OEURO is a EUR-denominated clearing token designed for direct account-to-account settlement.It is implemented as a restricted ERC-20 token with 6 decimals and a deliberately narrow functional scope.Its primary purpose is clearing and settlement, rather than market trading or speculative use.Ordinary transfers are designed for direct EOA-to-EOA circulation.The reference implementation disables approve() and transferFrom().Ordinary transfers to smart-contract recipients are rejected. Minting and burning are explicit operations controlled by the manager.Authorized oracles may submit MINT or BURN requests but cannot directly alter token supply.Oracle requests remain valid for 24 hours and must be executed or rejected by the manager.External clearing references are protected against replay through single-use proof handling.The architecture therefore separates attestation authority from final settlement authority.OEURO uses a restricted recipient model for sensitive infrastructure addresses.The reference contract uses OpenZeppelin ERC-20 and Ownable2Step components.Ethereum Sepolia is used as the current public reference testnet environment.This Zenodo archive contains the Solidity source code, ABI, flattened contract and the OEURO technical white paper and audit reference.
Ira Nath, Sanjukta Chatterjee, Rangan Nath, Rumpa Paul · 5 authors
CryptC provides users with secure wallet services to protect their digital cryptocurrency assets as a modern cryptocurrency solution. Multiple platforms can adopt CryptC through the React Native interface while users can enjoy easy access using authentication from Firebase and Firestore for data and security features. Ganache with ethers.js enables the wallet to perform safe blockchain transactions while operating on a local Ethereum blockchain through its Ganache access. Secure compliance requirements are achieved by the platform through its transaction logging system and scalable functionality and biometric asset security measures, and balance update capabilities. The platform features an interface that combines professional and beginner user capabilities through an interactive dashboard, together with horizontal list presentation and user-focused design execution. The DeFi (Decentralized finance) ecosystem tool CryptC provides real-time operation capabilities that outperforms conventional wallet features like PIN base verification, Real-time Ethereum (ETH) transaction, minimalistic mobile-friendly UI etc. Our work provides comprehensive information about CryptC, along with its unique design specification through android App and security protocols, while validating the platform for payments at multiple operational levels.
konstantinos votis, Panagiotis Symeonidis, Centre for Research and Technology Hellas
This deliverable provides an overview of the Digital Product Passport, Distributed Ledger Technology, and blockchain applied to the needs of ALUMIL in order to demonstrate the use of DPPs in the Aluminium industry sector.
Open access
Physical Unclonable Functions (PUFs) and Hardware Security
AbstractData security has become a growing concern for individuals, businesses, and governments because of increasing cyberattacks, data tampering, and unauthorized access in centralized systems. According to the National Institute of Standards and Technology, blockchain technology addresses these challenges by providing a tamper-evident and tamper-resistant distributed ledger that is implemented without a central authority and records transactions across multiple computers. Its decentralized structure eliminates reliance on a single authority, reducing the risk of system failures and targeted attacks. This Article reviews core blockchain security features, including cryptographic protection, decentralization, consensus mechanisms, immutability, transparency, and smart contract security. Cryptographic tools such as hashing and public-private key systems protect data confidentiality, ensure integrity, and verify user identities. Consensus models like Proof of Work, Proof of Stake, and Practical Byzantine Fault Tolerance enable secure transaction validation. The immutability of blockchain records makes unauthorized changes difficult, supporting trust and auditability. The study also examines threats such as 51% attacks, Sybil attacks, private key theft, and smart contract vulnerabilities, and recommends security practices to mitigate these risks. Finally, the Article explores blockchain applications in healthcare, banking, supply chains, voting, and digital identity. The findings indicate that, despite technical and operational challenges, blockchain offers a promising approach to securing digital transactions, protecting sensitive data, and building trust in the digital environment.
This paper explores the evolving landscape of digital currencies, focusing on the contrasting characteristics and implications of Bitcoin, stablecoins, and Central Bank Digital Currencies (CBDCs). While Bitcoin emerged as a decentralized, privacy-focused alternative to traditional financial systems, CBDCs represent a centralized approach to digital money, potentially enabling unprecedented levels of government surveillance and control. Through an analysis of the fundamental differences between these forms of currency, the paper highlights the risks associated with CBDCs, including threats to individual privacy, financial autonomy, and the potential for regulatory overreach. The study also examines the potential consequences of CBDC adoption, such as programmable money and its implications for economic freedom, while considering the broader impact on the global financial system. Ultimately, this paper argues that while CBDCs are often promoted as a more efficient and secure means of digital transactions, they pose significant dangers that could undermine the principles of decentralization and privacy championed by cryptocurrencies like Bitcoin.
Кваліфікаційна робота бакалавра складається зі вступу, чотирьох розділів, висновків, списку використаних джерел та додатків. Перший розділ кваліфікаційної роботи присвячено дослідженню актуального стану досліджуваної проблематики, обґрунтуванню обраного напряму роботи, а також визначенню та відбору методів і засобів проектування. У другому розділі розглянуто та обґрунтовано підходи й технології для вирішення поставлених завдань. Також наведено функціонально-структурну схему об’єкта проектування та ER-діаграму бази даних. Третій розділ охоплює безпосередню розробку програмного забезпечення та практичне втілення проєктованого об’єкта. Четвертий розділ містить SEO-оптимізацію інформаційно-комп’ютерної системи. У висновках підсумовано результати, отримані в ході виконання всіх попередніх розділів роботи.
This thesis presents the design and implementation of a mobile application for the Android platform aimed at advanced Bitcoin asset management. Its main features are support for multisignature transactions in an M-of-N scheme according to the BIP-48 and BIP-67 standards, and a coin control feature for manual selection of transaction outputs, allowing the user to optimize fees and preserve privacy. A key security element is the integration of the Trezor hardware wallet via the Trezor Connect protocol; private keys never leave the device. The PSBT format (BIP-174) is used to distribute partially signed transactions among cosigners; the application supports native SegWit addresses P2WP- KH and P2WSH. The backend is implemented as a set of microservices in Kotlin/Ktor, the frontend is a native Android application built with Jetpack Compose. Functionality was verified by unit tests of key components and by an end-to-end multisig scenario on the Bitcoin testnet.
This bachelor’s thesis deals with the topic „ Bitcoin – inception, development, future “, focusing on the operating principles of Bitcoin and the blockchain technology that underpins it. The theoretical part explains the key concepts related to cryptocurrencies and then characterizes Bitcoin, including its origin, the mining mechanism, and the significance of halving. The thesis also discusses altcoins, alternative cryptocurrencies that emerged after Bitcoin. The thesis includes an analysis of Bitcoin’s historical price development and identifies selected factors that have influenced its price cycles, volatility, and investor sentiment. Subsequently, it presents a fundamental analysis of Bitcoin, taking into account its specifics as an asset without traditional cash flow, and draws on selected market and on-chain metrics as well as qualitative project factors. A separate chapter is devoted to the regulatory environment in selected jurisdictions and its impact on the market.
Cryptocurrency networks operate on decentralized systems that require efficient performance monitoring for transparency, security, and real-time insights. The establishment of a frontend-only, lightweight dashboard for displaying network metrics linked to popular digital currencies is addressed in this research paper. It collects live data from public APIs and visualizes key performance indicators such as token prices, transaction volume, and ownership distribution using open-source tools like Chart.js. The design emphasizes responsiveness, usability, and data accessibility, targeting users interested in monitoring trends and network health without backend dependencies. This dashboard simplifies data interpretation for end- users and promotes real-time decision-making.
Asset fragmentation across multiple blockchains makes it difficult for users to get a clear overview of their complete portfolio, especially when holdings are spread across multiple wallets. This thesis details the creation of NextNonce, a mobile application designed to solve this specific problem. NextNonce provides an intuitive interface for users to add multiple wallet addresses and monitor all their tokens in one place. A key feature simplifies portfolio management by aggregating the balance of the same token from different blockchains into a single, unified view. The project resulted in a mobile application for both Android and iOS that offers a simple and secure way to track a multi-wallet, multi-blockchain cryptocurrency portfolio.
Diplomski rad detaljno opisuje razvoj Crypto Dashboard aplikacije s naglaskom na integraciju s Bitcoin mrežom i novčanikom (engl. wallet). Glavni cilj rada je implementacija blockchain explorera koji omogućuje korisnicima detaljan uvid u kriptovalute, transakcije, bitcoin novčanik i trenutno stanje na mreži. Korištene tehnologije uključuju ReactJS za frontend sučelje, TypeScript za sigurnost tipova podataka, NodeJS za implementaciju poslužiteljske logike te PostgresSQL kao bazu podataka za pohranu podataka. Kroz ovaj rad demonstriran je proces dizajna i implementacije različitih funkcionalnosti aplikacije, uključujući registraciju i prijavu korisnika, pregled kriptovaluta, interaktivne grafove i grafikone, vijesti i analize, konverziju valuta te specifične informacije o Bitcoinu i njegovom mempoolu. Detaljno je objašnjena i struktura projekta, uključujući organizaciju korisničkog sučelja i backend komponenti te način korištenja testnet poslužitelja za razvoj i testiranje aplikacije. Jedan od ključnih dijelova aplikacije je implementacija sustava za slanje transakcija. Korištenjem Bitcoin testnet mreže simulirane su stvarne transakcije, a sustav koristi Bitcoin Core API biblioteku za upravljanje ključevima, stvaranje transakcija te njihov prijenos unutar mreže.
Mike Graf, Ralf Küsters, Daniel Rausch, Simon Egger · 6 authors
Bulletin boards (BB) are important cryptographic building blocks that, at their core, provide a broadcast channel with memory. BBs are widely used within many security protocols, including secure multiparty computation protocols, evoting systems, and electronic auctions. Even though the security of protocols crucially depends on the underlying BB, as also highlighted by recent works, the literature on constructing secure BBs is sparse. The so-far only provably secure BBs requiretrusted components and sometimes also networks without message loss, which makes them unsuitable for applications with particularly high security needs where these assumptions might not always be met. In this work, we fill this gap by leveraging the concepts of accountability and universal composability (UC). More specifically, we propose the first ideal functionality for accountable BBs that formalizes the security requirements of such BBs in UC. We then propose Fabric*BBas a slight extension designed on top of Fabric*, which is a variant of the prominent Hyperledger Fabric distributed ledger protocol, and show that Fabric*BBUC-realizes our ideal BB functionality. This result makes Fabric*BBthe first provably accountable BB, an often desired, but so far not formally proven property for BBs, and also the first BB that has been proven to be secure based only on standard cryptographic assumptions and without requiring trusted BB components or network assumptions. Through an implementation and performance evaluation we show that Fabric*BBis practical for many applications of BBs.
Web3 predstavlja revolucionarnu promjenu internetskog okruženja, s fokusom na decentralizaciji, sigurnosti i korisničkoj kontroli. Ovaj rad istražuje osnovne aspekte Web3, uključujući glavne tehnologije, vrste aplikacija koje se razvijaju, trenutne zabrinutosti i izazove. Analizom tih elemenata, rad će osvijetliti kako Web3 oblikuje budućnost interneta i kako može poboljšati digitalna iskustva, ali i istražiti potencijalne rizike i izazove.
Blockchain tehnologija temeljena na distribuiranim sustavima omogućava postizanje vrlo visokog stupnja povjerenja, a u njezinoj pozadini leže kriptografski mehanizmi. Najbitniji od njih su simetrična enkripcija, asimetrična enkripcija, kriptografske hash funkcije i digitalni potpisi. Izmjena kriptovaluta, kao što su Bitcoin i Ether, temelji se na pametnim ugovorima koji omogućuju uspješno izvršavanje transakcija, a svaka transakcija iza sebe krije resurse potrebne za njezino pokretanje i postavljanje na mrežu za kojeg se mora plaćati naknada. U okviru završnog rada razvijena je web aplikacija koja omogućuje izvršavanje transakcija na Ethereum mreži, a povezana je na e-novčanik MetaMask koji se dodaje kao ekstenzija internet preglednika Google Chrome. Programski jezik Solidity korišten je za razvoj i provođenje pametnih ugovora, a biblioteka React poslužila je za kreiranje komponenti koje grade interaktivno korisničko sučelje.
U ovom diplomskom radu analiziran je ekosustav zamjene tokena na Ethereumovoj mreži uz primjer implementacije agregatora mjenjačnica. Opisani su pojmovi blok-lanca, kriptovaluta, Ethereuma, decentraliziranih aplikacija, pametnih ugovora, centraliziranih i decentraliziranih mjenjačnica, arbitraže i agregatora mjenjačnica. Objašnjene su prednosti i nedostatci centraliziranih i decentraliziranih mjenjačnica. Uspoređena je instanca decentralizirane mjenjačnice i agregatora mjenjačnica te je posebno objašnjeno kako različite mjenjačnice funkcioniraju. Opisana je i objašnjena trgovina različitim valutama s komponentom pronalaska najpovoljnije zamjene s mogućnošću korištenja valuta koje se ne nalaze direktno u zamjeni. Na kraju je opisan primjer agregatora mjenjačnica koji je implementiran pomoću pametnih ugovora na mreži Ethereum s funkcionalnošću pronalaska najpovoljnije zamjene preko USDC tokena.
The aim of this thesis is to explore the price dynamics of Bitcoin and Ethereum with special emphasis on the role of transaction fees, which can provide insight into network congestion and user behaviour, and may also reflect the future economic viability of these networks. Previous research has shown intertwin- ing relationships between variables and suggested possible endogeneity in a cryptoasset environment. For these purposes, a system of two simultaneous equations for transaction fees and price was developed and subsequently esti- mated using the 2SLS method. The analysis covers relationships from both long-term and short-term perspectives. It turns out that the price dynamics of both assets is determined by a diverse mix of fundamental, economic and spec- ulative factors, despite the narrative that the price of cryptoassets is primarily driven by speculative factors. Furthermore, in the context of the fee-price re- lationship, it turned out that the relationship is a priori that the price impacts the fees, however, at some intervals, the opposite relationship is also shown, which is rather an exception. An important contribution could be the finding of a stable positive effect of the total number of active addresses in Bitcoin on transaction fees, which might bring new insights to the...
U završnom radu opisana je izrada web aplikacije napravljene s ciljem olakšavanja kupnje i prodaje kriptovaluta, odnosno Bitcoina. Omogućen je jednostavan pregled povijesti tržišne cijene i trenutne tržišne cijene Bitcoina, kreiranje narudžbi za kupnju i prodaju po trenutnoj cijeni te kreiranje narudžbi koje će se ispuniti ako cijena dosegne vrijednost koju je korisnik unaprijed odredio. Izrađena je registracija korisnika i prijava za njihovu autentikaciju. Svi korisnici imaju pristup podacima o svom profilu, odnosno podacima o provedenim i trenutno aktivnim narudžbama s njihovog korisničkog računa, te mogućnost otkazivanja trenutno aktivnih narudžbi. Također je izrađeno i administratorsko sučelje, preko kojeg se mogu uklanjati korisnici i njihove narudžbe, te pregledavati podaci o narudžbama, zbog čega su u aplikaciji implementirane i uloge korisnika, s ciljem ograničavanja prava običnih korisnika, odnosno onemogućavanja korisnicima koji nisu administratori da mijenjaju podatke kojima ne bi smjeli imati pristup.
U ovom završnom radu opisan je postupak izrade funkcionalnog Bitcoin novčanika. Novčanik je kreiran u razvojnom okruženju Android Studio, programskome jeziku Kotlin, izrađen je za sve uređaje koji imaju operativni sustav Android 10 (API 29) ili više, pisan je u MVVM arhitekturi (engl. Model–view–viewmodel), a za verzioniranje je korišten sustav GitHub. Svrha ovog novčanika je primanje i slanje bitcoina na glavnoj i testnoj mreži te pregled povijesti transakcija. Za pohranjivanje privatnih i javnih ključeva i ostalih osjetljivih podataka se koristi android keystore i shared preferences. Podatci koji se dohvaćaju s lanca blokova (engl. Blockchain) se pohranjuju u SQLite bazu podataka na uređaju. Vizualno sučelje aplikacije je izrađeno u XML-u kroz razvojno okruženje Android Studio.
The articles in this special section focus on distributed ledger technologies (DLT). DLT, of which blockchain is a popular example, are increasingly becoming a popular means to maintain transactional integrity and achieve consensus among competing parties in many modern distributed data exchanges. Indeed, a Gartner survey estimates that by 2020, DLT and blockchain will support the global movement and tracking of $2 trillion of goods and services annually. Unlike centralized files and databases, distributed ledgers rely on peering nodes to record, share, and synchronize transactions and data in their individually maintained local ledgers. In the case of blockchain, information is organized into blocks that are securely and transparently chained together. These blocks become immutable global knowledge among all peers using consensus algorithms to achieve data synchronization. The “append-only, globally accepted” transactions supported by blockchain technologies have given rise to both opportunities and challenges compared to traditional data storage systems. One of the challenges faced by current information sharing systems, and a key concept that makes DLT appealing is the support for the creation of large scale systems from nodes and components that do not trust each other. Being able to reach consensus and share a commonly verifiable ledger is a very powerful primitive, which is already being considered for data sharing applications in energy, pharmaceuticals, and many other domains.
SELECTED ASPECTS OF BITCOIN AND ITS IMPLICATIONS FROM THE STANDPOINT OF THE LAW AND ECONOMICS Abstract Bitcoin is one of the best-known examples of a decentralized convertible cryptocurrency based on blockchain technology. The diploma thesis deals with the main aspects of bitcoin and bitcoin payment networks in complex economic analysis based on the use of standard economic apparatus. The economic analysis is backed by a thorough and relevant legal research. The main goal of the diploma thesis is complex economic and legal analysis of bitcoin. In economic analysis, the emphasis is put on the use of supply-demand analysis, which outlines the basic factors affecting supply and demand for bitcoins. Based on a clear delineation of these factors, the thesis is able to analyse specific aspects of bitcoin. Diploma thesis analyzes the impacts of decentralized setting, as well as risks associated with anonymity of users, crime in connection with bitcoin, time delays in transaction verification, technical and energetic demands on mining, high transaction costs and internet connection needs. Each of these aspects is compared to existing payment institutions or systems. The thesis also examines the legal regulation of bitcoin. Due to the absence of a complex legal regulation, the diploma thesis tries to apply the...