In the Bitcoin system, transaction history of an address can be useful in many scenarios, such as the balance calculation and behavior analysis. However, it is non-trivial for a common user who runs a light node to fetch historical transactions, since it only stores headers without any transaction details. It usually has to request a full node who stores the complete data. Validation of these query results is critical and mainly involves two aspects: correctness and completeness. The former can be implemented via Merkle branch easily, while the latter is quite difficult in the Bitcoin protocol. To enable the completeness validation, a strawman design is proposed, which simply includes the BF (Bloom filter) in the headers. However, since the size of BF is about KB, light nodes in the strawman will suffer from the incremental storage burden. What's worse, an integrated block must be transmitted when BF cannot work, resulting in large network overhead. In this paper, we propose LVQ, the first lightweight verifiable query approach that reduces the storage requirement and network overhead at the same time. To be specific, by only storing the hash of BF in headers, LVQ keeps data stored by light nodes being little. Besides, LVQ introduces a novel BMT (BF integrated Merkle Tree) structure for lightweight query, which can eliminate the communication costs of query results by merging the multiple successive BFs. Furthermore, when BF cannot work, a lightweight proof by SMT (Sorted Merkle Tree) is exploited to further reduce the network overhead. The security analysis confirms LVQ's ability to enable both correctness and completeness validation. In addition, the experimental results demonstrate its lightweight.
Bitcoin's throughput is far lower than those of centralized systems such as Visa and PayPal. To handle a comparable number of transactions, Bitcoin's throughput must be improved, which will require a reduction in the block propagation time. Relay networks have attracted attention as a method to improve throughput. However, the nature and strength of the effects of relay networks are not yet clear. In particular, the effects on individual nodes have received little attention. Thus, this study aims to investigate the effects of relay networks on the Bitcoin network and its nodes under the current network state in approximately 2019. We simulate a relay network under the current network state because simulation is virtually the only way to obtain data for all nodes. A major contribution of this study is that it is the first to investigate the relay network effect on the 90th percentile of block propagation time. Moreover, this study shows that relay networks benefit not only the system but also the nodes utilizing them. The utilizing nodes' blocks were more than six times more likely to be approved as valid blocks when nonutilizing and utilizing nodes generated blocks simultaneously. This finding can motivate the use of nodes in relay networks.
2 source records
Blockchain Technology Applications and Security
Caching and Content Delivery
Advanced Steganography and Watermarking Techniques
Christos Profentzas, Magnus Almgren, Olaf Landsiedel
With the rise of the Internet of Things (IoT), billions of devices ranging from simple sensors to smart-phones will participate in billions of micropayments. However, current centralized solutions are unable to handle a massive number of micropayments from untrusted devices. Blockchains are promising technologies suitable for solving some of these challenges. Particularly, permissionless blockchains such as Ethereum and Bitcoin have drawn the attention of the research community. However, the increasingly large-scale deployments of blockchain reveal some of their scalability limitations. Prominent proposals to scale the payment system include off-chain protocols such as payment channels. However, the leading proposals assume powerful nodes with an always-on connection and frequent synchronization. These assumptions require in practice significant communication, memory, and computation capacity, whereas IoT devices face substantial constraints in these areas. Existing approaches also do not capture the logic and process of IoT, where applications need to process locally collected sensor data to allow for full use of IoT micro-payments. In this paper, we present TinyEVM, a novel system to generate and execute off-chain smart contracts based on sensor data. TinyEVM's goal is to enable IoT devices to perform micro-payments and, at the same time, address the device constraints. We investigate the trade-offs of executing smart contracts on low-power IoT devices using TinyEVM. We test our system with 7,000 publicly verified smart contracts, where TinyEVM achieves to deploy 93% of them without any modification. Finally, we evaluate the execution of off-chain smart contracts in terms of run-time performance, energy, and memory requirements on IoT devices. Notably, we find that low-power devices can deploy a smart contract in 215 ms on average, and they can complete an off-chain payment in 584 ms on average.
Philipp Frauenthaler, Marten Sigwart, Christof Spanring, Michael Sober · 5 authors
Current blockchain relay schemes require the immediate validation of each relayed block header by the destination blockchain. This leads to high operating cost when deploying these relays between Ethereum-based blockchains where validating block headers on-chain is computationally expensive.To overcome these limitations, we introduce a novel relay scheme that employs a validation-on-demand pattern combined with economic incentives to reduce the cost of operating a relay between Ethereum-based blockchains by up to 92%. With this relay scheme, decentralized interoperability between blockchains like Ethereum and Ethereum Classic becomes feasible.
A popular method in practice offloads computation and storage in blockchains by relying on committing only hashes of off-chain data into the blockchain. This mechanism is acknowledged to be vulnerable to a stalling attack: the blocks corresponding to the committed hashes may be unavailable at any honest node. The straightforward solution of broadcasting all blocks to the entire network sidesteps this data availability attack, but it is not scalable. In this paper, we propose ACeD, a scalable solution to this data availability problem with $O(1)$ communication efficiency, the first to the best of our knowledge. The key innovation is a new protocol that requires each of the $N$ nodes to receive only $O(1/N)$ of the block, such that the data is guaranteed to be available in a distributed manner in the network. Our solution creatively integrates coding-theoretic designs inside of Merkle tree commitments to guarantee efficient and tamper-proof reconstruction; this solution is distinct from Asynchronous Verifiable Information Dispersal (in guaranteeing efficient proofs of malformed coding) and Coded Merkle Tree (which only provides guarantees for random corruption as opposed to our guarantees for worst-case corruption). We implement ACeD with full functionality in 6000 lines of Rust code, integrate the functionality as a smart contract into Ethereum via a high-performance implementation demonstrating up to 10,000 transactions per second in throughput and 6000x reduction in gas cost on the Ethereum testnet Kovan.
Most storage systems adopt distributed architecture to reach high reliability. In these distributed systems, a well-balanced data distribution can improve storage reliability. However, existing schemes rely on dealers to distribute data, bring back the risk of single-point failure again. In this paper, we propose a blockchain-based storage system with financial incentives for load-balancing. Nodes in the system are rational and compete for data to earn a reward. The only source of storage rewards is from users' payment for leasing storage. To reach load-balancing, we design a new incentive scheme, which contains an income function to reward the nodes who own proper data and punish the nodes who own excessive data. In the system, each node continuously generates a proof of storage. We present a chain structure using the proofs to detect node failures and record data distribution. The state of distribution could be taken as input to the income function for reward allocation. We decouple the role of nodes from miners to reduce their workload, making the system more compatible. Our simulation experiments show efficient performance in the data distribution. The system can always recover to a balanced status as the blockchain grows up.
The Bitcoin P2P network is at the core of all communications between clients. The reachable part of this network has been explored and analyzed by numerous studies. Unreachable nodes, however, are, in most part, overlooked. Nonetheless, they are a relevant part of the network and play an essential role in the propagation of messages. In this paper, we focus on transaction propagation and show that increasing the participation of unreachable nodes can potentially improve the robustness and efficiency of the network. In order to do that, we propose a few changes to the network protocol. Additionally, we design a novel transaction propagation protocol that explicitly involves unreachable nodes to provide better protection against deanonymization attacks. Our solutions are simple to implement and can effectively bring immediate benefits to the Bitcoin network.
Institut Teknologi Sepuluh Nopember, Yunifa Miftachul Arif, Hani Nurhayati, Universitas Islam Negeri Maulana Malik Ibrahim · 10 authors
One thing that tourists need to plan their tourism activities is a recommendation system. The tourism destinations recommendation system in this study has three primary nodes, namely user, server, and sensor. Each node requires the ability to share data to produce recommendations that the user expects through their mobile devices. In this paper, we propose the data-sharing system scheme uses a blockchain-based decentralized network that each node can be connected directly to each other, to support the exchange of data between them. The block architecture used in the blockchain network has three main parts, namely block information, hashes, and data. Each type of node has a different structure and direction of data communication. Where the user node sends destination assessment data to the server node, then the server node sends data from the machine learning process to the user node. The sensor sends dynamic data about popularity, traffic, and weather to the user node as consideration for finalizing the generating recommendations process. In the process of sending data, each node in the blockchain network goes through several functions, including hashing, block validation, chaining block, and broadcast. We conduct web-based experiments and analysis of the data-sharing system to illustrate the system works. The experimental results show that the system handles data circulation with an average time of mine is 84.5 ms in sending multi-criteria assessment data from the user and 119.1 ms in sending data of machine learning result from the server.
Sharing energy storage (SES) is a novel business model in order to increase the profits and improve the utilization rate of idle energy storage facilities. On the other hand, blockchains can be competently applied in the transaction and operation of SES because of distributed network architecture, traceability and tamper proof. In this paper, a management model of SES based on proxy signatures in the blockchain environment is proposed. Many management models including the principal-agent model are analyzed for SES in terms of benefit, cost, resources, and so on. Moreover, a blockchain framework and a typical transaction process of SES is presented. Finally, a proxy signature mechanism based on the ElGamal algorithm is proposed in order to address the problem that the signature power of nodes cannot be transferred on blockchains. Simulation results show that the proposed proxy signature mechanism can achieve the delegation of digital signature power under the premise of security and reliability, which is suitable for the management model of SES on blockchains.
Vehicular ad hoc networks (VANETs) are projected to be an integral component in intelligent transportation systems, poised to support road safety services via the Vehicle to Vehicle (V2V) and Vehicle to Roadside (V2R) units communication. With the evolution of technology and the growth in the number of smart vehicles, traditional VANETs face technical challenges in deployment and management due to less scalability and poor connectivity. Current smart vehicles are identified, authenticated, and connected through central cloud servers. This model will have limited scalability as the technology becomes pervasive, and the cloud servers will remain a single point of failure that can disrupt the entire network. Therefore, we need a secure distributed system to reduce the network traffic rate. In this paper, we propose a blockchain-based distributed message exchange system that will handle the exchange of safety and periodic beacon messages among vehicles. Since blockchain is characterized as being a decentralized and non-tampering system. We considered saving the safety messages only in the blockchain as they occur less than the periodic messages and they are more important. We propose to implement the blockchain per country to reduce the number of nodes/vehicles joining the network. We also reduce the block body size by using the Kademlia Distributed Hash Table (DHT) to broadcast the beacon messages. Experimental evaluation shows that the system can protect a V2V network against different attack types, such as sybil attack and alteration attack with TPR more than 95%. The experiments also show that the block body size is reduced by a factor of 1:5, which helps in broadcasting the data faster.
The Blockchain is a new technology developed on the basis of Bitcoin system. In fact, the developing blockchain technology has been going beyond the single application scope of cryptocurrency, and becoming one of a core support to solve financial, economic and even social problems on Internet. Based on the Bitcoin system, this paper first analyzes the basic issues of implementing distributed storage, consensus negotiation and cryptographic security in the blockchain. On this basis, several representative blockchain technologies are analyzed, including Smart-contracts, Super-ledger and Stable-currency system. Finally, the trend of his applications are prospected.
Blockchain technologies have given lots of impact on the existing market trends during the past few years. In particular, smart contract mechanism based on blockchain can guarantee the automatic and secure trading. In this paper, we propose a novel approach for blockchain-based data marketplace system. It can facilitate effective data retrieval and automatic transactions between various data providers and consumers. Also, we provide the named and secure data communication at the network layer, based on NDN. We present the system architecture and describe the service flows that show functionality of the marketplace.
David Cordova Morales, Alexandre Laubé, Thi Mai Trang Nguyen, Guy Pujolle
Blockchain is one of the most prominent emerging technologies. It offers the ability to maintain an anti-tamper distributed database, ensuring the integrity and authenticity of data in a decentralized system. However, when using blockchain in a dynamic community, such as mobile nodes in an ad hoc and mesh networks, the chain structure is no longer enough to deal with node mobility. In this paper, we address the challenges of using a DAG-based blockchain for mobile and ad hoc networks (MANETs) that we call “blockgraph”. We define the characteristics of the blockgraph framework. This includes: the requirement needed for a consensus protocol in order to be resilient to network partitions; the specifications of the blockgraph protocol that ensure the maintenance of the blockgraph data structure; and a group management system that reacts to network topology changes that provide with relevant network topology information to the blockgraph framework. Finally, we implemented our framework in the discrete event network simulator NS3 as a proof-of-concept for our blockgraph.
We present a blockchain radio access network (B-RAN) as an advanced wireless access paradigm. The proposed B-RAN unites massive trustless subnetworks to form a large-scale trustworthy cooperative network by leveraging the blockchain principle. We introduce the economic concept of network effects with respect to the benefit of a growing B-RAN. We show that B-RAN can create and capture values by connecting multilateral groups and constructing a multi-sided platform (MSP). To establish multi-fold trust among distinct groups for deep integrations and healthy interactions, we divide functions of B-RAN into six layers within a hierarchical architecture to build trust from the ground up, and provide a number of key enabling technologies to overcome major obstacles in B-RAN. More importantly, we assess the performance of B-RAN using our unique in-house prototype through three representative case studies.
Superlight clients enable the verification of proof-of-work-based blockchains by checking only a small representative number of block headers instead of all the block headers as done in simplified payment verification (SPV). Such clients can be embedded within other blockchains by implementing them as smart contracts, allowing for cross-chain verification. One such interesting instance is the consumption of Bitcoin data within Ethereum by implementing a Bitcoin superlight client in Solidity. While such theoretical constructions have demonstrated security and efficiency in theory, no practical implementation exists. In this work, we put forth the first practical Solidity implementation of a superlight client which implements the NIPoPoW superblocks protocol. Contrary to previous work, our Solidity smart contract achieves sufficient gas-efficiency to allow a proof and counter-proof to fit within the gas limit of a block, making it practical. We provide extensive experimental measurements for gas consumption. The optimizations that enable gas-efficiency heavily leverage a novel technique which we term hash-and-resubmit, which almost completely eliminates persistent storage requirements, the most expensive operation of smart contracts in terms of gas. Instead, the contract asks contesters to resubmit data and checks their veracity by hashing it. Other optimizations include off-chain manipulation of proofs in order to remove expensive look-up structures, and the usage of an optimistic schema. We show that such techniques can be used to bring down gas costs significantly and may be of independent interest. Lastly, our implementation allows us to calculate concrete cryptoeconomic parameters for the superblocks NIPoPoWs protocol and in particular to make recommendations about the monetary value of the collateral parameters. We provide such parameter recommendations over a variety of liveness settings.
Crowdsourcing can improve productivity by distributing tasks to the public. However, the traditional crowd-sourcing system has some problems. We have implemented a novel crowdsourcing system based on blockchain, which can solve the single point of failure. considering the risk of data loss in a centralized system, we complete data storage based on ipfs and propose a data access control method for ipfs. When disputes occurred during the crowdsourcing process, the traditional method was to decide results by the centralized platform, which may lead to unfairness. We innovatively apply the quadratic voting to the crowdsourcing system. And for the sybil attack in the voting, the process of voting was improved. The experimental results prove the feasibility of the crowdsourcing system.
State sharding is a common solution to the scalability problem in blockchain systems, allowing nodes to hold a partial view of the system state. With sharding, the processing of a transaction might not be completed locally within a node and potentially requires involvement of multiple shards. Such cross-shards transactions have a negative impact on system performance and are frequent with traditional state partition solutions which are often based on a simple mapping of data into shards. By locating together parts of the system state accessed by frequent transactions, the amount of cross-shard transactions can be reduced. On the other hand, the representation of such particular mappings can be memory intensive. In this article, we study traffic-aware sharding that can be described in memory-efficient mappings. We first survey existing mapping schemes in common blockchains. We indicate the tradeoff between the size of the mapping of data to shards and the required transaction processing time and suggest algorithms for finding memory-light sharding of low cross-shard rate. We generalize the approach towards an efficient incremental computation of shards and probabilistic representation of the mapping to shards. We examine the efficiency of the solutions and the required frequency of sharding computation based on real information of the Ethereum network.
Lam Duc Nguyen, Israel Leyva‐Mayorga, Amari N. Lewis, Petar Popovski
Mobile devices with embedded sensors for data collection and environmental sensing create a basis for a cost-effective approach for data trading. For example, these data can be related to pollution and gas emissions, which can be used to check the compliance with national and international regulations. The current approach for IoT data trading relies on a centralized third-party entity to negotiate between data consumers and data providers, which is inefficient and insecure on a large scale. In comparison, a decentralized approach based on distributed ledger technologies (DLT) enables data trading while ensuring trust, security, and privacy. However, due to the lack of understanding of the communication efficiency between sellers and buyers, there is still a significant gap in benchmarking the data trading protocols in IoT environments. Motivated by this knowledge gap, we introduce a model for DLT-based IoT data trading over the Narrowband Internet of Things (NB-IoT) system, intended to support massive environmental sensing. We characterize the communication efficiency of three basic DLT-based IoT data trading protocols via NB-IoT connectivity in terms of latency and energy consumption. The model and analyses of these protocols provide a benchmark for IoT data trading applications.
In this paper, we propose a scheme called securePrune for reducing the storage space of a full node and synchronization time of bootstrapping nodes joining the Peer-to-Peer (P2P) network in an Unspent Transaction Outputs (UTXO) based blockchain like bitcoin using RSA accumulators. The size of the bitcoin blockchain is growing linearly with transactions. We propose a new block structure to represent the state of a blockchain also called UTXO set by including an accumulator of a state in the block header and proofs of knowledge for inclusion and deletion of the transactions of the current block in the block. In our scheme, the miners periodically release a snapshot of the blockchain state. The other full nodes in the network, securely prune the historical blocks after attaining the required number of confirmations for the snapshot block, which in turn confirms the snapshot of the state through an accumulator specified in the block header and proofs inside the block. The secure and periodic pruning of the old blocks, reduce the synchronization time for a new node joining into the network. The simulation results demonstrate a significant reduction in the storage space of a full node and bootstrapping cost of the new nodes.
The success of Bitcoin and Ethereum has attracted many efforts to build high-throughput blockchain systems. This paper focuses on transaction dissemination --- a rather overlooked issue in these systems. We argue that efficient transaction dissemination is the key for a blockchain system to sustain at high-throughput --- usually thousands of transactions per second --- and the existing solutions fell short at doing so.
It is widely accepted that Ethereum mining is highly centralized.\nNonetheless, centralization has been mostly characterized by exclusively\nlooking at the influence that independent miners or mining pools can have over\nthe network. Moreover, models of mining behavior assume that miners are either\nunrelated or only relate via mining pools under highly structured and\ntransparent agreements. If these assumptions and the predictions they entail\nwere to be completely accurate, there would not be any evidence of on-chain\ntransactions between miners, other than the ones expected from mining pool\npayouts. By looking at on-chain transactions between miners in the Ethereum\nNetwork we find that aside from the payouts from mining pools to small miners,\nthere are also transactions that define relationships between mining pools,\nindependent miners and between independent miners and mining pools.\nFurthermore, by characterizing the topology of the network of miner\ntransactions, we find the emergence of highly connected clusters that control\nsignificant amounts of hashing power and exhibit relationships in the opposite\ndirection of what theoretical models predict. This more nuanced\ncharacterization of mining centralization can help identify network\nvulnerabilities and inform protocol redesigns.\n
This research is dedicated to the development of a prototype of open infrastructure for users' internet traffic filtering on a browser level. We described the advantages of a distributed approach in comparison with current centralized solutions. Besides, we suggested a solution to define the optimum size for a URL storage block in Ethereum network. This solution may be used for the development of infrastructure of DApps applications on Ethereum network in future. The efficiency of the suggested approach is supported by several experiments.