adequate provisions for security and privacy. To that end, we outline several important challenges and suggest general solutions that hold promise in this new sensing paradigm

Proceedings of the 2nd International Workshop on Security in Mobile Multiagent Systems

This report contains the Proceedings of the Second Workshop on Security on Security of Mobile Multiagent Systems (SEMAS2002). The Workshop was held in Montreal, Canada as a satellite event to the 5th International Conference on Autonomous Agents in 2001. The far reaching influence of the Internet has resulted in an increased interest in agent technologies, which are poised to play a key role in the implementation of successful Internet and WWW-based applications in the future. While there is still considerable hype concerning agent technologies, there is also an increasing awareness of the problems involved. In particular, that these applications will not be successful unless security issues can be adequately handled. Although there is a large body of work on cryptographic techniques that provide basic building-blocks to solve specific security problems, relatively little work has been done in investigating security in the multiagent system context. Related problems are secure communication between agents, implementation of trust models/authentication procedures or even reflections of agents on security mechanisms. The introduction of mobile software agents significantly increases the risks involved in Internet and WWW-based applications. For example, if we allow agents to enter our hosts or private networks, we must offer the agents a platform so that they can execute correctly but at the same time ensure that they will not have deleterious effects on our hosts or any other agents / processes in our network. If we send out mobile agents, we should also be able to provide guarantees about specific aspects of their behaviour, i.e., we are not only interested in whether the agents carry out-out their intended task correctly. They must defend themselves against attacks initiated by other agents, and survive in potentially malicious environments. Agent technologies can also be used to support network security. For example in the context of intrusion detection, intelligent guardian agents may be used to analyse the behaviour of agents on a firewall or intelligent monitoring agents can be used to analyse the behaviour of agents migrating through a network. Part of the inspiration for such multi-agent systems comes from primitive animal behaviour, such as that of guardian ants protecting their hill or from biological immune systems