The principle of financial independence is particularly linked to one of the budgetary principles, i.e. the principle of material unity. The article aims to describe the principles of financial independence and the principle of material unity in the financing of municipalities. To obtain this objectives, we focus on explaining the essence and goals of the principles of financial independence and the principles of material unity, as well as on exceptions to the principles of unity. The article bases on the dogmatic and legal method. The presented considerations lead to the conclusion that the introduction of many sources of exceptions to the principles of material unity results from additional regulatory arbitrariness, limiting decentralization and management independence.
Дмитро Люшенко, Нодарі Горгіладзе, Олександр Туголуков, Михайло Шептун · 6 authors
Висока волатильність криптовалют та швидке поширення технологій штучного інтелекту (ШІ) у фінансовому секторі визначають необхідність точного прогнозування ризиків і поведінки інвесторів у процесі цифрової трансформації фінансових ринків. Метою дослідження є розробка системи економетричних моделей для оцінки прибутковості, волатильності, ліквідності та ризику падіння основних криптоактивів із використанням методів на основі ШІ. Методологічна структура включає моделі специфікацій ARDL-MIDAS, GARCH-MIDAS, PMG та logit, які поєднують високочастотні ринкові дані, макроекономічні індикатори, он-чейнгові метрики та індекси настроїв інвесторів. Вибірка охоплює вторинні дані за 2018-2025 роки для п'яти провідних активів — Bitcoin, Ethereum, BNB, XRP та Solana. Результати моделі ARDL-MIDAS показали, що збільшення обсягів торгівлі на 1% збільшує короткострокову прибутковість на 0,012 пункту, водночас зростання індексу VIX зменшує їх на 0,014 пункту. У моделі GARCH-MIDAS коефіцієнти α=0.085 та β=0.900 підтверджували високу інерцію волатильності біткоїна, а компонент MIDAS у VIX мав значний вплив 0.27. Модель панелі PMG виявила негативний довгостроковий вплив волатильності на ліквідність (−0,27) і позитивний ефект надпливу стейблкоїнів (−0,12), що вказує на функцію стабілізації. Логіт-модель довела, що збільшення на стандартне відхилення індексу VIX збільшує ризик краху на 52%. Отримані результати підтверджують ефективність поєднання економетричних методів і ШІ для аналізу цифрових фінансових ринків і технологій ШІ для аналізу цифрових фінансових ринків. Висновки підкреслюють можливість практичного застосування запропонованих моделей у фінансовому прогнозуванні, управлінні ризиками та політиці стабілізації цифрових активів у контексті розробки інтелектуальних фінансових систем на основі ШІ.
As the digital transformation accelerates, the security of cloud-based data storage and transmission has become a critical concern. Traditional cryptographic models often fail to ensure data integrity, privacy, and non-repudiation in distributed environments. This study proposes a blockchain-based security framework that integrates smart contracts, hash-based consensus, and distributed ledger technology (DLT) to enhance cloud data protection. The framework leverages immutable storage for audit trails, consensus validation for tamper detection, and homomorphic encryption for privacy-preserving computations. Experiments using Hyperledger Fabric and Ethereum private testbeds reveal that blockchain integration improves data integrity verification efficiency by 42% and reduces unauthorized modification risks by 35% compared to conventional systems. The findings underscore blockchain’s role as a cornerstone of trustworthy cloud architectures, ensuring both transparency and confidentiality in global digital ecosystems..
Although many academic studies have examined volatility spillovers and dynamic correlations between stock markets, they have largely overlooked the perspective of Small and Medium-Sized Enterprise (SME) markets. On this basis, this study explores the interconnectedness and volatility correlation between Decentralized Finance (DeFi) markets and SME markets. To understand the correlation between these markets, we empirically analyse six European SME market indices—the FTSE AIM All-Share Index (AIM), BIST SME Industrial Index (BISTSME), Euronext Growth All-Share Index (EURONEXT), First North All-Share Index (FIRSTNORTH), IBEX Medium Cap Index (IBEXC), and Scale All-Share Performance Index (SCALE)—alongside three cryptocurrencies: Aave (AAVE), Ethereum (ETH), and Uniswap (UNI); two stablecoins: Dai (DAI) and USD Coin (USDC); and one synthetic asset: Synthetix (SNX). The study employed BEKK-GARCH and DCC-GARCH to analyse the existence of spillover effects and correlations from October 5, 2020, to August 18, 2024. The findings indicate that AAVE, ETH, and UNI, in particular, transmit significant volatility to the EURONEXT and FIRSTNORTH markets. However, bidirectional volatility spillover was detected between EURONEXT and AAVE, ETH, UNI, USDC, and SNX, and FIRSTNORTH and AAVE, ETH, UNI, and SNX. This suggests volatility interdependence between these markets and the existence of potential risk contagion channels.
This study aims to analyze the implementation of smart contracts in digital business practices and to assess their legal certainty from a civil law perspective. This research employs a normative legal research method using statutory and conceptual approaches, focusing on the Indonesian Civil Code, the Law on Electronic Information and Transactions, and the Law on Financial Sector Development and Strengthening. The findings indicate that smart contracts can be legally recognized as valid agreements provided they fulfill the essential requirements of contract validity, namely consent, legal capacity, a specific object, and a lawful cause. However, the automated and code-based nature of smart contracts poses challenges in interpreting the parties’ intent, verifying legal capacity, and determining lawful cause. Therefore, stronger regulatory frameworks and hybrid contract models are necessary to ensure legal certainty for smart contracts in Indonesia.
The intermediated holding of investment securities through tiered custody chains undermines the rights of investors. Distributed ledger technology offers potential solutions through direct investor-issuer connections, but emerging regulatory frameworks paradoxically recreate intermediation while providing weaker safeguards than for traditional securities. This article examines how current legal approaches to tokenised securities risk creating worse outcomes for investors, particularly retail participants.
This study presents a comprehensive bibliometric analysis of blockchain identity management research published between 2010 and 2025, aiming to map its intellectual structure, thematic evolution, and global collaboration patterns. Using data retrieved from the Scopus database and analyzed with VOSviewer, the study applies network visualization, overlay visualization, density mapping, citation analysis, and co-authorship analysis to uncover dominant research streams and emerging frontiers. The results reveal that the field is conceptually centered on blockchain-based authentication and decentralized identity management systems, with increasing scholarly attention toward privacy-preserving mechanisms such as zero-knowledge proofs, anonymity, and data protection. Thematic evolution indicates a clear transition from foundational infrastructure-oriented studies to application-driven and regulatory-sensitive research domains, including e-government, IoT, healthcare, and digital governance. Collaboration analysis highlights the leading role of China and India, supported by strong transcontinental linkages with the United States and European countries, reflecting a globally interconnected yet regionally concentrated research landscape. By systematically mapping publication trends, thematic clusters, and collaboration networks, this study provides a structured knowledge base that supports future theoretical development, guides practical implementation, and informs policy formulation in blockchain-based digital identity ecosystems.
This report examines smart contracts as a key element in the development of decentralized systems and as a factor for a profound transformation of traditional contract law.The analysis focuses on the essence of smart contracts, their technological mechanism of action and the role of cryptography in ensuring trust and security without the need for a central intermediary.Particular attention is paid to the way in which program code begins to perform functions traditionally inherent in legal norms and institutions.Smart contracts are not just a technical tool, but a new socioeconomic mechanism for regulating relations between entities in a digital environment.The report also examines the concept of "Code is Law" as a philosophical and practical framework that questions the classical legal principles of interpretation, flexibility and judicial review.Both the potential benefits of this paradigm and the risks arising from full automation are analyzed.Additionally, the main vulnerabilities of smart contracts that arise as a result of human errors when writing the code and the irreversibility of actions in a blockchain environment are examined.These risks show that technological security does not always mean legal justice.Finally, the legal status of smart contracts in Bulgaria and the European Union is examined.
Open access
Cryptography and Data Security
Advanced Research in Systems and Signal Processing
Deny Prasetyo, Siska Narulita, Ahmad Jurnaidi Wahidin, Rosalina Yani Widiastuti · 7 authors
This study introduces a trust centric machine learning framework designed to improve decision making reliability and security in decentralized digital service ecosystems. Traditional machine learning models often focus on accuracy and efficiency but fail to address the challenges of trust and security in decentralized environments. In contrast, the proposed framework integrates dynamic trust indicators and employs Federated Learning (FL) to ensure privacy while enhancing decision making performance. The framework also incorporates Zero Knowledge Proofp based Verifiable Machine Learning (ZKP-VML), which ensures transparency and security without compromising sensitive data. Through continuous real time trust assessments, the framework adapts to changing conditions, improving the accuracy and reliability of decisions in environments where participants may not fully trust each other. The application of this framework in autonomous vehicles and IoT networks demonstrated its ability to make robust, secure decisions, even in complex and uncertain scenarios. The framework’s ability to incorporate both trust and security into its decision making processes sets it apart from traditional models, which typically do not address the trustworthiness of data or participants. This research highlights the importance of integrating trust and security into machine learning models, particularly in decentralized systems, and offers a robust solution to trust management challenges. However, challenges such as scalability and computational efficiency remain, and future work should focus on enhancing these aspects, along with exploring the framework's applicability in other decentralized domains like finance or supply chain management. The integration of privacy preserving technologies and improvements in adversarial robustness are also potential areas for future research.
Muhammad Abduh Tuasikal, Jaih Mubarak, Ibdalsyah, Yulizar Djamaluddin Sanrego
The rapid growth of cryptocurrency investors in Indonesia has sparked debates about its legal status within Islamic jurisprudence. A key focus is the extreme price volatility of cryptocurrencies and whether this should be classified as gharar (excessive uncertainty) or simply as market risk. This study utilizes a normative-legal and doctrinal approach to differentiate between volatility, an inherent characteristic of modern financial instruments, and gharar, a prohibited element in Islamic contracts. The primary data for this research is sourced from classical fiqh texts and contemporary fatwas, while secondary data includes regulations and indexed academic studies on financial volatility. The findings indicate that although cryptocurrencies display higher volatility compared to stocks and gold, not all fluctuations can be classified as gharar fāḥish (excessive uncertainty). Instead, volatility should be viewed as market risk (al-ghurm), which is measurable, manageable, and tolerable under Islamic law, provided that transparency and risk-sharing mechanisms are in place. The study concludes that cryptocurrencies can be considered lawful property under Islamic law when they are free from ribā (usury), maysir (gambling), and excessive gharar, thereby providing a solid foundation for issuing fatwas and designing regulations.
The article examines the economic nature of local finance and determines its social role under the transformation of Ukraine's public finance system. The study analyzes the historical evolution of local finance in foreign and domestic contexts, revealing a transition from viewing it as a simple community expenditure estimate to recognizing it as a complex instrument for territorial viability and financial independence. The research highlights that while foreign models followed a gradual path toward autonomy, the Ukrainian experience was marked by a long period of centralization within an administrative-command system, which is currently being overcome through fiscal decentralization. The paper systematizes academic approaches to defining "local finance" into five categories: system-resource, functional, economic, socio-economic, and legal. This classification demonstrates the multidimensional nature of local finance as both a component of public finance and the foundation of local self-government. The authors propose an updated definition, describing local finance as an institutionally regulated system of economic relations that ensures the implementation of both own and delegated powers, satisfies public needs, and promotes sustainable socio-economic development. Under the conditions of martial law and the challenges of post-war recovery, local finance is shown to transform from a mere budgetary tool into a strategic mechanism for social stability. The study concludes that the modern social role of local finance is centered on supporting internally displaced persons, ensuring security, and facilitating the recovery of territorial communities, thereby serving as a fundamental element of public finance sustainability.
Andreas KOLYDAS, Stamatis Kontsas, Stavros Kalogiannidis
The research aims to find out how cryptocurrency aids tax evasion in Greece, the socio-economic factors contributing to the practice, and the efficiency of the Greek taxation legislation in deterring such conduct. A total of 359 questionnaires were completed by respondents who engage in cryptocurrencies in Greece. Cross correlational statistical analysis and multiple regression analysis were used to test the relationship of cryptocurrency usage, anonymity, tax policies and socio-economic factors and their impact on tax evasion. Also, sociodemographic factors such as income levels and education levels greatly affected the ability to engage in tax evasion. The study provides a validation that the frequency of cryptocurrency usage, anonymity, ineffectual tax laws, socio-economic factors have a positive correlation with tax evasion rates and influence tax dodging in Greece. Based on the issues highlighted in this study, the following steps are advised for the improvement of the Greek anti-money laundering and combating the financing of terrorism regime: i) improve the regulation and enforcement measures concerning cryptocurrencies, ii) enhance the transparency of the cryptocurrency transactions, and iii) address the socio-economic circumstances that enable tax evasion.
The thriving Non-Fungible Token(NFT) market, despite its innovative redefinition of digital ownership, faces malicious attacks and challenges, notably from widespread wash trading. In this paper, we examine the underexplored relationship between NFT rarity and wash trading.We present a novel approach to NFT market dynamics, by establishing the first comprehensive formal framework for NFT trait systems, including essential definitions, a robust taxonomy, precise rarity calculation, and verifiable properties. Building upon this, we conduct an empirical analysis of NFT rarity and wash trading across 30 collections including 336,133 NFTs, 764,679 transactions, total volume of 14,394,949 in Ethereum. Our findings reveal the strong inverse correlation between a collection’s price-rarity coefficient and its wash trading volume, showing that the top 5 collections with the lowest price-rarity coefficients are overwhelmingly dominated by wash trading, averaging 89.29% of their total volume, in contrast to the vast majority of other collections which exhibited negligible volumes, consistently below 2%. Case studies further highlight the power of this price-rarity analysis as a novel anomaly detection tool: it exposed wash trading-induced distortions in CryptoPunks by detecting an outlier previously undetectable by existing graph-based approaches. We also demonstrate Rektguy’s remarkable resilience—absorbing 20.04% wash volume possibly due to strong rarity-price correlation. Our findings establish rarity as an intrinsic resilience factor against manipulation, fundamentally reshaping approaches to NFT market analysis and robust anomaly detection.
Open access
Blockchain Technology Applications and Security
Physical Unclonable Functions (PUFs) and Hardware Security
Advanced Steganography and Watermarking Techniques
Li Xu, Mohd Nurul Hafiz Ibrahim, Mustafa Muwafak Alobaedy, S. B. Goyal
This is the first PRISMA-guided systematic review of scalable blockchain digital signatures for healthcare, synthesizing evidence from 85 peer-reviewed studies published between 2015 and 2024. The review examines five thematic areas: digital signatures, consensus mechanisms, smart contracts, hybrid blockchain architectures, and regulatory compliance. Particular emphasis is placed on scalability challenges and the role of alternative consensus protocols, such as Proof-of-Stake and Delegated Proof-of-Authority (DPoA), in addressing the energy and latency limitations of Proof-of-Work (PoW). Findings highlight the value of smart contracts in automating consent and authentication processes, while hybrid blockchain models are shown to balance security with scalability. The synthesis also identifies persistent challenges, including interoperability with legacy systems, energy consumption, and compliance with GDPR and HIPAA regulations. Importantly, emerging approaches such as Layer-2 scaling, AI-enhanced validation, and post-quantum cryptography are highlighted as promising directions. By integrating technical and regulatory perspectives, this review contributes a critical roadmap for researchers, healthcare providers, and system architects seeking secure, efficient, and regulation-compliant blockchain frameworks
This article examines the limitations of existing hybrid rollup solutions and presents an adaptive L2 architecture model that leverages artificial intelligence mechanisms. It is shown that current approaches to combining optimistic and ZK verification are largely based on static rules or manual mode selection, which prevents them from effectively accounting for load dynamics, risk profiles, and domain-specific properties of applications. Based on an analysis of optimistic, ZK, and hybrid rollups, an adaptive hybrid rollup model with AI-based transaction routing is proposed. This model combines transaction classification, GNN-based decision making, LSTM-based network condition forecasting, a dual-path execution system, and a continuous learning module. The article describes a Predictive Routing Algorithm that performs proactive selection between ZK and optimistic paths, taking into account cost, latency, security, and risk profile, as well as a Dynamic Resources Allocation mechanism that dynamically redistributes resources between the paths. The proposed multi-criteria optimization framework demonstrates the ability to tune objective weights to the specifics of different classes of DeFi and Web3 protocols. It is shown that the implementation of such a model is promising for systems with high transactional intensity, as it enables a shift from manual configurations to automated, data-driven policies for resource and risk management in hybrid rollup architectures.
The advancement of blockchain technology has introduced new digital economic instruments, notably Non-Fungible Tokens (NFTs), which function not only as representations of digital asset ownership but also as investment vehicles with highly volatile values. This development has sparked debates within Islamic law, particularly regarding the presence of gharar (excessive uncertainty) and maisir (speculative gambling) in NFT investment practices. This study examines the legal status of NFT investment from the perspective of ḥadīth-based muʿāmalah and analyzes the extent to which gharar and maisir are inherent in its transactional mechanisms. Employing a qualitative library research approach, this study uses descriptive-analytical methods to examine Prophetic ḥadīths prohibiting gharar and maisir, and contextualizes them within the technical characteristics and transaction structures of NFTs. Data sources include classical ḥadīth collections, ḥadīth commentaries, fiqh al-muʿāmalah literature, and relevant contemporary scholarly works. The findings indicate that NFTs, as digital assets, possess definable objects, ownership clarity, and verifiable delivery through blockchain technology, and therefore do not inherently constitute gharar. However, the use of cryptocurrency, extreme price volatility, and short-term speculative behavior may introduce elements of gharar and maisir if not accompanied by clear valuation, utility, and investment objectives. Consequently, the permissibility of NFT investment cannot be generalized but must be assessed contextually to uphold justice and the protection of wealth (ḥifẓ al-māl).
Qian'ang Mao, Jiaxin Wang, Liu Ya, Li Zhu · 6 authors
The decentralized architecture of Web3 technologies creates fundamental challenges for Anti-Money Laundering and Counter-Financing of Terrorism compliance. Traditional regulatory technology solutions designed for centralized financial systems prove inadequate for blockchain's transparent yet pseudonymous networks. This systematization examines how blockchain-native RegTech solutions leverage distributed ledger properties to enable novel compliance capabilities. We develop three taxonomies organizing the Web3 RegTech domain: a regulatory paradigm evolution framework across ten dimensions, a compliance protocol taxonomy encompassing five verification layers, and a RegTech lifecycle framework spanning preventive, real-time, and investigative phases. Through analysis of 41 operational commercial platforms and 28 academic prototypes selected from systematic literature review (2015-2025), we demonstrate that Web3 RegTech enables transaction graph analysis, real-time risk assessment, cross-chain analytics, and privacy-preserving verification approaches that are difficult to achieve or less commonly deployed in traditional centralized systems. Our analysis reveals critical gaps between academic innovation and industry deployment, alongside persistent challenges in cross-chain tracking, DeFi interaction analysis, privacy protocol monitoring, and scalability. We synthesize architectural best practices and identify research directions addressing these gaps while respecting Web3's core principles of decentralization, transparency, and user sovereignty.
The real estate sector remains highly dependent on manual document handling and verification, making processes inefficient and prone to fraud. This work presents a system that integrates optical character recognition (OCR), natural language processing (NLP), and verifiable credentials (VCs) to automate document extraction, verification, and management. The approach standardizes heterogeneous document formats into VCs and applies automated data matching to detect inconsistencies, while the blockchain provides a decentralized trust layer that reinforces transparency and integrity. A prototype was developed that comprises (i) an OCR-NLP extraction pipeline trained on synthetic datasets, (ii) a backend for credential issuance and management, and (iii) a frontend supporting issuer, holder, and verifier interactions. Experimental results show that the models achieve competitive accuracy across multiple document types and that the end-to-end pipeline reduces verification time while preserving reliability. The proposed framework demonstrates the potential to streamline real estate transactions, strengthen stakeholder trust, and enable scalable, secure digital processes.
Recording entry and exit records for a country, with properties such as confidentiality, integrity, and auditability, is increasingly important due to rising international mobility and security requirements. Traditional border control systems, which rely on centralised databases, are vulnerable to data manipulation and have limited interoperability between institutions. This study presents GateChain, a blockchain-based application that addresses these vulnerabilities. GateChain aims to enhance data integrity, reliability, and transparency by recording entry and exit events on a distributed, immutable, and cryptographically verifiable ledger. The application provides real-time access control and verification for authorised institutions. This paper describes the architecture and security components of GateChain and evaluates its performance and security features.
Bitcoin derives a verifiable temporal order from probabilistic block discovery and cumulative proof-of-work rather than from a trusted global clock. We show that block arrivals exhibit stable exponential behavior across difficulty epochs, and that the proof-of-work process maintains a high-entropy search state that collapses discretely upon the discovery of a valid block. This entropy-based interpretation provides a mechanistic account of Bitcoin's non-continuous temporal structure. In a distributed network, however, entropy collapse is not completed instantaneously across all participants. Using empirical observations of temporary forks, we show that collapse completion unfolds over a finite propagation-bounded interval, while remaining rapid in practice.
Bitcoin’s price dynamics are influenced by both internal factors (e.g., supply shocks, investor sentiment) and external drivers, among which the stability of stablecoins has attracted increasing academic and regulatory attention. This paper investigates the effect of stablecoin peg deviations (USDT and USDC) on Bitcoin returns using daily data from January 2020 to August 2025. Based on a vector autoregression (VAR) framework, we conduct unit root tests, lag order selection, model estimation, Granger causality tests, and impulse response analysis. Results show that both Bitcoin returns and stablecoin deviations exhibit strong short-term inertia. USDT and USDC deviations significantly Granger-cause Bitcoin returns, whereas the reverse causality is weaker. Impulse responses indicate that stablecoin deviations first produce positive shocks to Bitcoin returns, followed by negative corrections that gradually stabilize. The effect of USDT is more pronounced and persistent, underscoring its central role in cryptocurrency markets. These findings highlight the importance of monitoring stablecoin market stability, especially USDT, for investors and regulators seeking to manage systemic risks in crypto markets.
This article develops a methodological approach to the digital transformation of public administration for sports infrastructure at the regional level under the systemic challenges of martial law. The relevance of this research is determined by the necessity to transition from universal digitalisation models to targeted technological solutions capable of addressing specific institutional dysfunctions within the management system. The aim of this article is to substantiate the methodology of targeted digitalisation as an alternative to comprehensive automation of management processes in the sphere of sports infrastructure. The research combines empirical analysis of management practices with theoretical modelling of digital transformation mechanisms, employing the concept of ‘digital levers’ for organisational change adapted from Westerman, Bonnet, and McAfee’s framework.The study identifies systemic dysfunctions in public administration, including fragmentation of the management hierarchy, deficiency of control mechanisms, limited regional absorptive capacity, and institutional barriers to innovation implementation. Through triangulation of budgetary reporting data, audit conclusions from the Accounting Chamber of Ukraine, and technical documentation from the DREAM digital platform, the research reveals a fundamental disconnect between technological capabilities and institutional readiness for transformation. The developed targeted digitalisation matrix establishes a methodological connection between the characteristics of management pathologies and the functional capabilities of digital technologies. This approach differentiates technological interventions according to three criteria: the nature of dysfunction (structural, procedural, behavioural), the level of digital maturity amongst management entities, and existing resource constraints.The principle of ‘problem-oriented digitalisation’ is substantiated, whereby technologies are selected not for their innovative qualities but for their capacity to influence the reproduction mechanisms of specific management dysfunctions. Each digital instrument is mapped to particular pathology reproduction mechanisms: automation reduces subjective factor influence, distributed ledger technology ensures data immutability, machine learning algorithms optimise resource allocation, and IoT networks provide objective infrastructure monitoring. The research demonstrates that whilst platform-based solutions like DREAM represent technological advancement, their effectiveness remains limited without addressing underlying institutional incentives that perpetuate dysfunctional practices.Prospects for implementing distributed ledger technologies are identified for ensuring transparency of financial flows and automating resource allocation through smart contracts. The study proposes a three-tier implementation architecture: cloud-based solutions for frontline territories lacking local infrastructure, hybrid platforms for regions with moderate capacity, and comprehensive smart ecosystems for developed urban centres. The conclusion is drawn that targeted digitalisation ensures systemic transformation of public administration through precise impact on the reproduction mechanisms of institutional pathologies, unlike universal solutions that merely digitise existing inefficient practices. This methodological approach offers particular value for post-conflict reconstruction contexts where resource constraints demand maximum efficiency in technological investments.