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Unstructured P2P systems exhibit a great deal of robustness and self-healing at the cost of reduced scalability. Resource location is performed using a broadcast-like process called flooding. The work presented in this paper comprises an effort to reduce the overwhelming volume of traffic generated by flooding, thus increasing the scalability of unstructured P2P systems. Using a simple hash-based content categorization method the Ultrapeer overlay network is partitioned into a relatively small number of distinct subnetworks. By employing a novel index splitting technique each leaf peer is effectively connected to each different subnetwork. The search space of each individual flooding is restricted to a single partition, and is thus considerably limited. This reduces significantly the volume of traffic produced by flooding without affecting at all the accuracy of the search method. Experimental results demonstrate the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Copyright of Achievements in European Research on Grid Systems is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Interactive Problem Solving Environments (PSEs) offer an integrated approach for constructing and running complex systems, such as distributed simulation systems. To achieve efficient execution of High Level Architecture (HLA)-based distributed interactive simulations on the Grid, we introduce a PSE called Grid HLA Management System (G-HLAM) for their management. This is done by introducing migration and monitoring mechanisms for such applications. In this paper we present how G-HLAM can be applied to the applications supporting surgeons with simulations of vascular reconstruction, using distributed federations on the Grid for the communication among simulation and visualization components. [ABSTRACT FROM AUTHOR]

Enabling high-level programming models on grids is today a major challenge. A way to achieve this goal relies on the use of environments able to transparently and automatically provide adequate support for low-level, grid-specific issues (fault-tolerance, scalability, etc.). This paper discusses the above approach when applied to grid data management. As a case study, we propose a 2-tier software architecture that supports transparent, fault-tolerant, grid-level data sharing in the ASSIST programming environment (University of Pisa), based on the JuxMem grid data sharing service (INRIA Rennes). [ABSTRACT FROM AUTHOR]

Currently, Grid applications are usually developed for a network offering only a best effort packet delivery service. Nevertheless, High Performance Computing applications with Quality of Service requirements stress the capabilities of the interconnecting network of the target Grid infrastructure. Therefore, the application runtime environment must interact, through a Grid Resource Broker, with a Network Resource Manager to obtain information about the network and to reserve network resources among the computational resources that will host the execution of the applications. The paper presents the design and the development of a Grid Network-Aware Resource Broker. It enhances the features of a Grid Resource Broker with the capabilities provided by a Network Resource Manager. The innovative contribution of the presented integration is the possibility to design and implement new mapping/scheduling mechanisms to take into account both network and computational resources. Finally, we will show how to exploit the new features offered by the Grid Network-Aware Resource Broker in scheduling parallel applications with QoS requirements. [ABSTRACT FROM AUTHOR]

Building and evolving grid applications is complex. A promising approach to managing this complexity is component-based development, currently attracting growing interest in the grid community. Evaluating the effectiveness of component-based development requires real-world experience. To this end, this paper presents a case study in reengineering a high performance numerical solver to become a component-based grid application. The adopted component model is an extension of the generic Fractal model that specifically targets grid environments. The paper provides qualitative and quantitative evidence that componentisation has improved the modifiability and reusability of the application without significantly affecting performance. [ABSTRACT FROM AUTHOR]

As Grids enlarge their boundaries and users, some of their functions should be decentralized to avoid bottlenecks and guarantee scalability. A way to provide Grid scalability is to adopt Peer-to-Peer (P2P) models to implement non hierarchical decentralized Grid services and systems. A core Grid functionality that can be effectively redesigned using the P2P approach is resource discovery. This paper proposes a P2P resource discovery architecture aiming to manage various Grid resources and complex queries. Its goal is two-fold: to address discovery of multiple resources, and to support discovery of dynamic resources and arbitrary queries in Grids. The architecture includes a scalable technique for locating dynamic resources in large-scale Grids. Simulation results are provided to demonstrate the efficiency of the proposed technique. [ABSTRACT FROM AUTHOR]

One way to ease the development of Grid applications is to specify and design an Integrated Toolkit which will enable the development of Grid-unaware applications i.e. applications where the Grid is transparent to them but that are able to exploit its resources. Achieving this vision of an Integrated Toolkit requires the investigation and definition of integration between different systems. This paper studies the integration possibilities of GriCoL, a language for the description of complex Grid experiments, and GRID superscalar, a run-time environment which automatically converts sequential program code and deploys it for execution on a Grid. GriCoL operates on a multi-layer paradigm, using both a control flow layer and a data flow layer. We propose integration with GRID superscalar at each of these layers, concluded that integration at the control flow level is difficult to achieve but at the data flow level is possible. [ABSTRACT FROM AUTHOR]

The emerging Grid applications require rigorous approaches to handle security management issues as their scale, heterogeneity, and complexity can not be handled with simple examination and monitoring mechanisms. In this paper, we propose a rigorous method of deriving security policies for grid applications. These policies are derived from a security requirements model built using the KAOS requirements engineering methodology. We consider an example grid application of distributed file system; its formal security requirements model is developed followed by its refinement and then the derivation of security policy for this application. The derived policies are refined and transformed into operational policies for their implementation. We developed templates for the security policies to facilitate and formalise the various stages of policy derivation. [ABSTRACT FROM AUTHOR]

Interactive problem solving environments are gaining widespread acceptance within the Grid community. While developing applications and frameworks to support and to integrate with these interactive environments is very important, it is also necessary to treat the legacy applications with the same importance. In this paper, we report an ongoing effort in enabling a legacy application to support, integrate with, and evolve as a scalable problem solving environment for Earth system modelling. Our strategy has been to componentise the existing legacy framework, augment each component with metadata, and using this metadata address different issues arising when performing component composition. We describe the means for specifying, publishing, and using the metadata in solving two different but crucially important issues when performing component composition - model validation and model efficiency. [ABSTRACT FROM AUTHOR]

In this paper the use of a Grid-enabled system for performance monitoring of GRID superscalar-compliant applications is addressed. Performance monitoring is built on top of the OCM-G monitoring system developed in the EU IST CrossGrid project. A graphical user tool G-PM is used to interpret information received from the monitoring system. We discuss the issues related to the performance analysis of GRID superscalar applications and present the current work progress with focus on the refinement of existing implementation issues and present the required changes to the G-PM and OCM-G architecture. At the end a case study of performance monitoring is presented. [ABSTRACT FROM AUTHOR]

In SOA-based Grid environments service provider and service consumer usually do not know each other. In order to establish a business relation they must inter alia (i) create a trust relationship, and (ii) set up mechanisms to create reliable, verifiable, and, at least in a commercial environment, also audible agreements with respect to the services requested, delivered and consumed. In this paper we will only briefly address (i) but concentrate on solutions for (ii) based on Service Level Agreements (SLAs). Therefore we will give an overview on the state-of-the-art of SLA usage in Grids, highlight possible obstacles for the deployment of SLAs, and present a detailed example of a service improving the execution of workflows through the use of WS-Agreement to negotiate advance reservation of resources to execute workflow components. [ABSTRACT FROM AUTHOR]

Copyright of Achievements in European Research on Grid Systems is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 2006 MACE workshop [1, 28] has presented the drivers and challenges of Autonomic Networking [2] and fostered an understanding of emerging principles for this new type of networks [3]. In this paper, we present concepts and principles that define a technological neutral, architectural perspective of Autonomic Networks. The work presented in largely based on work within the Architecture team of the TeleManagement Forum (Technological Neutral Architecture, [4]) and joined research work of industrial and academic research teams (for example Ericsson [5], HP & QinetiQ [6] and Motorola [7]). The goal of this paper is to provide the reader with manageability guidelines and architectural patterns leading to the development of manageable autonomic software and communication systems. We present a component-based, distributed system architecture and an associated set of critical system services that Autonomic Networks require. Since we tackle the problem from a technologically neutral angle, this paper will not prescribe a single new technology, but rather provide a means that allows for federating different technologies, each of which offers particular advantages at business and system levels. In particular, it enables business concepts and principles to drive system design and architectures. This may be further implemented using currently available distributed systems information technologies. [ABSTRACT FROM AUTHOR]

"The next thing in technology is not just big but truly huge: the conquest of complexity", Andreas Kluth, The Economist [7]. The future of the Information Society draws a world where devices with processing capabilities are ubiquously connected to information sources. Due to the diversity of user devices, technologies, communication accesses, etc. operators do really need a technology able to manage such a complex environment giving a service end to end vision. In this sense, the set of technologies that arise from Autonomic Communication appears to be the cornerstone in order to manage the complexity of these new networks and services infrastructure. Competitive market is hard and telecommunication operators must face a double challenge, on one hand they must offer powerful services that must be managed, on the other hand they must address the reduction of service margins. Only really efficient operators will survive in such an environment. The I2OSS (Intelligence to Operational Support Systems) model is thought to provide operators with management infrastructures showing the advantages of Autonomic Communications. The reader will find in this article a technological framework for innovation in the field of Autonomic Communications. The I2OSS model establishes a methodological approach for innovation on OSS (Operation Support Systems) systems that support the management processes of a telco operator. No concrete or specific solutions will be found, but indications on how a telco operator must drive innovation to take advantage of "Autonomic Technologies". [ABSTRACT FROM AUTHOR]

Current network management systems have been impeded by a scarcity of open standards for interoperable management solutions. Information models have made progress in promoting interoperability of traditional "centralised" networks but have still to significantly address the proliferation of next generation networks such as autonomic networks. Such networks impose challenges which include distributed self-control and self-management. The goal of the Madeira project was to utilise novel technologies and methodologies, based on an underlying P2P paradigm, for a logically meshed, distributed Network Management System (NMS) that facilitates dynamic behaviour of transient network elements. In this paper, we describe a solution for a meta-model that attempts to capture the key concepts behind the task of network management of a mesh network. A case-study focusing on the fault management of such a network will be presented with the purpose of verifying the applicability of such a meta-model. [ABSTRACT FROM AUTHOR]

This paper presents an approach to manipulating available hybrid connectivity to autonomically maximise the potential for sustained connectivity in the event of path disruptions. The approach is documented in terms of the features, architecture and deployment modes of an autonomic communications module, termed RASCAL. This module employs software-agent logic supported by a state-of-the-art policy engine to dynamically determine best options for packet transmission over available infrastructure and ad-hoc connections. [ABSTRACT FROM AUTHOR]

During the last decade, networks have been growing dramatically on several dimensions: the number of users has been multiplied by more than 15, the amount of traffic by more than 100 and the number of network technologies and usages has also been diversified. One of the main consequences of this growth is the increase in dynamicity of the network behaviour. Therefore, it is more and more difficult for human operators to manage the network in an efficient way. That is why current research in the field of network management tends to automate network control and management. A large initiative has been proposed by IBM to give more autonomy to computing systems: Autonomic Computing Initiative. The paradigm of Autonomic Networking was introduced as an extension of Autonomic Computing, focusing on the autonomy of networks. At the centre of it lies knowledge management. In fact, to be self-managed, a network element needs to know a lot about its environment. But sharing a large amount of knowledge over a large network is very expensive in terms of resources. Therefore, new knowledge management mechanisms are required. A good example of networks that need to be autonomic is military networks. In fact, on one hand, military communication environment is very dynamic, and very uncertain; and on the other hand, quick decisions have to be triggered to guarantee -whenever it is possible- the connectivity for strategical communications. This paper proposes an interpretation of the Autonomic Networking paradigm, a description of a situatedness-based knowledge plane, and an instantiation of these concepts to a concrete application: resource regulation in IP military networks. [ABSTRACT FROM AUTHOR]

This chapter presents the Living Systems Autonomic Service Access Management Suite, LS/ASAM, a comprehensive middleware solution enabling adaptive connectivity management of nomadic end hosts across heterogeneous access networks with autonomic optimisation of network performance and availability. [ABSTRACT FROM AUTHOR]

Autonomic communication aims to build more reflective systems with properties like self-healing, self-organisation, self-optimisation and so forth — the so-called "self-*" properties. To attain this within the existing strictly-layered approaches to network software may be possible to certain extent, but will not leverage all the possible optimisations, and we suggest that cross-layer architectures are better-suited to achieving the self-* properties. This paper explores the possibilities of cross-layering approaches in autonomic networks, reviews and compares the different cross-layer approaches to network architecture, observing that most current approaches depend purely on local information and provide only poor and inaccurate information gathering at the network level. [ABSTRACT FROM AUTHOR]

MPLS DiffServ-TE combines the advantages of DiffServ and MPLSTE by allowing a differentiation of services and a traffic engineering based on a fast packet switching technology. However, such MPLS DiffServ-TE network needs an efficient method for Quality of Service (QoS) guaranteeing. In addition, the management of such a network is not a simple function and could not be done manually. In fact, it would be much more economic and effective to let equipments handle a part of the tasks attributed currently to the human administrator. In this paper, a novel architecture based on a Multi-Agent System is proposed to automatically manage MPLS DiffServ-TE domains. To meet the QoS requirements, an LSP creation strategy, based on a traffic-driven approach and depending on the traffic load, is proposed. It determines when to set up a new LSP and when to forward a new traffic in an already existing one. This strategy reduces the number of LSPs and the number of signalling operations in the network. Simulation results are provided to illustrate the efficiency of our proposition. [ABSTRACT FROM AUTHOR]

In order to enable the autonomic network resource management, we resort to game theory to facilitate the spectrum sharing between heterogeneous wireless networks. We set the spectrum sharing objective to improve spectrum efficiency and maximise network revenue. Based on this goal, we propose a revenue sharing bargain game to model the spectrum sharing behaviour of intra-operator radio access networks (RANs) and a price bargain game to model the spectrum trading behaviour between inter-operator RANs. Furthermore, we adopt multi-agent architecture to implement the spectrum sharing schemes autonomously. Both bargaining mechanisms are analysed using bargaining game theory, and consequently the implementations are refined and simplified based on the analysis. Simulation results show that the proposed mechanisms outperform the conventional fixed spectrum management method in network revenue, spectrum efficiency and call blocking rate. [ABSTRACT FROM AUTHOR]

An enormous amount of multimedia data will be transmitted by various devices in the wireless personal area network, and this network environment will require very high transmission capacity. In this paper, we apply multiple antennas to MB-OFDM UWB system for high performance. With an emphasis on a preamble design for multichannel separation, we address the channel estimation in MB-OFDM system with multiple antennas. By properly designing each preamble for multiple antennas to be orthogonal in the time domain, the channel estimation can be applied to the MB-OFDM proposal for IEEE 802.15.3a standard in the case of more than two transmit antennas. By using the multiantenna scheme and proposed channel estimation technique, the reliability and performance of the MB-OFDM system can be improved. [ABSTRACT FROM AUTHOR]

A combination of OFDM with FDMA (called OFDMA) is regarded as a promising solution for improving the performance of BWA with multiple users. Although transmit diversity is clearly advantageous in OFDMA systems, it may not be possible that practical OFDMA systems have more than two antennas due to size, cost, or hardware limitations. Cooperative networks aim to utilize the available terminals as a collection of distributed antennas for the transmission of signals from one end of the network to the other. This paper focuses on design and performance evaluation of IEEE 802.16 MIMO-OFDMA systems with cooperative diversity. In this chapter, for high-rate and reliable transmission, efficient transmission codes of cooperative transmission are proposed for each transmission case (single transmission case or mutual transmission case). [ABSTRACT FROM AUTHOR]

Radio frequency identification (RFID) technology is not fundamentally new and concerns a whole range of applications. The first RFID application may have been the Royal British Air Force's "Identify Friend or Foe" system, which was used during the Second World War to identify friendly aircraft. RFID can be applied to a variety of tasks, structures, work systems, and contexts along the value chain, including business-to-business (B-2-B) logistics, internal operations, business-toconsumer (B-2-C) marketing, and after-sales service applications [1-6]. However, the boom that RFID technology enjoys today is basically due to the standardization [7] and development of low cost devices. Like every wireless device, RFID systems bring with them security and privacy issues to all those people who have been working in this area. Security issues involve classic attacks, namely denial of service, impersonation of tags, or channel eavesdropping. These attacks are rendered more practicable because of the tags' lack of computational and storage capacity. There are many papers investigating these issues in various ways [7, 8, 10-12, 14]. Today's challenge is to find protocols (or deployments) which allow authorized parties to identify the tags without an adversary being able to track them, thus getting to the root of the privacy problem [8, 13]. It is well known that the reason not to use well known authentication protocols is that such protocols do not preserve the privacy of the provider. Asymmetric cryptography could easily solve this problem, but it is too heavy to be implemented within a tag. [ABSTRACT FROM AUTHOR]

Searching information on the Web can be viewed as extremely easy, or it can be extremely difficult. This is because the WWW is not indexed like many library catalogs or journal-article indexes. When we search on the Web, we are not searching it directly but are actually searching the Web pages collected and indexed by a search tool from computers all over the world that contains the actual Web pages. Examples of search tools are Yahoo! Search, Google, Alta Vista, and so on. The different types of search tools have their own strengths and weaknesses. Depending on your information needs, one may work better for you than another. Search directories are hierarchical databases with references to websites. The websites that are included are classified according to the rules of that particular search service. Search engines, on the other hand, use software to crawl the Internet in search of what you would like using of terms or keywords. Specialized databases are the hidden parts of the WWW that are normally not found by regular search engines [1]. This paper presents the extension work from Integrated Filtered Web-Search Engine (IFWSE) [2] by looking at the enhancement of the program structure to retrieve the search hits. Further experiments were also carried out to compare its performance with with a well-established, meta-search engine-the MetaCrawler [3] [4]. [ABSTRACT FROM AUTHOR]

Tamper-resistant software which implements a block cipher with a fixed embedded cryptographic key is important for securing embedded systems for digital rights management, access control, and other applications. The security of such software is measured by its ability to hide the embedded key against numerous known attacks. A class of methods for constructing tamper-resistant software by using a number of look-up tables is called a white-box implementation or table-network implementation. We developed a method of evaluating the security of table-network implementations of the Data Encryption Standard (DES). Link and Neumann proposed a table-network implementation of DES that is claimed to be resistant against all known attacks, which are effective for table-network implementations of DES proposed by Chow, Eisen, Johnson, and van Oorschot. In this paper, we point out the existence of a new attack, which allows efficient extraction of the hidden key in the Link-Newman table-network implementation of DES. Our result should contribute in completing the list of attacking methodologies and thus help the design of better tamper-resistant software. [ABSTRACT FROM AUTHOR]

In the recent years, several practical methods have been published to compute collisions on some commonly used hash functions. Starting from two messages m1 and m2 these methods permit to compute m1′ and m2′ similar to the former such that they have the same image for a given hash function. In this paper we present a method to take into account, at the symbolic level, that an intruder actively attacking a protocol execution may use these collision algorithms in reasonable time during the attack. This decision procedure relies on the reduction of constraint solving for an intruder exploiting the collision properties of hash functions to constraint solving for an intruder operating on words, that is with an associative symbol of concatenation. The decidability of the latter is interesting in its own right as it is the first decidability result that we are aware of for an intruder system for which unification is infinitary, and permits to consider in other contexts an associative concatenation of messages instead of their pairing. [ABSTRACT FROM AUTHOR]

Web Services have become more and more important in these years, and BPEL4WS is a de facto standard for the web service composition and orchestration. We have proposed a language BPEL0 to capture the important features of BPEL4WS, with the scope-based compensation and fault handling mechanism. In this paper we formalize the denotational semantics for BPEL0, which can support the refinement calculus and the verification of program equivalence. A set of algebraic laws is investigated within the denotational framework. The distinct features of BPEL0 make the investigation of the denotational semantics and algebraic laws more challenging. [ABSTRACT FROM AUTHOR]

In their seminal paper on certificateless public key cryptography, Al-Riyami and Paterson (AP) proposed a certificateless authenticated key agreement protocol. Key agreement protocols are one of the fundamental primitives of cryptography, and allow users to establish session keys securely in the presence of an active adversary. AP's protocol essentially requires each party to compute four bilinear pairings. Such operations can be computationally expensive, and should therefore be used moderately in key agreement. In this paper, we propose a new certificateless authenticated two-party key agreement protocol that only requires each party to compute two pairings. We analyze the security of the protocol and show that it achieves the desired security attributes. Furthermore, we show that our protocol can be used to establish keys between users of different key generation centers. [ABSTRACT FROM AUTHOR]

Digital Rights Management frameworks (DRM) aim at protecting and controlling information contents widely distributed on client devices. Using a license, the content provider can decide which rights can be rendered and who are the authorized end-users (as identity holders) allowed to exercise those rights. Most of the time, it is hard to add new feature to the client application, it is even impossible when the new feature is not considered trustworthy by the corporation distributing the rendering application. In a same way, the rendering application identifies the end-user with a dedicated identity and it is impossible to take into account an identity provided by an external corporation. In this paper, we aim at providing a federated approach called FORM where a content provider can decide to trust external rendering rights and external identities. We even go further introducing identity providers, actions providers as we consider content providers. Thus, all kind of providers can define license specifying what can be done with the object they provide. FORM defines a new license model and a new license interpretation mechanism taking into account all licenses issued by a federation of object providers. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel method of safety analysis for runtime code update, i.e., updating a program at runtime without terminating its execution. Runtime code update is an emerging technique especially for increasing availability of the servers which should always be in service and free of any known bugs or security flaws. However, it may cause state inconsistency or unintended behaviors unless it is properly restricted. Although too much restriction enables us to easily ensure safety of updating code at runtime, it prevents us from coping with the realistic updates. To reveal appropriate restriction, we first construct a very precise model of safe runtime code update based on a framework of explicit data/control flow and dependency. Then, a class of analyses which statically estimates the set of safe update points is derived by approximating the model. We restrict only the timing: behaviorally safe runtime code update may occur only at safe update points. Moreover, we can relax the restriction by explicitly specifying non-critical points. [ABSTRACT FROM AUTHOR]

Non-interference is typically used as a baseline security policy to formalize confidentiality of secret information manipulated by a program. In contrast to static checking of non-interference, this paper considers dynamic, automaton-based, monitoring of information flow for a single execution of a sequential program. The monitoring mechanism is based on a combination of dynamic and static analyses. During program execution, abstractions of program events are sent to the automaton, which uses the abstractions to track information flows and to control the execution by forbidding or editing dangerous actions. The mechanism proposed is proved to be sound, to preserve executions of well-typed programs (in the security type system of Volpano, Smith and Irvine), and to preserve some safe executions of ill-typed programs. [ABSTRACT FROM AUTHOR]

Control-hijacking attacks are known as critical threats to software security. Control flow monitoring is a kind of important method to mitigate this problem. In this paper, we present a new method for program control flow monitoring. Based on the static analysis of a program, we apply very simple instrumentation of a program's source code to encode its runtime function level control flow traces and check the correctness of the traces in the OS kernel. Experiments show that this method has a tiny performance impact and is still highly effective in detecting control-hijacking attacks. We also propose to automatically handle non-standard control flow by learning programs' dynamic profiling data. Our method is hopeful to be enforceable in different environments because it does not depend closely on specific platform features and the underlying techniques can be easily found in many platforms. [ABSTRACT FROM AUTHOR]

We present modular formalizations of the model specification language Reactive Modules and the temporal logic CTL* in the proof assistant Coq. In our formalizations, both shallow and deep embeddings of each language are given. The modularity of our formalizations allows proofs and theorems to be reused across different embeddings. We illustrate the advantages of our modular formalizations by proving the mutual exclusion property of the Bakery algorithm in different embeddings. [ABSTRACT FROM AUTHOR]

A major difficulty for tracking information flow in multithreaded programs is due to the internal timing covert channel. Information is leaked via this channel when secrets affect the timing behavior of a thread, which, via the scheduler, affects the interleaving of assignments to public variables. This channel is particularly dangerous because, in contrast to external timing, the attacker does not need to observe the actual execution time. This paper presents a compositional transformation that closes the internal timing channel for multithreaded programs (or rejects the program if there are symptoms of other flows). The transformation is based on spawning dedicated threads, whenever computation may affect secrets, and carefully synchronizing them. The target language features semaphores, which have not been previously considered in the context of termination-insensitive security. [ABSTRACT FROM AUTHOR]

In a process calculus, an agent guarantees responsive usage of a channel name r if a communication along r is guaranteed to eventually take place. Responsiveness is important, for instance, to ensure that any request to a service be eventually replied. We propose two distinct type systems, each of which statically guarantees responsive usage of names in well-typed pi-calculus processes. In the first system, we achieve responsiveness by combining techniques for deadlock and livelock avoidance with linearity and receptiveness. The latter is a guarantee that a name is ready to receive as soon as it is created. These conditions imply relevant limitations on the nesting of actions and on multiple use of names in processes. In the second system, we relax these requirements so as to permit certain forms of nested inputs and multiple outputs. [ABSTRACT FROM AUTHOR]

Given an arbitrary intruder deduction capability, modeled as an inference system ${\cal S}$ and a protocol, we show how to compute an inference system $\widehat{\cal S}$ such that the security problem for an unbounded number of sessions is equivalent to the deducibility of some message in $\widehat{\cal S}$. Then, assuming that $\cal S$ has some subformula property, we lift such a property to $\widehat{S}$, thanks to a proof normalisation theorem. In general, for an unbounded number of sessions, this provides with a complete deduction strategy. In case of a bounded number of sessions, our theorem implies that the security problem is co-NP-complete. As an instance of our result we get a decision algorithm for the theory of blind-signatures, which, to our knowledge, was not known before. [ABSTRACT FROM AUTHOR]