Privacy in Mobile Agent Systems: Untraceability

Agent based Internet environments are an interesting alternative to existing approaches of building software systems. The enabling feature of agents is that they allow software development based on the abstraction (a "metaphor") of elements of the real world. In other words, they allow building software systems, which work as human societies, in which members share products and services, cooperate or compete with each other. Organisational, behavioural and functional models etc applied into the systems can be copied from the real world. The growing interest in agent technologies in the European Union was expressed through the foundation of the Coordination Action for Agent-Based Computing, funded under the European Commission's Sixth Framework Programme (FP6). The action, called AgentLink III is run by the Information Society Technologies (IST) programme. The long-term goal of AgentLink is to put Europe at the leading edge of international competitiveness in this increasingly important area. According to AgentLink "Roadmap for Agent Based Computing"; agent-based systems are perceived as "one of the most vibrant and important areas of research and development to have emerged in information technology in recent years, underpinning many aspects of broader information society technologies"; However, with the emergence of the new paradigm, came also new challenges. One of them is that agent environments, especially those which allow for mobility of agents, are much more difficult to protect from intruders than conventional systems. Agent environments still lack sufficient and effective solutions to assure their security. The problem which till now has not been addressed sufficiently in agent-based systems is privacy, and particularly the anonymity of agent users. Although anonymity was studied extensively for traditional message-based communication for which during the past twenty five years various techniques have been proposed, for agent systems this problem has never been directly addressed. The research presented in this report aimed at filling this gap. This report summarises results of studies aiming at the identification of threats to privacy in agent-based systems and the methods of their protection.JRC.G.6-Sensors, radar technologies and cybersecurit

Anonymity and Information Hiding in Multiagent Systems

We provide a framework for reasoning about information-hiding requirements in multiagent systems and for reasoning about anonymity in particular. Our framework employs the modal logic of knowledge within the context of the runs and systems framework, much in the spirit of our earlier work on secrecy [Halpern and O'Neill 2002]. We give several definitions of anonymity with respect to agents, actions, and observers in multiagent systems, and we relate our definitions of anonymity to other definitions of information hiding, such as secrecy. We also give probabilistic definitions of anonymity that are able to quantify an observer s uncertainty about the state of the system. Finally, we relate our definitions of anonymity to other formalizations of anonymity and information hiding, including definitions of anonymity in the process algebra CSP and definitions of information hiding using function views.Comment: Replacement. 36 pages. Full version of CSFW '03 paper, submitted to JCS. Made substantial changes to Section 6; added references throughou

How to Work with Honest but Curious Judges? (Preliminary Report)

The three-judges protocol, recently advocated by Mclver and Morgan as an example of stepwise refinement of security protocols, studies how to securely compute the majority function to reach a final verdict without revealing each individual judge's decision. We extend their protocol in two different ways for an arbitrary number of 2n+1 judges. The first generalisation is inherently centralised, in the sense that it requires a judge as a leader who collects information from others, computes the majority function, and announces the final result. A different approach can be obtained by slightly modifying the well-known dining cryptographers protocol, however it reveals the number of votes rather than the final verdict. We define a notion of conditional anonymity in order to analyse these two solutions. Both of them have been checked in the model checker MCMAS

Anonymous network access using the digital marketplace

With increasing usage of mobile telephony, and the trend towards additional mobile Internet usage, privacy and anonymity become more and more important. Previously-published anonymous communication schemes aim to obscure their users' network addresses, because real-world identity can be easily be derived from this information. We propose modifications to a novel call-management architecture, the digital marketplace, which will break this link, therefore enabling truly anonymous network access

Questions related to Bitcoin and other Informational Money

A collection of questions about Bitcoin and its hypothetical relatives Bitguilder and Bitpenny is formulated. These questions concern technical issues about protocols, security issues, issues about the formalizations of informational monies in various contexts, and issues about forms of use and misuse. Some questions are formulated in the more general setting of informational monies and near-monies. We also formulate questions about legal, psychological, and ethical aspects of informational money. Finally we formulate a number of questions concerning the economical merits of and outlooks for Bitcoin.Comment: 31 pages. In v2 the section on patterns for use and misuse has been improved and expanded with so-called contaminations. Other small improvements were made and 13 additional references have been include

Verification of Information Flow Properties under Rational Observation

Information flow properties express the capability for an agent to infer information about secret behaviours of a partially observable system. In a language-theoretic setting, where the system behaviour is described by a language, we define the class of rational information flow properties (RIFP), where observers are modeled by finite transducers, acting on languages in a given family $\mathcal{L}$. This leads to a general decidability criterion for the verification problem of RIFPs on $\mathcal{L}$, implying PSPACE-completeness for this problem on regular languages. We show that most trace-based information flow properties studied up to now are RIFPs, including those related to selective declassification and conditional anonymity. As a consequence, we retrieve several existing decidability results that were obtained by ad-hoc proofs.Comment: 19 pages, 7 figures, version extended from AVOCS'201