Contrat intelligent

Les contrats intelligents (en anglais : smart contracts) sont des protocoles informatiques qui facilitent, vérifient et exécutent la négociation ou l'exécution d'un contrat, ou qui rendent une clause contractuelle inutile (car rattachée au contrat intelligent). Les contrats intelligents ont généralement une interface utilisateur et émulent la logique des clauses contractuelles. Cependant, les contrats intelligents sont du code informatique, et si l'interface utilisateur venait à disparaître, il serait toujours possible d'interagir avec ceux-ci. Seul un arrêt du réseau sur lequel les contrats intelligents sont hébergés pourrait mener à son inaccessibilité. Les partisans des contrats intelligents affirment que de nombreux types de clauses contractuelles peuvent ainsi être partiellement ou totalement auto-exécutées ou exécutées à la validation ou les deux. Les contrats intelligents visent à assurer une sécurité supérieure à la mise en application de la loi sur les contrats et de rédu

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Publications associées (9)

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Contracts for Real-Time, Safety Critical Systems

Chandrakana Nandi

Verifying real-time systems goes beyond the verification of functional properties: it also requires the checking of real-time properties. This makes traditional contract-frameworks partially inept for checking real-time programs. This is a major problem because the failure of real-time and safety critical systems can have serious consequences. This thesis presents a solution to this problem by incorporating Design by Contract (annotating programs with function pre and post conditions) to such systems. The main contribution of this thesis is the development of a contract framework for cyclic real-time control applications written in C++. The contract framework allows the users to specify both functional and temporal properties for the applications. A novel approach of empirical cumulative distribution function (cdf ) based statistical inference is used for dynamically estimating temporal constraints and incorporating them in future contracts. The thesis also illustrates the use of Real-time Logic (RTL) for formal specification of the temporal properties. For evaluating our methodology, we have integrated it to a component-based framework called FASA (Future Automation System Architecture) developed at ABB Corporate Research for writing hard real time control applications. Experiments show that this contract framework can be smoothly integrated to existing control applications thereby increasing their reliability while having a acceptable overhead (less than 10%) on the performance.

2014

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Rethinking General-Purpose Decentralized Computing

Enis Ceyhun Alp, Bryan Alexander Ford, Georgia Fragkouli, Eleftherios Kokoris Kogias

While showing great promise, smart contracts are difficult to program correctly, as they need a deep understanding of cryptography and distributed algorithms, and offer limited functionality, as they have to be deterministic and cannot operate on secret data. In this paper we present Protean, a general-purpose decentralized computing platform that addresses these limitations by moving from a monolithic execution model, where all participating nodes store all the state and execute every computation, to a modular execution-model. Protean employs secure specialized modules, called functional units, for building decentralized applications that are currently insecure or impossible to implement with smart contracts. Each functional unit is a distributed system that provides a special-purpose functionality by exposing atomic transactions to the smart-contract developer. Combining these transactions into arbitrarily-defined workflows, developers can build a larger class of decentralized applications, such as provably-secure and fair lotteries or e-voting.

ASSOC COMPUTING MACHINERY2019

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Malware in the SGX supply chain: Be careful when signing enclaves!

Pascal Felber, Rafael Pereira Pires

Malware attacks are a significant part of the new software security threats detected each year. Intel Software Guard Extensions (SGX) are a set of hardware instructions introduced by Intel in their recent lines of processors that are intended to provide a secure execution environment for user-developed applications. To our knowledge, there was no serious attempt yet to overcome the SGX protection by exploiting the weaknesses in the software supply chain infrastructure, namely at the level of the development, build or signing servers. While SGX protection does not specifically take into consideration such threats, we show in the current paper that a simple malware attack exploiting a separation between the build and signing processes can have a serious damaging impact, practically nullifying SGX integrity protection measures. We also explore two possible mitigations against the attack, one centralized leveraging SGX itself, and one distributed that relies on a smart contract deployed on a blockchain infrastructure. Our evaluation shows that both methods are feasible in practice and their added costs are acceptable for the offered protection.

2020

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FIN-413: Financial applications of blockchains and distributed ledgers

This course provides an introduction to distributed ledger technology, blockchains and cryptocurrencies, and their potential applications in finance and banking.

CS-438: Decentralized systems engineering

A decentralized system is one that works when no single party is in charge or fully trusted. This course teaches decentralized systems principles while guiding students through the development and testing of their own decentralized system incorporating messaging, encryption, and blockchain concepts.

COM-402: Information security and privacy

This course provides an overview of information security and privacy topics. It introduces students to the knowledge and tools they will need to deal with the security/privacy challenges they are likely to encounter in today's Big Data world. The tools are illustrated with relevant applications.

Ethereum

Ethereum (prononcé ) est un protocole d'échanges décentralisés permettant la création par les utilisateurs de contrats intelligents. Ces contrats intelligents sont basés sur un protocole informatique

Bitcoin

Le 'Bitcoin' (₿, BTC, XBT) (de l'anglais bit : unité d'information binaire et coin ) est une cryptomonnaie autrement appelée monnaie cryptographique. Dans le cas de la

Blockchain

vignette|redresse|Représentation d’une chaîne de blocs. La chaîne principale (en noir) est composée de la plus longue suite de blocs après le bloc initial (vert). Les blocs orphelins sont représentés