University of Luxembourg

About: University of Luxembourg is a education organization based out in Luxembourg, Luxembourg. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 4744 authors who have published 22175 publications receiving 381824 citations.

SmartCheck: static analysis of ethereum smart contracts

Abstract: Ethereum is a major blockchain-based platform for smart contracts - Turing complete programs that are executed in a decentralized network and usually manipulate digital units of value. Solidity is the most mature high-level smart contract language. Ethereum is a hostile execution environment, where anonymous attackers exploit bugs for immediate financial gain. Developers have a very limited ability to patch deployed contracts. Hackers steal up to tens of millions of dollars from flawed contracts, a well-known example being "The DAO", broken in June 2016. Advice on secure Ethereum programming practices is spread out across blogs, papers, and tutorials. Many sources are outdated due to a rapid pace of development in this field. Automated vulnerability detection tools, which help detect potentially problematic language constructs, are still underdeveloped in this area. We provide a comprehensive classification of code issues in Solidity and implement SmartCheck -- an extensible static analysis tool that detects them. The source code is available at https://github.com/smartdec/smartcheck. SmartCheck translates Solidity source code into an XML-based intermediate representation and checks it against XPath patterns. We evaluated our tool on a big dataset of real-world contracts and compared the results with manual audit on three contracts. Our tool reflects the current state of knowledge on Solidity vulnerabilities and shows significant improvements over alternatives. SmartCheck has its limitations, as detection of some bugs requires more sophisticated techniques such as taint analysis or even manual audit. We believe though that a static analyzer should be an essential part of contract developers' toolbox, letting them fix simple bugs fast and allocate more effort to complex issues.

Satellite Communications in the New Space Era: A Survey and Future Challenges

Abstract: Satellite communications (SatComs) have recently entered a period of renewed interest motivated by technological advances and nurtured through private investment and ventures. The present survey aims at capturing the state of the art in SatComs, while highlighting the most promising open research topics. Firstly, the main innovation drivers are motivated, such as new constellation types, on-board processing capabilities, non-terrestrial networks and space-based data collection/processing. Secondly, the most promising applications are described, i.e., 5G integration, space communications, Earth observation, aeronautical and maritime tracking and communication. Subsequently, an in-depth literature review is provided across five axes: i) system aspects, ii) air interface, iii) medium access, iv) networking, v) testbeds & prototyping. Finally, a number of future challenges and the respective open research topics are described.

The Consequences of Kesterite Equilibria for Efficient Solar Cells

Abstract: Copper−zinc−tin−chalcogenide kesterites, Cu2ZnSnS4 and Cu2ZnSnSe4 (CZTS(e)) are ideal candidates for the production of thin film solar cells on large scales due to the high natural abundance of all constituents, a tunable direct band gap ranging from 1.0 to 1.5 eV, a large absorption coefficient, and demonstrated power conversion efficiencies close to 10%.(1) However, Sn losses through desorption of SnS(e) from CZTS(e) at elevated temperatures (above 400 °C)(2-5) impede the thorough control of film composition and film homogeneity. No robust and feasible fabrication process is currently available. Here we show that understanding the formation reaction of the kesterite absorber is the key to control the growth process and to drastically improve the solar cell efficiency. Furthermore, we demonstrate that this knowledge can be used to simplify the four-dimensional parameter space (spanned by the four different elements) to an easy and robust two-dimensional process. Sufficiently high partial pressures of SnS...

Fully homomorphic encryption over the integers with shorter public keys

Abstract: At Eurocrypt 2010 van Dijk et al. described a fully homomorphic encryption scheme over the integers. The main appeal of this scheme (compared to Gentry's) is its conceptual simplicity. This simplicity comes at the expense of a public key size in O(λ10) which is too large for any practical system. In this paper we reduce the public key size to O(λ7) by encrypting with a quadratic form in the public key elements, instead of a linear form. We prove that the scheme remains semantically secure, based on a stronger variant of the approximate-GCD problem, already considered by van Dijk et al. We alsodescribe the first implementation of the resulting fully homomorphic scheme. Borrowing some optimizations from the recent Gentry-Halevi implementation of Gentry's scheme, we obtain roughly the same level of efficiency. This shows that fully homomorphic encryption can be implemented using simple arithmetic operations.