The popularity of blockchain technology has bootstrapped many “Web3” applications, e.g., Ethereum and IPFS, that apply distributed ledger technology to store transactions. The amount of transactions generated and stored in such Web3 applications is significant and, in its raw form, usually not searchable by users. Existing Web3 transaction indexing and search engines are predominantly centralized and, therefore, can manipulate search results or censor particular queries. With the proliferation of Web3 transactions and applications, a decentralized and censorship-resistant search primitive is becoming essential. We present DESCAN, a decentralized and censorship-resistant indexing and search engine for Web3. Users index their local Web3 transactions using custom rules that output triplets. Generated triplets are bundled in a distributed transaction graph that is searchable by other users. To coordinate search and distribute the storage of the transaction graph over peers in the network, we build upon a Skip Graph (SG) data structure. Since the Skip Graph does not provide any resilience against adversarial peers that censor searches, we propose four modifications to improve its robustness. We implement DESCAN and conduct experiments with up to 12 800 peers and 10 million Ethereum transactions. Our experiments show that DESCAN with our modifications enabled can tolerate 20% adversarial peers and 35% unresponsive peers without disruption. Moreover, we find that searches in DESCAN are usually completed well within a second, even when the network grows. Finally, we show that storage and network costs are evenly distributed amongst peers as the network grows.

Manipulation of user transactions by miners in permissionless blockchain systems is a growing concern. This problem is a pervasive and systemic issue that incurs high costs for users of decentralised applications and is known as Miner Extractable Value (MEV). Furthermore, transaction manipulations create other issues such as congestion, higher fees, and system instability. Detecting transaction manipulations is difficult, even though it is known that they originate from the pre-consensus phase of transaction selection for building blocks, at the base layer of blockchain protocols. In this paper, we summarize known transaction manipulation attacks. We present LO, an accountable base layer protocol designed to detect and mitigate transaction manipulations. LO is built around the accurate detection of transaction manipulations and assignment of blame at the granularity of a single mining node. LO forces miners to log all the transactions they receive into a secure mempool data structure and to process them in a verifiable manner. Overall, LO quickly and efficiently detects censorship, injection or re-ordering attempts. Our performance evaluation shows that LO is also practical and only introduces a marginal performance overhead.

The landscape of electronic marketplaces has been monopolized by a handful of market operators that have accumulated tremendous power during the last decades. This trend raises concerns about fairness and market manipulation by these operators acting as gatekeepers. These concerns have recently been outlined in the EU Digital Markets Act (DMA). In this work, we highlight how technological logic of separation understood in the framework of decentralization can address manipulation concerns. As a first step, we devise a reference model of electronic marketplaces, containing six functional components, and outline how control over these components enables different manipulative practices by gatekeepers. We identify two dimensions of decentralization that can counterbalance monopolistic abuse of marketplace components. We then present a software implementation of our reference model and demonstrate how decentralization and unbundling of market components can alleviate manipulation and fairness concerns. We end our work with a review of related approaches and conclude that modular and interoperable marketplaces can enable an open ecosystem of fair electronic markets envisioned by the DMA.

In this paper, we explore solution directions for the implementation of Safe by Design (SbD) in safety regimes for academic experimentation. SbD is a dynamic and anticipatory strategy for safety regulation in academic research. In this strategy, safety is taken in a broader sense including not only issues of technical precaution of avoiding risks of experimentation but also the societal responsibility of researchers and research institutes of identifying possible future risks. In our research, we have interviewed academic researchers from different disciplines and university support personnel about the factors that enable and limit the possibilities of researchers to implement SbD in safety regimes for experimentation. We articulate our findings in terms of a core set of research values and in terms of conflicts between safety and these research values. And we argue that tools for resolving value conflicts as originating in design for values research can provide directions to solve the value conflicts, and thus help academic researchers to adopt SbD in their experimentation.

The paper examines some of the competing normative claims surrounding the development of Identity Management (IM) systems in general and Self-Sovereign Identity (SSI) systems in particular. It is argued that SSI developments should be assessed against the backdrop of IMs attempting to implement a global identity layer based on aggregated singular identities and reputation scores. It is also argued that this trend defines key ethical issues pertaining to the development of SSI systems. In order to explicate and evaluate these issues, the paper looks at the desirability of singular aggregated identities through the lens of moral-philosophical theories. It is argued that such an analysis strongly suggests moral desirability of a plural identities approach in SSIs that have built-in advantage for the implementation of the practical separation of identities.

Self-sovereign identity (SSI) solutions implemented on the basis of blockchain technology are seen as alternatives to existing digital identification systems, or even as a foundation of standards for the new global infrastructures for identity management systems. It is argued that ‘self-sovereignty' in this context can be understood as the concept of individual control over identity relevant private data, capacity to choose where such data is stored, and the ability to provide it to those who need to validate it. It is also argued that while it might be appealing to operationalise the concept of ‘self-sovereignty’ in a narrow technical sense, depreciation of moral semantics obscures key challenges and long-term repercussions. Closer attention to the normative substance of the ‘sovereignty’ concept helps to highlight a range of ethical issues pertaining to the changing nature of human identity in the context of ubiquitous private data collection.

New network technologies are framed as eliminating ‘transaction costs’, a notion first developed in economic theory that now drives the design of market systems. However, the actual promise of the elimination of transaction costs seems unfeasible, because of a cyclical pattern in which network technologies that make that promise create processes of institutionalization that create new forms transaction costs. Nonetheless, the promises legitimize the exemption of innovations of network technologies from critical scrutiny.

This paper looks at the development of blockchain technologies that promise to bring new tools for the management of private data, providing enhanced security and privacy to individuals. Particular interest presents solutions aimed at reorganizing data flows in the Internet of Things (IoT) architectures, enabling the secure and decentralized exchange of data between network participants. However, as this paper argues, the promised benefits are counterbalanced by a significant shift towards the propertization of private data, underlying these proposals. Considering the unique capacity of blockchain technology applications to imitate and even replace traditional institutions, this aspect may present certain challenges, both of technical and ethical character. In order to highlight these challenges and associated concerns, this paper identifies the underlying techno-economic factors and normative assumptions defining the development of these solutions amounting to technologically enabled propertization. It is argued that without careful consideration of a wider impact, such blockchain applications could have effects opposite to the intended ones, thus contributing to the erosion of privacy for IoT users.

This paper argues that the practical implementation of blockchain technology can be considered an institution of property similar to legal institutions. Invoking Penner's theory of property and Hegel's system of property rights, and using the example of bitcoin, it is possible to demonstrate that blockchain effectively implements all necessary and sufficient criteria for property without reliance on legal means. Blockchains eliminate the need for a third-party authority to enforce exclusion rights, and provide a system of universal access to knowledge and discoverability about the property rights of all participants and how the system functions. The implications of these findings are that traditional property relations in society could be replaced by or supplemented with blockchain models, and implemented in new domains.