11,645 research outputs found

    MobChain:Three-Way Collusion Resistance in Witness-Oriented Location Proof Systems Using Distributed Consensus

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    Smart devices have accentuated the importance of geolocation information. Geolocation identification using smart devices has paved the path for incentive-based location-based services (LBS). However, a user’s full control over a smart device can allow tampering of the location proof. Witness-oriented location proof systems (LPS) have emerged to resist the generation of false proofs and mitigate collusion attacks. However, witness-oriented LPS are still susceptible to three-way collusion attacks (involving the user, location authority, and the witness). To overcome the threat of three-way collusion in existing schemes, we introduce a decentralized consensus protocol called MobChain in this paper. In this scheme the selection of a witness and location authority is achieved through a distributed consensus of nodes in an underlying P2P network that establishes a private blockchain. The persistent provenance data over the blockchain provides strong security guarantees; as a result, the forging and manipulation of location becomes impractical. MobChain provides secure location provenance architecture, relying on decentralized decision making for the selection of participants of the protocol thereby addressing the three-way collusion problem. Our prototype implementation and comparison with the state-of-the-art solutions show that MobChain is computationally efficient and highly available while improving the security of LPS

    Postwar Sierra Leone : are programs of reconstruction addressing the causes of war?

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    This multilayered study is an appraisal of some of the ongoing post-conflict reconstruction efforts in Sierra Leone in light of the causes of the conflict, which lasted from 1991-2002. It begins by providing a critical examination of the historical antecedents leading up to the war. The problems of colonialism which brought together different nationalities under one political umbrella by force of arm, along with other motley of issues such as corrupt leadership and inter-ethnic violence led to the outbreak of war in 1991. Although different studies have discussed these factors, very few, if any, have tried to make a connection between causation and reconstruction with a view to find a lasting peace. The aim of the study, therefore, is to appraise the ongoing post-conflict reconstruction efforts in Sierra Leone in light of the causes of the conflict. No lasting peace will be achieved unless there are practical steps addressing the very structures that brought about the war. A central focus is to gain some insights on the successes and failures of the ongoing reconstruction programs. The findings of the study conclude that the post-conflict reconstruction efforts in Sierra Leone have been moderately successful at best. If basic needs such as educational and health care reform, as well as employment opportunities for youth are not met, Sierra Leone will continue to carry a cloud where conditions are still ripe for conflict

    Systemic Corruption in an Advanced Welfare State: Lessons from the Québec Charbonneau Inquiry

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    The Quiet Revolution in the 1960s propelled the province of Québec onto the path of greater social justice and better government. But as the evidence exposed at the Charbonneau inquiry makes clear, this did not make systemic corruption disappear from the construction sector. Rather, it adapted to its new institutional environment and was significantly shaped by the incentives structure it provided. The patterns of corruption emerging from the Charbonneau inquiry bear the imprint of the so-called “Québec model” inherited from the Quiet Revolution in at least three ways: (i) in the economic nationalism that made public policies partial towards French-speaking and Québec-based businesses, notably in the engineering sector, with major firms like SNC-Lavalin using their dominant position as “national champions” to engage in cartel-like practices to raise the price of construction projects; (ii) in the Jacobinism that strongly centralized power at the provincial level and left municipalities underdeveloped in terms of bureaucratic capacity, thus making them easy prey for corrupted interests, and (iii) in the sovereignist/federalist cleavage that, since the 1970s, has made Québec businesses dependent on the Liberal Party for political stability and has allowed party operators to extract a rent from businesses in return

    Trust-based social mechanism to counter deceptive behaviour

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    The actions of an autonomous agent are driven by its individual goals and its knowledge and beliefs about its environment. As agents can be assumed to be selfinterested, they strive to achieve their own interests and therefore their behaviour can sometimes be difficult to predict. However, some behaviour trends can be observed and used to predict the future behaviour of agents, based on their past behaviour. This is useful for agents to minimise the uncertainty of interactions and ensure more successful transactions. Furthermore, uncertainty can originate from malicious behaviour, in the form of collusion, for example. Agents need to be able to cope with this to maximise their benefits and reduce poor interactions with collusive agents. This thesis provides a mechanism to support countering deceptive behaviour by enabling agents to model their agent environment, as well as their trust in the agents they interact with, while using the data they already gather during routine agent interactions. As agents interact with one another to achieve the goals they cannot achieve alone, they gather information for modelling the trust and reputation of interaction partners. The main aim of our trust and reputation model is to enable agents to select the most trustworthy partners to ensure successful transactions, while gathering a rich set of interaction and recommendation information. This rich set of information can be used for modelling the agents' social networks. Decentralised systems allow agents to control and manage their own actions, but this suffers from limiting the agents' view to only local interactions. However, the representation of the social networks helps extend an agent's view and thus extract valuable information from its environment. This thesis presents how agents can build such a model of their agent networks and use it to extract information for analysis on the issue of collusion detection.EThOS - Electronic Theses Online ServiceUniversity of Warwick. Dept. of Computer ScienceGBUnited Kingdo
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