2,442 research outputs found

    Safer in the Clouds (Extended Abstract)

    Full text link
    We outline the design of a framework for modelling cloud computing systems.The approach is based on a declarative programming model which takes the form of a lambda-calculus enriched with suitable mechanisms to express and enforce application-level security policies governing usages of resources available in the clouds. We will focus on the server side of cloud systems, by adopting a pro-active approach, where explicit security policies regulate server's behaviour.Comment: In Proceedings ICE 2010, arXiv:1010.530

    Data mining for detecting Bitcoin Ponzi schemes

    Full text link
    Soon after its introduction in 2009, Bitcoin has been adopted by cyber-criminals, which rely on its pseudonymity to implement virtually untraceable scams. One of the typical scams that operate on Bitcoin are the so-called Ponzi schemes. These are fraudulent investments which repay users with the funds invested by new users that join the scheme, and implode when it is no longer possible to find new investments. Despite being illegal in many countries, Ponzi schemes are now proliferating on Bitcoin, and they keep alluring new victims, who are plundered of millions of dollars. We apply data mining techniques to detect Bitcoin addresses related to Ponzi schemes. Our starting point is a dataset of features of real-world Ponzi schemes, that we construct by analysing, on the Bitcoin blockchain, the transactions used to perform the scams. We use this dataset to experiment with various machine learning algorithms, and we assess their effectiveness through standard validation protocols and performance metrics. The best of the classifiers we have experimented can identify most of the Ponzi schemes in the dataset, with a low number of false positives

    Timed Session Types

    Full text link
    Timed session types formalise timed communication protocols between two participants at the endpoints of a session. They feature a decidable compliance relation, which generalises to the timed setting the progress-based compliance between untimed session types. We show a sound and complete technique to decide when a timed session type admits a compliant one. Then, we show how to construct the most precise session type compliant with a given one, according to the subtyping preorder induced by compliance. Decidability of subtyping follows from these results

    A note on two notions of compliance

    Get PDF
    We establish a relation between two models of contracts: binary session types, and a model based on event structures and game-theoretic notions. In particular, we show that compliance in session types corresponds to the existence of certain winning strategies in game-based contracts.Comment: In Proceedings ICE 2014, arXiv:1410.701

    Dissecting Ponzi schemes on Ethereum: identification, analysis, and impact

    Full text link
    Ponzi schemes are financial frauds which lure users under the promise of high profits. Actually, users are repaid only with the investments of new users joining the scheme: consequently, a Ponzi scheme implodes soon after users stop joining it. Originated in the offline world 150 years ago, Ponzi schemes have since then migrated to the digital world, approaching first the Web, and more recently hanging over cryptocurrencies like Bitcoin. Smart contract platforms like Ethereum have provided a new opportunity for scammers, who have now the possibility of creating "trustworthy" frauds that still make users lose money, but at least are guaranteed to execute "correctly". We present a comprehensive survey of Ponzi schemes on Ethereum, analysing their behaviour and their impact from various viewpoints

    Blockchain for social good: a quantitative analysis

    Full text link
    The rise of blockchain technologies has given a boost to social good projects, which are trying to exploit various characteristic features of blockchains: the quick and inexpensive transfer of cryptocurrency, the transparency of transactions, the ability to tokenize any kind of assets, and the increase in trustworthiness due to decentralization. However, the swift pace of innovation in blockchain technologies, and the hype that has surrounded their "disruptive potential", make it difficult to understand whether these technologies are applied correctly, and what one should expect when trying to apply them to social good projects. This paper addresses these issues, by systematically analysing a collection of 120 blockchain-enabled social good projects. Focussing on measurable and objective aspects, we try to answer various relevant questions: which features of blockchains are most commonly used? Do projects have success in fund raising? Are they making appropriate choices on the blockchain architecture? How many projects are released to the public, and how many are eventually abandoned?Comment: In GOODTECHS 201

    Honesty by typing

    Get PDF
    We propose a type system for a calculus of contracting processes. Processes may stipulate contracts, and then either behave honestly, by keeping the promises made, or not. Type safety guarantees that a typeable process is honest - that is, the process abides by the contract it has stipulated in all possible contexts, even those containing dishonest adversaries

    Oraculizando a los ciudadanos : Demagogia y profanación de las inscripciones oraculares en Caballeros de Aristófanes (vv. 818- 819)

    Get PDF
    Dentro de los ataques cómicos que el Morcillero emite a Paflagonio en Caballeros de Aristófanes, uno en particular describe las formas que le permitieron a este figurado Cleón construir su poder sobre Atenas. Luego de que el propio Paflagonio se comparara con el gran Temístocles, el Morcillero expone los modos perniciosos de hacer política: en vv. 818-819, dice que Paflagonio convirtió a Atenas en una ciudad pequeña "levantando muros a través de ella y oraculizando". La primera estrategia remite al dicho del "divide y triunfarás". La segunda, en cambio, hace referencia a una institución político-religiosa como la adivinación. El oráculo, que era un aparato ideológico de la polis ateniense, aparece en el drama como un mensaje legitimador de quien detenta o detentará el poder y Aristófanes echa un manto de sospecha sobre dicha institución sagrada que es manipulada con fines propagandísticos. Con base en estas reflexiones, esta ponencia se propone analizar en Caballeros la denuncia del Morcillero sobre el ocultamiento de los oráculos inscriptos, su vínculo con el contexto socio- histórico de su inscripción y los motivos cómicos que subyacen en la operatoria de profanación de los mensajes divinosWith the comic critics that the Sausage-seller does against Paphlagon in Knights, Aristophanes describes how the demagogue Cleon builds up his power over Athenas. After the comparison with Themistocles, the Sausage-seller explains two injurious ways of doing politics: in vv. 818- 819, he accuses Paplagon of destroyng the greatness of the Athenian's city "by rearing barriers between them and chanting oracles". The first acussation talks about the strategy of fomenting hostility between classes. The second one makes reference to a religious and politic institution like the divination. The oracle, that was a ideological apparatus of the athenian polis, is showed in the comedy as the legitimized message about who holds or will hold the power. Thus Aristophanes blames the manipulation of that sacred institution with propagandistic purposes. This paper aims to analyze the Sausage-seller's accusation against the hidden writing oracle, its socio-historical context of inscription and the comic representation that lies beneath the divine message's profanatio

    Contract agreements via logic

    Full text link
    We relate two contract models: one based on event structures and game theory, and the other one based on logic. In particular, we show that the notions of agreement and winning strategies in the game-theoretic model are related to that of provability in the logical model.Comment: In Proceedings ICE 2013, arXiv:1310.401

    Choreographies in the wild

    Get PDF
    We investigate the use of choreographies in distributed scenarios where, as in the real world, mutually distrusting (and possibly dishonest) participants may be unfaithful to their expected behaviour. In our model, each participant advertises its promised behaviour as a contract. Participants may interact through multiparty sessions, created when their contracts allow to synthesise a choreography. We show that systems of honest participants (which always adhere to their contracts) enjoy progress and session fidelity
    corecore