207 research outputs found
Data mining for detecting Bitcoin Ponzi schemes
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
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
Smart Contracts Contracts
This paper explores the connection between software contracts and smart contracts. Despite the assonance, these two terms denote quite different concepts: software contracts are logical properties of software components, while smart contracts are programs executed on blockchains. What is the relation between them? We answer this question by discussing how to integrate software contracts in the design of programming languages for smart contracts
A note on two notions of compliance
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
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
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
Contract agreements via logic
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
Jalapa: Securing Java with Local Policies Tool Demonstration
AbstractWe present Jalapa, a tool for securing Java bytecode programs with history-based usage policies. Policies are defined by usage automata, that recognize the forbidden execution histories. Usage automata are expressive enough to allow programmers specify of many real-world usage policies; yet, they are simple enough to permit formal reasoning. Programmers can sandbox untrusted pieces of code with usage policies. The Jalapa tool rewrites the Java bytecode by adding the hooks for the mechanism that enforces the given policies at run-time
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