1. From model to mechanism : enforcing delegated authority in ssi with language-based securityMuhamed Turkanović, Vid Keršič, Alen Horvat, Dominik Beron, Špela Čučko, 2025, izvirni znanstveni članek Opis: Delegation of authority remains a critical yet insufficiently addressed capability in SelfSovereign Identity (SSI) systems. Building on an existing delegation model that introduced the concept of a Verifiable Mandate (VM) for expressing authority and access rights, this paper extends the approach with a rigorous formalization of delegation semantics, enabling unambiguous reasoning over roles, grants, and constraints. The formal model is aligned with standards from the World Wide Web Consortium (W3C), and its constructs are embedded into an extended credential schema that preserves compatibility with the Verifiable Credentials (VC) data model while introducing delegation-specific attributes. A generalized VM schema is defined, supporting both generic and business-specific instantiations, and ensuring structural and semantic interoperability. Policy compliance is operationalized through a policy-based enforcement architecture, where rules are authored in the Rego language and evaluated at runtime by the Open Policy Agent (OPA). The architecture incorporates trusted registries for schema and policy distribution, allowing verifiers to define and enforce context-specific delegation rules in a modular and interoperable manner. Validation through realistic scenarios, such as postal service and academic use cases, demonstrates how formal semantics, schema validation, and language-based policy enforcement can be combined to enable secure, verifiable, and context-aware delegation in SSI ecosystems.
Ključne besede: self-sovereign identity, delegation, verifiable mandate, formalization, policy-based enforcement, verifiable credentials, blockchain, language-based security
Objavljeno v DKUM: 02.10.2025; Ogledov: 0; Prenosov: 9
 Celotno besedilo (1,46 MB) |
2. A review on building blocks of decentralized artificial intelligenceVid Keršič, Muhamed Turkanović, 2025, izvirni znanstveni članek Opis: Artificial intelligence (AI) is one of the key technologies transforming our lives, while the transfer of knowledge and competencies from the academic sphere to the industry and real-world use cases are accelerating yearly. However, during that transition, several significant problems and questions need to be addressed for the field to develop ethically, such as digital privacy, ownership, and control. These are some of the reasons why the currently most popular approaches of artificial intelligence, i.e., centralized artificial intelligence (CEAI), are questionable, with other directions also being explored widely, such as decentralized artificial intelligence (DEAI), which aim to solve some of the most far-reaching problems. This paper aims to review and organize the knowledge in the field of DEAI, focusing solely on studies that fall within this category. A systematic literature review (SLR) was conducted using six scientific databases and additional gray literature to analyze and present the findings of 71 identified studies. The paper’s primary focus is identifying the building blocks of DEAI solutions and networks, tackling the DEAI analysis from a bottom-up approach. Future research directions and open problems are presented and proposed at the end.
Ključne besede: artificial intelligence, blockchain, cryptography, decentralization, AI, DEAI, decentralized artificial intelligence
Objavljeno v DKUM: 23.04.2025; Ogledov: 0; Prenosov: 7
Celotno besedilo (2,83 MB) |
3. |
4. Orchestrating Digital Wallets for On- and Off-Chain Decentralized Identity ManagementVid Keršič, Urban Vidovič, Andraž Vrečko, Martin Domajnko, Muhamed Turkanović, 2023, izvirni znanstveni članek Opis: Digital identity is becoming one of the core elements during the digitalization age, when more and more processes and interactions are taking place in the digital sphere. Therefore, current identity management approaches will define how these interactions will look in the future, but different fields and communities often approach management with their own solutions and tools, despite their similarities. This includes decentralized digital identities, where the identity is managed with asymmetric cryptographic keys, and no centralized entity oversees the whole identity system. This paper focuses on managing on- and off-chain decentralized digital identities, with the former being used for blockchain networks and the latter for self-sovereignty and privacy. While both types of decentralized identity build on the same cryptographic and identity primitives, there is no single wallet that handles both. Therefore, this paper proposes an orchestration solution for both wallet types, which enables their convergence to a single universal wallet and validates it with a real-life decentralized identity use case.
Ključne besede: decentralized identity, self-sovereign identity, wallet, identity, identity management, web3
Objavljeno v DKUM: 13.06.2024; Ogledov: 231; Prenosov: 17
Celotno besedilo (3,25 MB)
Gradivo ima več datotek! Več... |
5. Towards a Catalogue of Self-Sovereign Identity Design PatternsŠpela Čučko, Vid Keršič, Muhamed Turkanović, 2023, izvirni znanstveni članek Opis: Self-sovereign identity (SSI) is a user-centric, decentralised identity approach that provides a means for identification, authentication, and authorisation without the involvement of external entities, responsible for identity provisioning and management in current centralised and federated approaches. In general, the basic building blocks of an SSI system include decentralised identifiers, verifiable credentials, identity wallets, a verifiable data registry, and three main actors: issuer, identity holder, and verifier. Even though the SSI field is dominated by proposals, SSI systems can be implemented in different ways, which is reflected in the absence of a well-defined architecture. Thus, the best implementation is still a matter of research, the requirements of the individual system, and its field of application. However, well-designed and implemented systems are crucial to avoiding failures, speeding up the development process, ensuring high quality, and the broader adoption of SSI solutions. Hence, the main objective of this study was to identify design patterns and good practices of the SSI ecosystems by reviewing and analysing the literature, technical documentation, and existing SSI implementations. Therefore, the study is built on existing knowledge, and presents a comprehensive catalogue of thirty-five SSI design patterns that can serve as a starting point for a possible SSI system design.
Ključne besede: self-sovereign identity, decentralised identity, design patterns, decentralised identifiers, verifiable credentials, blockchain, verifiable data registry, identity wallets
Objavljeno v DKUM: 05.12.2023; Ogledov: 448; Prenosov: 82
Celotno besedilo (2,31 MB)
Gradivo ima več datotek! Več... |
6. Vzorčenje soseščine v heterogenih grafih pri grafovskih nevronskih mrežah : magistrsko deloVid Keršič, 2022, magistrsko delo Opis: Grafovske nevronske mreže so v zadnjem času eno izmed najbolj aktivnih področij raziskovanja globokega učenja. Uspešno so bile uporabljene pri problemih, kjer so podatki predstavljeni v obliki grafa, na primer pri analizi družbenih omrežij, napovedovanju prometa, razvoju zdravil itd. Kljub nekaterim zelo dobrim rezultatom pa ostaja še veliko odprtih izzivov pri uporabi nevronskih mrež na zelo velikih grafih, kjer smo omejeni z zmogljivostjo strojne opreme. V magistrskem delu naslavljamo problem uporabe grafovskih nevronskih mrež na obsežnih heterogenih grafih, kjer se med učenjem izvaja vzorčenje soseščine na vsaki plasti mreže, pri čemer se velikosti vzorca omejijo s hiperparametri. Heterogeni grafi vsebujejo več različnih tipov vozlišč in povezav, kar je pri vzorčenju soseščine koristno upoštevati in optimizirati vrednosti hiperparametrov za posamezne tipe povezav. Za reševanje tega problema predstavimo in analiziramo lasten algoritem, ki odpravi potrebo po časovno zahtevnem procesu obravnavanja in nastavljanja hiperparametrov za vse tipe vozlišč ter povezav. Prednosti algoritma z vidika časovne zahtevnosti in uspešnosti klasifikacije prikažemo na dveh grafih – akademskem grafu MAG240M, ki vsebuje več kot 240 milijonov vozlišč in nekaj manj kot 2 milijardi povezav, ter grafu znanja Freebase.
Ključne besede: umetna inteligenca, strojno učenje, heterogeni grafi, grafovske nevronske mreže
Objavljeno v DKUM: 20.10.2022; Ogledov: 626; Prenosov: 85
Celotno besedilo (1,59 MB) |
7. Metode strojnega učenja za vektorsko vložitev vozlišč grafa : diplomsko deloVid Keršič, 2020, diplomsko delo Opis: Graf je neevklidska podatkovna struktura, ki jo je težko neposredno analizirati z metodami strojnega učenja, ki obdelujejo podatke v vektorski obliki. Zaradi tega so v zadnjih letih postale priljubljene metode strojnega učenja za vektorsko vložitev, ki graf transformirajo v vektorski prostor. V diplomskem delu zgradimo graf iz člankov z angleške Wikipedije s sledenjem vsebovanim hiperpovezavam. Eksperiment izvedemo za filme in glasbene albume. Vozlišča dobljenega grafa vložimo v vektorski prostor, kar nam omogoči učinkovitejšo analizo grafa, pri kateri se osredotočimo na vizualizacijo, podobnost ter klasifikacijo filmov in albumov v žanre. Med seboj primerjamo vložitve metod DeepWalk, node2vec in SDNE. Pri klasifikaciji filmov v povprečju dosežemo 88,5 % točnost, pri albumih pa 89,3 % točnost.
Ključne besede: strojno učenje, graf, vložitev vozlišč, naključni sprehod, avtokodirnik
Objavljeno v DKUM: 04.11.2020; Ogledov: 851; Prenosov: 99
Celotno besedilo (1,89 MB) |
