Conor Flynn, Kristin P. Bennett, John Erickson, Aaron Green ¡ 5 authors
With the agile development process of most academic and corporate entities, designing a robust computational back-end system that can support their ever-changing data needs is a constantly evolving challenge. We propose the implementation of a data and language-agnostic system design that handles different data schemes and sources while subsequently providing researchers and developers a way to connect to it that is supported by a vast majority of programming languages. To validate the efficacy of a system with this proposed architecture, we integrate various data sources throughout the decentralized finance (DeFi) space, specifically from DeFi lending protocols, retrieving tens of millions of data points to perform analytics through this system. We then access and process the retrieved data through several different programming languages (R-Lang, Python, and Java). Finally, we analyze the performance of the proposed architecture in relation to other high-performance systems and explore how this system performs under a high computational load.
Engin Zeydan, Luis Blanco, Josep Mangues, Ĺuayb S. Arslan ¡ 5 authors
Self-Sovereign Identity (SSI) has recently emerged as an identity and access management framework based on Distributed Ledger Technology (DLT) that enables users or organizations to control their own data. The Open RAN (O-RAN), on the other hand, provides a framework for sharing infrastructure-related data between users and mobile network operators (MNOs). By leveraging SSI, O-RAN can benefit from decentralized and secure identity management that enables a more transparent, efficient, and user-centric network ecosystem. This paper examines identity, inventory and configuration management, and authentication of users or MNOs for a resource sharing scenario in an O-RAN architecture. At the end of the paper, we explain the potential limitations and possible solutions for applying SSI to improve security, privacy, trust, and interoperability in O-RANs.
In the rapidly evolving domain of distributed ledger technology, scalability and interoperability have become paramount challenges for both academic and industry sectors. In this paper, we introduce a comprehensive formal model to address atomic composability across multiple rollups on Ethereum. The proposed model incorporates mechanisms like buffering, dependency management, concurrency control, and the groundbreaking zero-knowledge proofs. Moreover, we evaluate its practical repercussions, strengths, and weaknesses, ensuring resilience against manipulative or erroneous actions. The application of the proposed model to shared sequencers and other existing solutions accentuates its versatility and universality.
While increasingly more applications are tempted to manage their data in decentralized systems, such as blockchains or distributed ledgers, the data exchange across multiple, potentially heterogeneous, decentralized systems remains an open problem: State-of-the-art protocols cannot meet one or more of the core requirements, such as atomicity, liveness, and scalability. Specifically, in the field of scientific computing, although a blockchain service was recently developed for scientific computing environments, the data exchanges and transactions among distinct ledgers are not supported. Observing that many modern scientific applications are collaborated on by multiple teams and the increasingly complicated (in-situ) workflows thereof, we argue that there is a pressing need to realize an efficient and scalable protocol for distinct ledgers to exchange data in scientific computing. This paper proposes a topological approach to enabling atomic, nonblocking, and scalable data exchanges among an arbitrary number of scientific ledgers in the context of collaborative scientific computing. Specifically, we construct a topological space formed by these ledgersâabstracting those nodes in a cross-ledger transaction as topological objects such as abstract simplex and simplicial complex. These topological objects, in turn, serve as the building blocks of a topological protocol, namely TopoCommit, under practical assumptions. We implement TopoCommit and integrate it into SciChain, a recently published distributed ledger for tracking scientific data provenance. The extensive evaluation of up to 1,008 nodes and 144 distinct ledgers on CloudLab shows that TopoCommit outperforms state-of-the-art protocols by up to 70Ă.
Blockchain technology relies heavily on consensus mechanisms to ensure the integrity, security, and decentralization of distributed ledgers. This paper provides a comprehensive cryptographic perspective on blockchain consensus algorithms, analyzing their underlying principles, security assumptions, and performance trade-offs. The study focuses on popular consensus protocols including Proof of Work (PoW), Proof of Stake (PoS), and Byzantine Fault Tolerance (BFT) variants, highlighting their cryptographic foundations and vulnerabilities. The paper further discusses emerging consensus designs aimed at enhancing scalability and energy efficiency while preserving cryptographic robustness. Through this analysis, the article aims to guide researchers and practitioners in selecting appropriate consensus protocols for diverse blockchain applications.
Sam Blackshear, Andrey Chursin, George Danezis, Anastasios Kichidis ¡ 12 authors
Sui Lutris is the first smart-contract platform to sustainably achieve sub-second finality. It achieves this significant decrease by employing consensusless agreement not only for simple payments but for a large variety of transactions. Unlike prior work, Sui Lutris neither compromises expressiveness nor throughput and can run perpetually without restarts. Sui Lutris achieves this by safely integrating consensuless agreement with a high-throughput consensus protocol that is invoked out of the critical finality path but ensures that when a transaction is at risk of inconsistent concurrent accesses, its settlement is delayed until the total ordering is resolved. Building such a hybrid architecture is especially delicate during reconfiguration events, where the system needs to preserve the safety of the consensusless path without compromising the long-term liveness of potentially misconfigured clients. We thus develop a novel reconfiguration protocol, the first to provably show the safe and efficient reconfiguration of a consensusless blockchain. Sui Lutris is currently running in production and underpins the Sui smart-contract platform. Combined with the use of Objects instead of accounts it enables the safe execution of smart contracts that expose objects as a first-class resource. In our experiments Sui Lutris achieves latency lower than 0.5 seconds for throughput up to 5,000 certificates per second (150k ops/s with transaction blocks), compared to the state-of-the-art real-world consensus latencies of 3 seconds. Furthermore, it gracefully handles validators crash-recovery and does not suffer visible performance degradation during reconfiguration.
This article presents a token aimed at ensuring the implementation of recurring bill-pay functionality on decentralized platforms utilizing the Ethereum Virtual Machine (EVM). Automatic periodic payments, including subscription-based services, have gained significant traction in traditional fiat-money industries due to the various advantages they offer to both service providers and customers. However, current Distributed Ledger Technologies (DLTs) lack inherent non-custodial mechanisms to support such payment schemes. In this study, we propose an approach implemented through a smart contract that issues tokens on EVM-based networks, enabling the inclusion of recurring payments. This contract ensures compatibility with ERC-20 and ERC-777 standards, offering the potential to establish a novel token standard.
Distributed replication systems that use consensus mechanisms to process clients' requests have major limitations and problems in scalability, throughput, and performance. Such problems are mainly due to the time and message complexity of the consensus algorithms used in such systems. Sharding has already been implemented in several blockchain-based replication systems and although it has shown remarkable potential to improve performance and scalability, yet current sharding techniques have several significant scalability and security issues. In this paper, we propose a novel sharding technique for distributed replication systems that use a consensus to process clients' requests. We modified the approach of how nodes are allocated between shards through the public key generation process. Our approach effectively reduces undesirable cross-shard transactions that are more complex and costly to process than intra-shard transactions. Also, there is no concept of Beacon chain â as a shared-ledger between shards â which imposes additional scalability limitations and security issues on the network. With our approach, a network using a classical distributed consensus algorithm can grow outstandingly in number of nodes and still remain permissionless,
Dmitry A. Zaitsev, Tatiana R. Shmeleva, Zeyu Zhou, Ding Liu
The reliability of consensus protocols establishes the basis for cryptocurrency cybersecurity. Formal and simulation techniques are appreciated for the verification of proof-of-work agreement protocols, because the formal techniques development process frequently requires a series of assumptions, leading to somewhat unrealistic models. A conventional colored Petri net model, presented by the authors in a previous study, allowed us to refine the Keller and BĂśhme consensus protocol by applying the simulation technique. In this study, we developed a reenterable colored Petri net model representing a general construct for model-driven development and refinement of consensus protocols and the corresponding software. A considerable benefit of a reenterable model is the invariance of its structure with respect to the net topology, number of attached nodes, and parameters of their software and hardware, which are represented as the marking of dedicated places. Switching of topology tags associated with dynamic objects represents the basic principle of reenterable model functioning. It is shown that, having the same characteristics, in bounds of admissible error of some 2-3%, the reenterable model results in 6 times speed-up of the simulation process and a drastic decrease in time for model editing, especially when the number of nodes exceeds a hundred. Thus, a reenterable model is a valuable complement to possible formal models that allows us to obtain express-evaluations of characteristics in a rather short time and with an acceptable level of adequacy.
Robert Cowlishaw, Red Boumghar, Ashwin Arulselvan, Annalisa Riccardi
The quantity and diversity of stakeholders in space is increasing and centralised management of their assets is becoming more complex. New technologies in Web3 such as Decentralised Autonomous Organisations (DAOs) can bridge the communication gap with neutral and automated systems, and distribute currently centralised processes that are inherently decentralised by nature. One of these processes is Satellite-based Emergency Mapping (SEM) for Disaster Response Management (DRM). With automated decision strategies and transparent ledgers, a fairer and more accessible system can be built to handle the increase in stakeholders as well as the increasing number of natural disasters occurring. A DAO also address' the key issue with the current SEM process, such as decreasing the current three days wait, required to produce the necessary processed and analysed data for end users, after the disaster occurs. Moreover, with fleets of satellites belonging to different governmental and private organisations, a specific central authority cannot be identified to manage the process in an efficient and equitable way. The paper discusses the need for a more decentralised and automated system for DRM by presenting evidence of current bottlenecks and lays the foundations of the first DAO for on-orbit assets management and demonstrates which Web3 technologies could further improve SEM in this first phase of charter activation.
Digital currencies have become an increasingly popular topic of discussion in recent years. Digital currencies are virtual forms of currency that operate outside the traditional banking system. They are based on cryptographic technologies and are often decentralized, meaning they are not controlled by a central authority. The most well-known digital currency is Bitcoin, but there are many other types of digital currencies in existence. Digital currencies can be used to purchase goods and services online or transferred between users directly without intermediaries like banks. They have gained popularity due to their potential for increased security, transparency, and efficiency in financial transactions. In today's digital currency, a variety of digital currencies emerge in an endless stream, and crypto technology is also constantly developing to improve the security of digital currency payments. In section 2, this paper briefly introduces several common digital currencies and encryption algorithms, and in section 3, this paper introduces these typical digital currencies in detail through the analysis of representative literature. Bitcoin is mainly encrypted based on blockchain technology, and its encryption principle is mainly divided into three parts: public key encryption, hash function, and proof of work. Ethereum is a distributed blockchain platform with encryption principles similar to Bitcoin, including public key encryption and hashing algorithms. Ripple is a distributed cryptocurrency. Its encryption principle mainly adopts the public-private key encryption system. In terms of encryption technology, blockchain technology, the Hash algorithm and symmetric and asymmetric encryption are also popular encryption algorithms in digital currencies.
As a distributed ledger technology, blockchain has found widespread use in a variety of industries, including finance, the Internet of Things (IoT), healthcare, and manufacturing. This technology addresses the trust issue by converting a low-trust centralized ledger into a highly trusted distributed ledger maintained by various entities. Consensus algorithms are one of the fundamental building blocks of the blockchain, controlling how nodes cooperate and synchronize data to perform secure and reliable activities in a decentralized setting. This paper examines the extant mainstream consensus algorithms, introduces six representative consensus algorithms, analyses their benefits and drawbacks, and discusses the application scenarios and suitability of each consensus algorithm in various blockchain platforms.
A distributed and decentralized ledger widely used in the computer science and financial fields called blockchain has provided safe and fast transactions for multiple parties. Also, check the transaction by each node on the blockchain. The consensus mechanism is the core of the blockchain. It lets all the nodes reach an agreement for those transactions, which ensures security and accuracy and make Bitcoin valuable and popular. Two of the most mainstream Consensus mechanisms are Proof of Work (PoW) and Proof of Stake (PoS), and Proof of Authority (PoA) is the new one that will apply in the future. Many discourses talk about consensus mechanisms, most of which are review papers. Those papers mainly show a specific aspect of a consensus mechanism or introduce the primary notion, but they rarely explain the corresponding relationship between theories and cryptocurrency. So, the purpose is to give a clear structure, connect the consensus mechanism to its application and simplify the reader's understanding. This paper aims to provide an overview of the consensus mechanism, including its general definition, concepts of different mechanism variants, and advantages and disadvantages. For the structure below, the essay introduces the notion of consensus mechanism and how PoW, PoS, and PoA work. Then summarize the papers based on these three consensus mechanisms, describing the theories of many consensus mechanisms and comparing the advantages and disadvantages. The essay also creates a comparison table about these three consensus mechanisms to embody the content above the stem better.
The broad topic of this thesis is the design and analysis of Bitcoin custody systems. Both the technology and threat landscape are evolving constantly. Therefore, custody systems, defence strategies, and risk models should be adaptive too. We introduce Bitcoin custody by describing the different types, design principles, phases and functions of custody systems. We review the technology stack of these systems and focus on the fundamentals; key-management and privacy. We present a perspective we call the systems view. It is an attempt to capture the full complexity of a custody system, including technology, people, and processes. We review existing custody systems and standards. We explore Bitcoin covenants. This is a mechanism to enforce constraints on transaction sequences. Although previous work has proposed how to construct and apply Bitcoin covenants, these require modifying the consensus rules of Bitcoin, a notoriously difficult task. We introduce the first detailed exposition and security analysis of a deleted-key covenant protocol, which is compatible with current consensus rules. We demonstrate a range of security models for deleted-key covenants which seem practical, in particular, when applied in autonomous (user-controlled) custody systems. We conclude with a comparative analysis with previous proposals. Covenants are often proclaimed to be an important primitive for custody systems, but no complete design has been proposed to validate that claim. To address this, we propose an autonomous custody system called Ajolote which uses deleted-key covenants to enforce a vault sequence. We evaluate Ajolote with; a model of its state dynamics, a privacy analysis, and a risk model. We propose a threat model for custody systems which captures a realistic attacker for a system with offline devices and user-verification. We perform ceremony analysis to construct the risk model.
Sharding is a critical technique that enhances the scalability of blockchain technology. However, existing protocols often assume adversarial nodes in a general term without considering the different types of attacks, which limits transaction throughput at runtime because attacks on liveness could be mitigated. There have been attempts to increase transaction throughput by separately handling the attacks; however, they have security vulnerabilities. This paper introduces Reticulum, a novel sharding protocol that overcomes these limitations and achieves enhanced scalability in a blockchain network without security vulnerabilities.<br/><br/>Reticulum employs a two-phase design that dynamically adjusts transaction throughput based on runtime adversarial attacks on either or both liveness and safety. It consists of `control' and `process' shards in two layers corresponding to the two phases. Process shards are subsets of control shards, with each process shard expected to contain at least one honest node with high confidence. Conversely, control shards are expected to have a majority of honest nodes with high confidence. Reticulum leverages unanimous voting in the first phase to involve fewer nodes in accepting/rejecting a block, allowing more parallel process shards. The control shard finalizes the decision made in the first phase and serves as a lifeline to resolve disputes when they surface.<br/><br/>Experiments demonstrate that the unique design of Reticulum empowers high transaction throughput and robustness in the face of different types of attacks in the network, making it superior to existing sharding protocols for blockchain networks.
This paper explores the potential for improving blockchain performance through the implementation of an adaptive consensus machine. Blockchains, as immutable distributed ledgers, have found applications in various domains such as cryptocurrency, supply chains, healthcare, and more. The two main types of blockchains are permissionless and permissioned, each with its own advantages and limitations. The proposal suggests monitoring transaction metrics on the blockchain to enable the adaptive machine to adjust operational parameters of the consensus protocol or even switch to a different consensus strategy. This autonomic approach aims to enhance the overall performance of the blockchain by utilizing self-defined policies and goals. The paper discusses the use of off-chain structures for recording transactions and the trade-offs between latency and cost. Furthermore, it highlights the potential improvements that can be achieved by adapting classic consensus algorithms in permissioned blockchains. By incorporating adaptive and autonomic techniques, blockchain platforms can achieve enhanced efficiency and performance.
Zhuo Cai, Soroush Farokhnia, Amir Kafshdar Goharshady, S. Hitarth
Modern programmable blockchains have built-in support for smart contracts, i.e. âprograms that are stored on the blockchain and whose state is subject to consensus. After a smart contract is deployed on the blockchain, anyone on the network can interact with it and call its functions by creating transactions. The blockchain protocol is then used to reach a consensus about the order of the transactions and, as a direct corollary, the state of every smart contract. Reaching such consensus necessarily requires every node on the network to execute all function calls. Thus, an attacker can perform DoS by creating expensive transactions and function calls that use considerable or even possibly infinite time and space. To avoid this, following Ethereum, virtually all programmable blockchains have introduced the concept of âgasâ. A fixed hard-coded gas cost is assigned to every atomic operation and the user who calls a function has to pay for its total gas usage. This technique ensures that the protocol is not vulnerable to DoS attacks, but it has also had significant unintended consequences. Out-of-gas errors, i.e. âwhen a user misunderestimates the gas usage of their function call and does not allocate enough gas, are a major source of security vulnerabilities in Ethereum. We focus on the well-studied problem of automatically finding upper-bounds on the gas usage of a smart contract. This is a classical problem in the blockchain community and has also been extensively studied by researchers in programming languages and verification. In this work, we provide a novel approach using theorems from polyhedral geometry and real algebraic geometry, namely Farkasâ Lemma, Handelmanâs Theorem, and Putinarâs Positivstellensatz, to automatically synthesize linear and polynomial parametric bounds for the gas usage of smart contracts. Our approach is the first to provide completeness guarantees for the synthesis of such parametric upper-bounds. Moreover, our theoretical results are independent of the underlying consensus protocol and can be applied to smart contracts written in any language and run on any blockchain. As a proof of concept, we also provide a tool, called âAsparagusâ that implements our algorithms for Ethereum contracts written in Solidity. Finally, we provide extensive experimental results over 24,188 real-world smart contracts that are currently deployed on the Ethereum blockchain. We compare Asparagus against GASTAP, which is the only previous tool that could provide parametric bounds, and show that our method significantly outperforms it, both in terms of applicability and the tightness of the resulting bounds. More specifically, our approach can handle 80.56% of the functions (126,269 out of 156,735) in comparison with GASTAPâs 58.62%. Additionally, even on the benchmarks where both approaches successfully synthesize a bound, our bound is tighter in 97.85% of the cases.
In this paper, we design, implement, and (partially-) evaluate a lightweight bridge (as a type of middleware) to connect the Bitcoin and Ethereum networks that were heterogeneously uncontactable before. Inspired by the recently introduced Bitcoin Request Comment (BRC-20) standard, we leverage the flexibility of Bitcoin inscriptions by embedding editable operations within each satoshi and mapping them to programmable Ethereum smart contracts. A user can initialize his/her requests from the Bitcoin network, subsequently triggering corresponding actions on the Ethereum network. We validate the lightweight nature of our solution and its ability to facilitate secure and seamless interactions between two heterogeneous ecosystems.
Open access
3 source records
Blockchain Technology Applications and Security
Physical Unclonable Functions (PUFs) and Hardware Security
While blockchain enables decentralized services with zero trust, every node needs to store continuously generating block information in their local storage. Because blocks are generating continuously in blockchain, there exists a significant storage space burden on each node. A typical technique is to introduce a special node customized for block archiving. In case of Ethereum, a special node called block archive node to store all historical blocks. With the help of block archive node, each full node is enough to maintain only latest 128 blocks. In this paper, we propose BSS, an efficient block storage system for block archive service in blockchains, which can support any blockchain including Ethereum. BSS is a distributed system consisting of some number of block archive nodes. The storage overhead of BSS is O(1). The main idea is to encode each block into several small chunks and enforce each archive node to store one chunk, not an entire block. BSS also supports Byzantine tolerant chunk storage protocol for possible Byzantine attacks by block archive nodes. It is shown from the experiments on AWS, BSS enables both substantial block availability and notable performance even in Byzantine attacks.
In this article, we consider DAG-based distributed ledger technologies (DLTs), i.e., DLTs where each block can reference several previous blocks hence forming a directed acyclic graph of blocks (BDAG). Each block has a weight (usually a constant normalized to one) and our goal is to compute the heaviest sub-BDAG that does not contain conflicting blocks. First, we prove that computing such a sub-BDAG is NP-complete. Then, we show that the difficulty comes from concurrent conflicts and we present an optimal algorithm that is polynomial if the number of concurrent conflicts is bounded. We also give an efficient incremental version of our algorithm. Finally, we evaluate the performance of our algorithm on random BDAGs against an existing algorithm called GHOSTDAG and show that, in addition to being optimal, our algorithm is also more efficient in practice.
In Antarctica, many studies in various fields are conducted every year. Some of these studies use sensors to collect relevant data for scientific research. However, Antarctica's lack of communication resources makes it difficult to automate this data collection. In most cases, this collection is done manually and the time and space of the study are limited. Over the past few years, several alternatives for deploying remote wireless sensor networks in Antarctica have been explored. Therefore, in this paper, the analysis of the delay-tolerant network was performed based on the partial Î-synchronized proof-of-stake (PoS) blockchain model. 82% (=1-1/(2e)) of active honest nodes must satisfy the quorum to ensure the security of the proof-of-stake blockchain. If the adversary has less than 18% of the total stake and sets the overall growth rate low, the longest chain protocol is secure. However, as Nakamoto argues in proof-of-stake blockchain protocols, an adversary cannot secure the longest-chain protocol at less than 50% of total stake. In this study, we analyzed how this network delay and balance attack could affect the proof-of-stake consensus protocol in order to find a way for an adversary to secure the longest-chain protocol at less than 50% of the total stake.
The processing of block lifecycles is essential to the efficiency of a blockchain, which consists of four steps: creation, execution, consensus, and validation. The permissionless blockchain systems typically had very limited transaction throughput because of the performance bottleneck of consensus protocols. With recent advances in consensus protocols, the execution and validation of transactions have become the new performance bottleneck. We propose a novel framework, called FastBlock, to speed up the execution and validation steps by introducing fine-grained concurrency. Our early design of FastBlock supported three key modules: (1) a symbolic execution-based analyzer that automatically identifies minimal atomic sections in each transaction; (2) a concurrent execution step that executes possibly conflicting transactions in parallel using hardware transactional memory; (3) a concurrent validation step that introduces a happen-before relation to deterministically re-execute transactions. The improved FastBlock presented in this article supports the nonce mechanism to schedule concurrent transactions from the same account. Moreover, we empirically study the impact of concurrency on Ethereum except for performance and shed light on potential optimizations of FastBlock. Finally, we implemented FastBlock and then evaluated the performance of FastBlock. Our result shows that the FastBlock outperforms state-of-art solutions significantly in performance: the execution step and validation step speed up to 3.0x and 2.3x on average over the original serial model, respectively, with eight concurrent threads. In addition, we evaluated the impact of the nonce mechanism, and the result shows that the performance loss caused by this mechanism is acceptable in practice.
This paper presents MindTheDApp, a toolchain designed specifically for the structural analysis of Ethereum-based Decentralized Applications (DApps), with a distinct focus on a complex network-driven approach. Unlike existing tools, our toolchain combines the power of ANTLR4 and Abstract Syntax Tree (AST) traversal techniques to transform the architecture and interactions within smart contracts into a specialized bipartite graph. This enables advanced network analytics to highlight operational efficiencies within the DApp's architecture. The bipartite graph generated by the proposed tool comprises two sets of nodes: one representing smart contracts, interfaces, and libraries, and the other including functions, events, and modifiers. Edges in the graph connect functions to smart contracts they interact with, offering a granular view of interdependencies and execution flow within the DApp. This network-centric approach allows researchers and practitioners to apply complex network theory in understanding the robustness, adaptability, and intricacies of decentralized systems. Our work contributes to the enhancement of security in smart contracts by allowing the visualisation of the network, and it provides a deep understanding of the architecture and operational logic within DApps. Given the growing importance of smart contracts in the blockchain ecosystem and the emerging application of complex network theory in technology, our toolchain offers a timely contribution to both academic research and practical applications in the field of blockchain technology.