On Secure Workflow Decentralisation on the Internet

Decentralised workflow management systems are a new research area, where most work to-date has focused on the system's overall architecture. As little attention has been given to the security aspects in such systems, we follow a security driven approach, and consider, from the perspective of available security building blocks, how security can be implemented and what new opportunities are presented when empowering the decentralised environment with modern distributed security protocols. Our research is motivated by a more general question of how to combine the positive enablers that email exchange enjoys, with the general benefits of workflow systems, and more specifically with the benefits that can be introduced in a decentralised environment. This aims to equip email users with a set of tools to manage the semantics of a message exchange, contents, participants and their roles in the exchange in an environment that provides inherent assurances of security and privacy. This work is based on a survey of contemporary distributed security protocols, and considers how these protocols could be used in implementing a distributed workflow management system with decentralised control . We review a set of these protocols, focusing on the required message sequences in reviewing the protocols, and discuss how these security protocols provide the foundations for implementing core control-flow, data, and resource patterns in a distributed workflow environment

Securing Peer-to-Peer Overlay Networks

Overlay networks are virtual networks, which exist on top of the current Inter net architecture, and are used in support of peer-to-peer (P2P) applications. The virtualization provides overlays with the ability to create large, scalable, decentral ized networks with efficient routing. Many implementations of overlay networks have come out of academic research. Each provides a unique structure and routing configuration, aimed at increasing the overall network efficiency for a particular ap plication. However, they are all threatened by a similar set of severe vulnerabilities. I explore some of these security deficiencies of overlay network designs and pro pose a new overlay network security framework Phyllo. This framework aims to mitigate all of the targeted security problems across a majority of the current overlay implementations, while only requiring minimal design changes. In order to demonstrate the validity of Phyllo, it was implemented on top of the Pastry overlay architecture. The performance and security metrics of the network with the pro posed framework are evaluated against those of the original in order to demonstrate the feasibility of Phyllo

Security in DHT-based peer-to-peer networks

Questa tesi riguarda il problema dell’integrazione dei meccanismi per la gestione di reputazione e dei processi di lookup nelle reti peer-to-peer basate su DHT (Distributed Hash Table) e l’applicazione di tali tecniche a scenari di reti chiuse e gerarchiche con particolare riferimento al livello di sicurezza e efficienza dello storage e del backup delle risorse. La soluzione proposta rappresenta una combinazione delle tecniche per la valutazione di reputazione e degli strumenti per i sistemi di computer distribuiti come protezione dagli specifici attacchi causati dai peer maliziosi in sistemi P2P collaborativi. Inoltre, e’ stata proposta l’applicazione dei meccanismi DHT nell’ambito delle reti di computer gerarchiche, in particolare nelle reti aziendali. L’obiettivo di questo lavoro e’ quello di offrire una soluzione ai problemi derivanti dall’utilizzo di una architettura centralizzata tramite l’introduzione del sistema di organizzazione dei dati inerente all’ambito P2P basato sugli algoritmi DHT in una rete aziendale.This thesis addresses the problem of integration of reputation management mechanisms and other instruments used in distributed computing environment with lookup processes in DHT-based peer-to-peer networks in order to improve resilience of such systems to destructive actions of malevolent or faulty components. The goal of this integration is to obtain a more efficient, less expensive (in terms of data transferred, computational resources involved and time spent) and possibly simple solution to cope with the specific problems of DHT-based environment. A particular accent has been given to DHT-based environments with a collaborative nature. Another issue considered in this work regards the application of DHT mechanisms to lookup and data retrieval processes in hierarchical collaborative environments, in particular, in enterprise networks. This approach exploits advantages of the P2P data organization system based on DHTs to avoid some problems inherent in systems with centralized architectures

Decentralized trust in the inter-domain routing infrastructure

Inter-domain routing security is of critical importance to the Internet since it prevents unwanted traffic redirections. The current system is based on a Public Key Infrastructure (PKI), a centralized repository of digital certificates. However, the inherent centralization of such design creates tensions between its participants and hinders its deployment. In addition, some technical drawbacks of PKIs delay widespread adoption. In this paper we present IPchain, a blockchain to store the allocations and delegations of IP addresses. IPchain leverages blockchains' properties to decentralize trust among its participants, with the final goal of providing flexible trust models that adapt better to the ever-changing geopolitical landscape. Moreover, we argue that Proof of Stake is a suitable consensus algorithm for IPchain due to the unique incentive structure of this use-case, and that blockchains offer relevant technical advantages when compared to existing systems, such as simplified management. In order to show its feasibility and suitability, we have implemented and evaluated IPchain's performance and scalability storing around 350k IP prefixes in a 2.5 GB chain.Peer ReviewedPostprint (published version

Towards Securing Peer-to-peer SIP in the MANET Context: Existing Work and Perspectives

The Session Initiation Protocol (SIP) is a key building block of many social applications, including VoIP communication and instant messaging. In its original architecture, SIP heavily relies on servers such as proxies and registrars. Mobile Ad hoc NETworks (MANETs) are networks comprised of mobile devices that communicate over wireless links, such as tactical radio networks or vehicular networks. In such networks, no fixed infrastructure exists and server-based solutions need to be redesigned to work in a peer-to-peer fashion. We survey existing proposals for the implementation of SIP over such MANETs and analyze their security issues. We then discuss potential solutions and their suitability in the MANET context

Overview of Polkadot and its Design Considerations

In this paper we describe the design components of the heterogenous multi-chain protocol Polkadot and explain how these components help Polkadot address some of the existing shortcomings of blockchain technologies. At present, a vast number of blockchain projects have been introduced and employed with various features that are not necessarily designed to work with each other. This makes it difficult for users to utilise a large number of applications on different blockchain projects. Moreover, with the increase in number of projects the security that each one is providing individually becomes weaker. Polkadot aims to provide a scalable and interoperable framework for multiple chains with pooled security that is achieved by the collection of components described in this paper

Towards a worldwide storage infrastructure

Peer-to-peer systems have recently gained a lot of attention in the academic community especially through the design of KBR (Key-Based Routing) algorithms and DHT (Distributed Hash Table)s. On top of these constructs were built promising applications such as video streaming applications but also storage infrastructures benefiting from the availability and resilience of such scalable network protocols. Unfortunately, rare are the storage systems designed to be scalable and fault-tolerant to Byzantine behaviour, conditions required for such systems to be deployed in an environment such as the Internet. Furthermore, although some means of access control are often provided, such file systems fail to offer the end-users the flexibility required in order to easily manage the permissions granted to potentially hundreds or thousands of end-users. In addition, as for centralised file systems which rely on a special user, referred to as root on Unices, distributed file systems equally require some tasks to operate at the system level. The decentralised nature of these systems renders impossible the use of a single authoritative entity for performing such tasks since implicitly granting her superprivileges, unacceptable configuration for such decentralised systems. This thesis addresses both issues by providing the file system objects a completely decentralised access control and administration scheme enabling users to express access control rules in a flexible way but also to request administrative tasks without the need for a superuser. A prototype has been developed and evaluated, proving feasible the deployment of such a decentralised file system in large-scale and untrustworthy environments

Fit-Broker: delivering a reliable service for event dissemination

Tese de mestrado em Segurança da Informação, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2013Os serviços de nuvem (Cloud) estão a assumir um papel cada vez mais importante no mundo de fornecimento de serviços. Estes serviços variam desde a oferta de simples ferramentas de trabalho até a disponibilização de infraestruturas remotas de computação. Como tal, a correcta monitorização das infraestruturas de nuvem assume um papel vital de forma a garantir disponibilidade e o cumprimento de acordos de nível de serviço. Existem alguns estudos recentes que mostram que este tipo de infraestruturas não se encontra preparada para enfrentar atuais e futuros problemas de segurança que podem ocorrer. Parte deste problema advém do facto de as ferramentas de monitorização serem centralizadas e de apenas suportarem alguns tipos de falhas. De forma a tornar os sistemas de monitorização mais resilientes, esta dissertação propõe uma solução para aumentar a confiabilidade no transporte de informação entre os seus vários pontos. Trata-se de uma framework adaptável e resiliente de disseminação de eventos baseada no paradigma de publicador-subscritor. Esta oferece múltiplos níveis de resiliência e qualidades de serviço que podem ser combinados para oferecer uma qualidade de serviço e de proteção adequada às necessidades de cada sistema. Este documento descreve a arquitectura da framework bem como todo seu funcionamento interno e interfaces oferecidas. Este documento descreve ainda um conjunto de testes realizados de forma a avaliar a performance da framework em vários cenários distintos.Cloud services are assuming a greater role in the world of service providing. These services can range from the simple working tool to a complete remote computing infrastructure. As such, the correct monitoring of this type of infrastructures represents a key requirement to ensure availability and the fulfilment of the service level agreements. Recent studies show that these infrastructures are not prepared to face some current and future security issues. Part of these problems resides in the fact that current monitoring tools are centralized and are only prepared to deal with some types of faults. In order to increase the resilience of monitoring systems, this dissertation proposes a framework capable of increasing the reliability of the transport of information between their many peers. It is a adaptable and resilient framework for event dissemination based on the publisher-subscriber paradigm. The framework offers multiple levels of resilience and quality of services that can be combined to meet the necessities of quality of service and protection of each system. This document describes the architecture, internal mechanism and interfaces of the framework. Also, we describe a series of tests that where used to evaluate the performance of the framework in different scenarios