+********************************************************************** * * * Einladung * * * * Informatik-Oberseminar * * * +********************************************************************** Zeit: Freitag, 20. Oktober 2023, 15.30 Uhr Ort: Seminarraum Informatik 4 (COMSYS) - 9007, E3, Ahornstr. 55 [1] Digtaler Zugang (hybrider Vortrag): https://rwth.zoom-x.de/j/69772277508?pwd=SU5qN1FPVXI5V3UwakYydnBUUW1Ldz09 (Meeting-ID: 697 7227 7508 Kenncode: 031824) Referent: Roman Matzutt M.Sc. Lehrstuhl Informatik 4 (COMSYS) Thema: Demystifying and Adjusting the Promises of Blockchain-based Data Management in the Permissionless Setting Abstract: The digital currency Bitcoin introduced the blockchain as a data structure for establishing consensus in a decentralized manner. Since then, blockchain technology generalized to immutably recording arbitrary events and data, now allowing more general online interactions between distrusting users. This interaction model sparked a tremendous interest in blockchain technology, its potential, and applications. However, the identification of multiple shortcomings has since dampened this initial spirit of optimism. Our research focuses on deepening the understanding of these shortcomings, improving upon them, and gauging the true potential for blockchain-backed applications despite these limitations. We take a data-driven perspective to assess the security and longevity of permissionless blockchains, such as Bitcoin, where anybody can access the blockchain's full history and propose new data to be appended. Here, we identify two core challenges: First, the ability of malicious actors to irrevocably append illicit content to a blockchain implies required moderation capabilities despite the desired immutability. Second, the need for massively replicating the full and ever-growing blockchain history poses significant scalability challenges. We tackle these challenges with four contributions. First, we systematically analyze the phenomenon of blockchain content insertion, showing that inserting illicit content can create devastating consequences. Second, we explore means to mitigate these consequences by considering strategies to prevent content insertion and by proposing a new redactable blockchain for the swift and transparent removal of unwanted content. Third, we address the challenge of ever-growing blockchain sizes by proposing a gradually deployable block-pruning scheme that is retrofittable to Bitcoin and enables users to retroactively reduce their storage requirements. Finally, our fourth contribution shows that permissionless blockchains still hold an untapped potential for fueling novel applications by demonstrating how Bitcoin can help securely bootstrapping decentralized anonymity services. Overall, we shed new light on the potential impact of the data persisted on blockchains and widen the scope for resilient and durable blockchain designs for data management tasks. Es laden ein: die Dozentinnen und Dozenten der Informatik [1] https://www.comsys.rwth-aachen.de/fileadmin/misc/how-to-get-to-comsys.pdf