Random number generators (RNG) are an underlying part of Proof-of-Stake consensus protocols and are critically important for many distributed applications on blockchains and directed acyclic graphs (DAGs). A fault-tolerant approach needs the communication and computation synchronicity assumptions to resolve it. The authors present DisCO-an upgraded version of the No-Dealer algorithm. DisCO works under the partial synchronous assumption and guarantees output per run, compared to No-Dealer, which works in a synchronous model and either generates output or detects a faulty participant. DisCO's communication model is more practical than NoDealer's as it meets the Internet. We implemented DisCO as a decentralized application on Hedera Hashgraph DAG. The source code and performance tests are provided.
Akshay M. Fajge, Siddharth Thakur, Rahul Kumar, Raju Halder
With the advancement of blockchain technology at a breakneck pace, numerous organizations are now experimenting with blockchain solutions for their operations. In this nascent stage, due to the scarcity of blockchain domain experts, there is a growing trend towards an automated conversion of legacy systems to blockchain-based systems. To this aim, this paper presents an automated framework that facilitates the migration of centralized Java-based applications to decentralized Solidity-based Ethereum applications. The experimental results are encouraging, demonstrating its ability to handle large-scale Java codebase. To the best of our knowledge, this is the first proposal of its kind that enables the translation of Java source codes to Solidity source codes.
Sebastian Müller, Angelo Capossele, Bartosz Kuśmierz, Vivian Lin · 9 authors
The security of any Distributed Ledger Technology (DLT) depends on the safety of the network layer. Much effort has been put into understanding the consensus layer of DLTs. However, many network layer designs seem ad-hoc and lack a careful analysis of the influence of the design decisions on the whole DLT system. We propose a salt-based automated neighbor selection protocol that shows the inherent tradeoffs of certain design decisions and allows a quantitative treatment of some network topology requirements. This example may serve as a design framework and facilitate future research. We provide a selection of results from simulations to highlight some tradeoffs in the design decisions.
The Bitcoin peer-to-peer network ensures the consensus between the different nodes responsible for the propagation of the blocks containing the validated bitcoin transactions. The quality and safety of this network are therefore particularly essential. In this work, we present a study of the public nodes that form the backbone of the Bitcoin p2p network. We analyze the results of our measurement campaign that was made following a well-defined and reproducible methodology. In particular we analyze several criteria that can affect the network resilience: distribution and security assessment of the clients' versions, churn, detection of Sybil nodes, dynamicity and popularity of peers. We also investigate the countermeasures deployed to prevent an accurate inference of the network topology and show their effectiveness.
Peer to Peer (P2P) energy trading were introduced to store, manage, share, track, and access the permanently stored energy data. In particular traditional energy trading systems provide a centralized approach and connectivity among the different participating trusted users. Recently Blockchain Technology shows a potential solution to address critical challenges such as gapped communications, security in an untrusted decentralized environment, inefficient transactions retrieval (low throughput, high latency, high CPU and memory utilization, etc.), and scattered energy records. In this paper a framework is proposed, to record the energy transactions, a JavaScript-based smart contract is deployed over the Hyperledger Sawtooth Proof of Elapsed Time (PoET). Additionally, the proposed framework is shown as a working prototype, and the performances are evaluated taking transaction per second, read and write latency, read write throughput, the number of successful and failed transactions, CPU utilization, network traffic input, and output. Also, it is shown that PoET's performance is better than PoW for multi-hosting environments. It has been observed that out of 1000 transactions sent for each round by clients through Hyperledger Caliper and REST API services, PoET could able to perform 946 transactions successfully, whereas PoW completed only 627 transactions. The results obtained in various rounds of evaluation affirm the superiority of the framework.
Mihai Christodorescu, Erin English, Wanyun Catherine Gu, David Kreissman · 10 authors
With the innovation of distributed ledger technology (DLT), often known as\nblockchain technology, there has been significant growth of digital tokens in\nthe form of cryptocurrencies, stablecoins, and central bank digital currencies.\nAs the number of DLT networks increases, each with varying design\ncharacteristics, the likelihood that transacting parties are on the same\nnetwork decreases. Thus, it is crucial to facilitate payments that are\nuniversal across networks, scalable to massive loads, and highly available. We\nenvision a future payment network that may be built on top of DLT networks\nwithout being subject to their limitations on interoperability, scalability,\nand availability faced by DLT payment solutions today. Specifically, we propose\na hub-and-spoke payment route, referred to here as Universal Payment Channels\n(UPC), that can be used to support digital token transfers of funds across\ndifferent networks through payment channels. We further discuss the potential\nuse cases of the UPC technology to support, and not complicate, an already\nrobust digital payment ecosystem. Finally, through the paper, we share some\nfuture directions of the UPC technology.\n
In this paper we describe LUNES-Blockchain, an agent-based simulator of blockchains that relies on Parallel and Distributed Simulation (PADS) techniques to obtain high scalability. The software is organized as a multi-level simulator that permits to simulate a virtual environment, made of many nodes running the protocol of a specific Distributed Ledger Technology (DLT), such as the Bitcoin or the Ethereum blockchains. This virtual environment is executed on top of a lower-level Peer-to-Peer (P2P) network overlay, which can be structured based on different topologies and with a given number of nodes and edges. Functionalities at different levels of abstraction are managed separately, by different software modules and with different time granularity. This allows for accurate simulations, where (and when) it is needed, and enhances the simulation performance. Using LUNES-Blockchain, it is possible to simulate different types of attacks on the DLT. In this paper, we specifically focus on the P2P layer, considering the selfish mining, the 51% attack and the Sybil attack. For which concerns selfish mining and the 51% attack, our aim is to understand how much the hash-rate (i.e. a general measure of the processing power in the blockchain network) of the attacker can influence the outcome of the misbehaviour. On the other hand, in the filtering denial of service (i.e. Sybil Attack), we investigate which dissemination protocol in the underlying P2P network makes the system more resilient to a varying number of nodes that drop the messages. The results confirm the viability of the simulation-based techniques for the investigation of security aspects of DLTs.
Christos Chrysoulas, A. M. Thomson, Nikolaos Pitropakis, Pavlos Papadopoulos · 10 authors
The continuously advancing digitization has provided answers to the bureaucratic problems faced by eGovernance services. This innovation led them to an era of automation it has broadened the attack surface and made them a popular target for cyber attacks. eGovernance services utilize internet, which is currently a location addressed system where whoever controls the location controls not only the content itself, but the integrity of that content, and the access to that content. We propose GLASS, a decentralised solution which combines the InterPlanetary File System (IPFS) with Distributed Ledger technology and Smart Contracts to secure EGovernance services. We also create a testbed environment where we measure the IPFS performance.
In this paper we describe LUNES-Blockchain, an agent-based simulator of\nblockchains that relies on Parallel and Distributed Simulation (PADS)\ntechniques to obtain high scalability. The software is organized as a\nmulti-level simulator that permits to simulate a virtual environment, made of\nmany nodes running the protocol of a specific Distributed Ledger Technology\n(DLT), such as the Bitcoin or the Ethereum blockchains. This virtual\nenvironment is executed on top of a lower-level Peer-to-Peer (P2P) network\noverlay, which can be structured based on different topologies and with a given\nnumber of nodes and edges. Functionalities at different levels of abstraction\nare managed separately, by different software modules and with different time\ngranularity. This allows for accurate simulations, where (and when) it is\nneeded, and enhances the simulation performance. Using LUNES-Blockchain, it is\npossible to simulate different types of attacks on the DLT. In this paper, we\nspecifically focus on the P2P layer, considering the selfish mining, the 51%\nattack and the Sybil attack. For which concerns selfish mining and the 51%\nattack, our aim is to understand how much the hash-rate (i.e. a general measure\nof the processing power in the blockchain network) of the attacker can\ninfluence the outcome of the misbehaviour. On the other hand, in the filtering\ndenial of service (i.e. Sybil Attack), we investigate which dissemination\nprotocol in the underlying P2P network makes the system more resilient to a\nvarying number of nodes that drop the messages. The results confirm the\nviability of the simulation-based techniques for the investigation of security\naspects of DLTs.\n
Decentralized control, low-complexity, flexible and efficient communications are the requirements of an architecture that aims to scale blockchains beyond the current state. Such properties are attainable by reducing ledger size and providing parallel operations in the blockchain. Sharding is one of the approaches that lower the burden of the nodes and enhance performance. However, the current solutions lack the features for resolving concurrency during cross-shard communications. With multiple participants belonging to different shards, handling concurrent operations is essential for optimal sharding. This issue becomes prominent due to the lack of architectural support and requires additional consensus for cross-shard communications. Relying on the advantages of hybrid Proof-of-Work/Proof-of-Stake (PoW/PoS), like Ethereum , hybrid consensus and 2-hop blockchain , we propose Reinshard , a new blockchain that inherits the properties of hybrid consensus for optimal sharding. Reinshard uses PoW and PoS chain-pairs with PoS sub-chains for all the valid chain-pairs where the hybrid consensus is attained through Verifiable Delay Function (VDF). Our architecture provides a secure method of arranging nodes in shards and resolves concurrency conflicts using the delay factor of VDF. The applicability of Reinshard is demonstrated through security and experimental evaluations. A practical concurrency problem is considered to show the efficacy of Reinshard in providing optimal sharding.
Soo Hoon Maeng, Meryam Essaid, Sejin Park, Hongtaek Ju
The Ethereum network uses Kademlia, a well-known P2P network, which allows the search for new nodes, and the change of connection with neighboring nodes. The Ethereum network must cope with security attacks such as DDoS attacks, 51% attacks, and Sybil attacks, and scalability issues, which slows down the transaction processing speed per second (TPS) as the network expands. A deep analysis of the dynamically changing topology and the connection between the nodes constituting the topology is needed to solve these problems. Therefore, in this paper, we measure the topology in the Ethereum network using a passive probing data collection to search for active nodes in the network and an active probing method to check the activity of nodes participating in the Ethereum network. Our results give a clear insight into the topology properties and topology visualization.
In recent years, research has shown the networking layer’s significant influence on the scalability, security, and privacy of blockchain systems. Such large-scale networks however exhibit a degree of complexity that demands model-based simulations as real-world experiments are often not possible. In this work, we methodically characterize blockchain networks by reference to the paradigmatic Bitcoin peer-to-peer network, explore the state-of-the-art protocols, and emphasize this key design space. To this end, we conducted a longitudinal measurement study on the Bitcoin network, from which we extract a comprehensive network model and implement it as part of the bns network simulation framework. We validate the model in comparison to real-world measurements as well as to results from related work. Moreover, we experimentally show how network utilization and miners’ geographical location impact the block propagation characteristics.
High-Definition (HD) map service requires more frequent update and much larger data volume than traditional map services, so that it is very difficult to handle HD map update by existing offline data collection such as survey fleets, and centralized cloud-based map services. To solve this problem, vehicle crowd-sourcing and edge computing infrastructure are proposed to timely capture the change of the physical world and distributedly process the huge amount of raw data close to the vehicles. In such a decentralized environment, Distributed Ledger Technology (DLT), such as blockchain, is very promising to meet some of the important requirements of data integrity and traceability of map update, but it is challenging to meet the requirement of frequent map update and scale to a large-scale system. In this work, we propose a salable HD map update management system by leveraging multiple blockchain networks in parallel and dynamically assign the generated map update to the corresponding blockchains according to the location and update frequency requirements. To verify the proposed system, we prototyped it based on the Hyperledger Fabric, an open-source implementation of consortium blockchain, and tested it in the lab environment.
Abstract The Bitcoin P2P network currently represents a reference benchmark for modern cryptocurrencies. Its underlying protocol defines how transactions and blocks are distributed through all participating nodes. To protect user privacy, the identity of the node originating a message is kept hidden. However, an adversary observing the whole network can analyze the spread pattern of a transaction to trace it back to its source. This is possible thanks to the so-called rumor centrality , which is caused by the symmetry in the spreading of gossip -like protocols. Recent works try to address this issue by breaking the symmetry of the Diffusion protocol, currently used in Bitcoin, and leveraging proxied broadcast. Nonetheless, the complexity of their design can be a barrier to their adoption in real life. In this work, we propose Clover, a novel transaction relay protocol that protects the source of transaction messages with a simple, yet effective, design. Compared to previous solutions, our protocol does not require building propagation graphs, and reduces the ability of the adversary to gain precision by opening multiple connections towards the same node. Experimental results show that the deanonymization accuracy of an eavesdropper adversary against Clover is up to 10 times smaller compared to Diffusion.
With the recent rise in the cost of transactions on blockchain platforms, there is a need to explore other service models that may provide a more predictable cost to customers and end-users. We discuss the Contract Service Provider (CSP) model as a counterpart of the successful Internet Service Provider (ISP) model. Similar to the ISP business model based on peered routing-networks, the CSP business model is based on multiple CSP entities forming a CSP Community or group offering a contract service for specific types of virtual assets. We discuss the contract domain construct which encapsulates well-defined smart contract primitives, policies and contract-ledger. We offer a number of design principles borrowed from the design principles of the Internet architecture.
This paper presents a simple and self-adjusting blockchain protocol called ORIC to make full use of the available bandwidth as far as possible. ORIC follows the Nakamoto protocol and allows many more blocks to be produced during the block-time so that the bandwidth can be exploited to its maximum extent. Recorded blocks are organized into a Directed Acyclic Graph(DAG) sequence from which a transaction total order can be deterministically derived as the blockchain ledger. We give a theoretical analysis of ORIC’s properties, such as security and liveness, and evaluate its performance on a distributed system simulator with 1000 full nodes designed. The simulation shows that ORIC can achieve bandwidth utilization close to 50% while confirming transactions in 5-7 minutes under the bandwidth of 20Mbps available. More importantly, our protocol can achieve an optimal throughput by a self-adjusting mechanism when the available bandwidth changes in a peer-to-peer network while hardly affecting security.
Samuel H. Christie, Amit K. Chopra, Munindar P. Singh
A decentralized application involves multiple autonomous principals, e.g., humans and organizations. Autonomy motivates (i) specifying a decentralized application via a protocol that captures the interactions between the principals, and (ii) a programming model that enables each principal to independently (from other principals) construct its own protocol-compliant agent. An agent encodes its principal's decision making and represents it in the application. We contribute Deserv, the first protocol-based programming model for decentralized applications that is suited to the cloud. Specifically, Deserv demonstrates how to leverage function-as-a-service (FaaS), a popular serverless programming model, to implement agents. A notable feature of Deserv is the use declarative protocols to specify interactions. Declarative protocols support implementing stateful agents in a manner that naturally exploits the concurrency and autoscaling benefits offered by serverless computing.
Ethereum is the second-largest cryptocurrency, which is an open-source public blockchain platform with smart contract functionality. With the increasing popularity of Ethereum, considerable attention has been paid to its privacy and anonymity. Previous work in Ethereum deanonymization mostly focused on the analysis of its transaction graph and user behaviors. In this paper, for the first time we explored the feasibility of deanonymizing Ethereum users based on P2P network analysis. By measurement and analysis, we observed that the attacker can make connections with approximately 90% mainnet synced full nodes. Based on the well-connected supernode, the deanonymization experiments with basic estimators preliminarily indicate that the anonymity of Ethereum P2P network is pretty limited. To further improve the effect of deanonymization, we implemented and evaluated a machine learning based estimator, which reduces the influence of network delay on deanonymization and thus increases the success rate to 88%. At last, we provide the discussion about the anonymity and efficiency of the propagation mechanisms.
The growing web of data warrants better data management strategies. Data silos are single points of failure and they face availability problems which lead to broken links. Furthermore the dynamic nature of some datasets increases the need for a versioning scheme. In this work, we propose a novel architecture for a linked open data infrastructure, built on open decentralized technologies. IPFS is used for storage and retrieval of data, and the public Ethereum blockchain is used for naming, versioning and storing metadata of datasets. We furthermore exploit two mechanisms for maintaining a collection of relevant, high-quality datasets in a distributed manner in which participants are incentivized. The platform is shown to have a low barrier to entry and censorship-resistance. It benefits from the fault-tolerance of its underlying technologies. Furthermore, we validate the approach by implementing our solution.
Caciano dos Santos Machado, Renan R. S. dos Santos, Carla Merkle Westphall
Community networks are prone to free-riders, i.e., participants who take advantage of cooperation from others' routers but do not contribute reciprocally. In this paper, we present HARPIA, a system for credit-based incentive mechanisms for data forwarding in community networks aimed to prevent selfish behavior. HARPIA does not require a trusted third-party or tamper-resistant security modules as in other incentive mechanisms. Instead, it uses a distributed accounting scheme (DPIFA) to estimate the balance of data forwarding contribution and consumption of each network router and settle correspondent cryptocurrency debts on an Ethereum smart contract. On-chain settlement transactions are performed every HARPIA cycle (e.g., daily, weekly, monthly) and must be validated by at least m-of-n network routers using a multi-signature scheme (MuSig). We also realized a performance evaluation, security threat assessment, and cryptocurrency costs estimation. Results show that our proposal is suitable for community networks with up to 64 infrastructure routers under specific m-of-n MuSig thresholds.