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See detailBlockZoom: Large-Scale Blockchain Testbed
Shbair, Wazen UL; Steichen, Mathis UL; Francois, Jerome et al

in IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2019) (2019, May 14)

Future blockchain applications are anticipated to serve millions of users. Thus the evaluation of new blockchain applications have to consider large-scale assessment of the technologies behind the scene ... [more ▼]

Future blockchain applications are anticipated to serve millions of users. Thus the evaluation of new blockchain applications have to consider large-scale assessment of the technologies behind the scene. Most of current testing approaches have been done either on simulators or via local small blockchain networks. Hence, the performance in real world conditions is unpredictable. This demonstration introduces BlockZoom, a large-scale blockchain testbed that runs on top of a highly reconfigurable and controllable HPC platform. BlockZoom presents a reproducible environment for experimenting distributed ledgers technologies and smart contract applications. Through different configuration scenarios developers can evaluate the applications performance and the blockchain behavior at a scale comparable to the production environment. The target audience of this demonstration includes researchers and developers in blockchain technology. [less ▲]

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See detailDemo: Blockchain for the Simplification and Automation of KYC Result Sharing
Norvill, Robert UL; Steichen, Mathis UL; Shbair, Wazen UL et al

in IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2019) (2019, May 14)

Know Your Customer (KYC) processes performed by banks on their customers are redundant, cumbersome and costly. Therefore, a system is proposed to automate menial tasks and allow sharing of data related to ... [more ▼]

Know Your Customer (KYC) processes performed by banks on their customers are redundant, cumbersome and costly. Therefore, a system is proposed to automate menial tasks and allow sharing of data related to KYC. A blockchain dictates the collaboration between different participants and several services are built around it to support the functionality of the system as a whole. An access control system is used to share data legitimately. [less ▲]

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See detailThe Art of The Scam: Demystifying Honeypots in Ethereum Smart Contracts
Ferreira Torres, Christof UL; Steichen, Mathis UL; State, Radu UL

in USENIX Security Symposium, Santa Clara, 14-16 August 2019 (2019)

Modern blockchains, such as Ethereum, enable the execution of so-called smart contracts - programs that are executed across a decentralised network of nodes. As smart contracts become more popular and ... [more ▼]

Modern blockchains, such as Ethereum, enable the execution of so-called smart contracts - programs that are executed across a decentralised network of nodes. As smart contracts become more popular and carry more value, they become more of an interesting target for attackers. In the past few years, several smart contracts have been exploited by attackers. However, a new trend towards a more proactive approach seems to be on the rise, where attackers do not search for vulnerable contracts anymore. Instead, they try to lure their victims into traps by deploying seemingly vulnerable contracts that contain hidden traps. This new type of contracts is commonly referred to as honeypots. In this paper, we present the first systematic analysis of honeypot smart contracts, by investigating their prevalence, behaviour and impact on the Ethereum blockchain. We develop a taxonomy of honeypot techniques and use this to build HoneyBadger - a tool that employs symbolic execution and well defined heuristics to expose honeypots. We perform a large-scale analysis on more than 2 million smart contracts and show that our tool not only achieves high precision, but is also highly efficient. We identify 690 honeypot smart contracts as well as 240 victims in the wild, with an accumulated profit of more than $90,000 for the honeypot creators. Our manual validation shows that 87% of the reported contracts are indeed honeypots. [less ▲]

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See detailBlockchain-Based, Decentralized Access Control for IPFS
Steichen, Mathis UL; Fiz Pontiveros, Beltran UL; Norvill, Robert UL et al

in The 2018 IEEE International Conference on Blockchain (Blockchain-2018) (2018, July 30)

Large files cannot be efficiently stored on blockchains. On one hand side, the blockchain becomes bloated with data that has to be propagated within the blockchain network. On the other hand, since the ... [more ▼]

Large files cannot be efficiently stored on blockchains. On one hand side, the blockchain becomes bloated with data that has to be propagated within the blockchain network. On the other hand, since the blockchain is replicated on many nodes, a lot of storage space is required without serving an immediate purpose, especially if the node operator does not need to view every file that is stored on the blockchain. It furthermore leads to an increase in the price of operating blockchain nodes because more data needs to be processed, transferred and stored. IPFS is a file sharing system that can be leveraged to more efficiently store and share large files. It relies on cryptographic hashes that can easily be stored on a blockchain. Nonetheless, IPFS does not permit users to share files with selected parties. This is necessary, if sensitive or personal data needs to be shared. Therefore, this paper presents a modified version of the InterPlanetary Filesystem (IPFS) that leverages Ethereum smart contracts to provide access controlled file sharing. The smart contract is used to maintain the access control list, while the modified IPFS software enforces it. For this, it interacts with the smart contract whenever a file is uploaded, downloaded or transferred. Using an experimental setup, the impact of the access controlled IPFS is analyzed and discussed. [less ▲]

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See detailBlockchain Orchestration and Experimentation Framework: A Case Study of KYC
Shbair, Wazen UL; Steichen, Mathis UL; François, Jérôme UL et al

in The First IEEE/IFIP International Workshop on Managing and Managed by Blockchain (Man2Block) colocated with IEEE/IFIP NOMS 2018 (2018)

Conducting experiments to evaluate blockchain applications is a challenging task for developers, because there is a range of configuration parameters that control blockchain environments. Many public ... [more ▼]

Conducting experiments to evaluate blockchain applications is a challenging task for developers, because there is a range of configuration parameters that control blockchain environments. Many public testnets (e.g. Rinkeby Ethereum) can be used for testing, however, we cannot adjust their parameters (e.g. Gas limit, Mining difficulty) to further the understanding of the application in question and of the employed blockchain. This paper proposes an easy to use orchestration framework over the Grid'5000 platform. Grid'5000 is a highly reconfigurable and controllable large-scale testbed. We developed a tool that facilitates nodes reservation, deployment and blockchain configuration over the Grid'5000 platform. In addition, our tool can fine-tune blockchain and network parameters before and between experiments. The proposed framework offers insights for private and consortium blockchain developers to identify performance bottlenecks and to assess the behavior of their applications in different circumstances. [less ▲]

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See detailChainGuard - A Firewall for Blockchain Applications using SDN with OpenFlow
Steichen, Mathis UL; Hommes, Stefan UL; State, Radu UL

in ChainGuard - A Firewall for Blockchain Applications using SDN with OpenFlow (2017)

Recently, blockchains have been gathering a lot of interest. Many applications can benefit from the advantages of blockchains. Nevertheless, applications with more restricted privacy or participation ... [more ▼]

Recently, blockchains have been gathering a lot of interest. Many applications can benefit from the advantages of blockchains. Nevertheless, applications with more restricted privacy or participation requirements cannot rely on public blockchains. First, the whole blockchain can be downloaded at any time, thus making the data available to the public. Second, anyone can deploy a node, join the blockchain network and take part in the consensus building process. Private and consortium blockchains promise to combine the advantages of blockchains with stricter requirements on the participating entities. This is also the reason for the comparably small number of nodes that store and extend those blockchains. However, by targeting specific nodes, an attacker can influence how consensuses are reached and possibly even halt the blockchain operation. To provide additional security to the blockchain nodes, ChainGuard utilizes SDN functionalities to filter network traffic, thus implementing a firewall for blockchain applications. ChainGuard communicates with the blockchain nodes it guards to determine which origin of the traffic is legitimate. Packets from illegitimate sources are intercepted and thus cannot have an effect on the blockchain. As is shown with experiments, ChainGuard provides access control functionality and can effectively mitigate flooding attacks from several sources at once. [less ▲]

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See detailAdvanced Cooling Methods for High-Speed Electrical Machines
Tüysüz, Arda; Meyer, Francesca; Steichen, Mathis UL et al

in IEEE Transactions on Industry Applications (2017)

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See detailAdvanced cooling concepts for ultra-high-speed machines
Tüysüz, Arda; Steichen, Mathis UL; Zwyssig, Christof et al

in Advanced cooling concepts for ultra-high-speed machines (2015)

Detailed reference viewed: 29 (1 UL)