A novel double spending attack countermeasure in blockchain

The paper investigates the probability of one of the most famous attacks - double spending attacks on the blockchain system, which are based on consensus mechanisms based on the proof of the work done using hash functions. Unlike previously known works describing the analytical expression for the probability of success of a double-spend attack, this paper proposes a model of independent players that is different from existing models. In our opinion, this model more adequately describes the processes that occur during the formation of a chain of blocks, but leads to other quantitative results. An expression is given that characterizes the probability of an attacker conducting a successful double-spend attack on a blockchain system depending on the number of confirmations used, as well as the hashrate by an honest network and the attacker. Quantitative results are presented, as well as a comparison of the results obtained with the most famous works in this area. Based on the results obtained, recommendations are given for determining the “safe” number of confirmations for successfully resisting a double spending attack on the blockchain system.

To build safe and reliable distributed decentralized systems using blockchain technology, a continuous chain of blocks is created, the unauthorized modification of which is not allowed by the applied cryptographic mechanisms. This is achieved by using unidirectional, collision resistant and search prototypes of cryptographic functions whose hash values from previous blocks are included in subsequent blocks. As a result, an unauthorized change in at least one bit of data in the previous blocks will be immediately detected. However, in the case of distributed storage of information, there is an additional requirement of synchronization of individual chains of blocks that are stored by various nodes. These and other issues are resolved by applying consensus building mechanisms, through which, after a certain sequence of actions, a continuous sequence of blocks (blockchain chain) becomes the same on all nodes of a decentralized network. This work examines one of the main vulnerabilities of blockchain systems built by consensus with probabilistic completion, namely, a double-spend attack. Based on the model of “independent players”, an analytical expression is obtained for calculating the probability of an attacker's successful double-spending attack. The quantitative values of the probability of a successful attack are given for various abilities of an attacker, a different number of generated blocks and a different race duration. Using computer simulation, the calculated values are experimentally verified. All empirical estimates were obtained with high accuracy (relative error not higher than 1%) and reliability (confidence level of at least 99%). To confirm the adequacy of the results obtained, a comparison of empirical results with theoretical calculations is given.

SummaryThe block chain is the emerging domain that offers the features like shared, immutable, and decentralized dataset that saves the asset's history. Security and storage are the most challenging aspect. The classical techniques' issues and challenges are an encouragement for developing a fresh block chain‐assisted IPFS model with access control policies. Hence, this research paper introduces an effective access control and authentication based on an interplanetary file system (IPFS)‐based block chain and access control system for attaining secured transactions. The developed method comprises five entities, that is smart contract, data owner, data requester, block chain and IPFS along with eight phases, to be exact setup, user registration, initialization, storage and data encryption, authentication, testing, access control, and decryption phase, to provide better access control and storage capacity. The proposed IPFS‐based block chain and access control system offered effective storage and secure transactions in the block chain network. The highest detection rate (0.870), lowest communication overhead (0.766 MB), and highest privacy rate (0.719) are all achieved by the proposed IPFS‐based block chain and access control system.

Blockchain technologies have been developing very fast recently. Ethereum, as the second generation of blockchain, can support smart contracts with various functions. Blockchain, combined with IoT technologies like RFID, can bring more security into IoT systems. It has been noted that just storing hash values, addresses and transaction records cannot meet the needs of various blockchain applications. Thus, how to test capacity of reading/writing data for blockchain and further make comparisons with the traditional relational databases needs to be paid attention. Although there has been some research on testing and analyzing the performance of blockchains, few studies focus on analyzing blockchains and relational databases. This test was conducted to analyze the capacities of reading/writing data and processing/recording transactions of blockchains and relational databases. Ethereum and MySQL are chosen as the representatives of blockchain and relational databases. This test has three aims: (1) getting the detailed data of the blockchain’s capacity of processing transactions; (2) identifying the bottleneck or potential bottleneck in blockchain systems; (3) putting forward a testing method and testing indexes which are reasonable, practical and compatible with the current development situations of blockchain systems. With the results data, it was concluded that the maximum data volume in single transaction on blockchain network was about 1/10 of MySQL. As for the time spent in processing single transaction, the blockchain network was 80–2000 times as much as MySQL. Thus, it’s recommended to store little-size data into blockchain. For more detailed testing, these indexes and testing method can be referenced.

Blockchain-based applications have been recently introduced in communication networks. Different applications require different levels of service whereas existing blockchain-based applications mostly provide a single class of service. In this paper, we propose a multi-class blockchain services (MCBS) framework that prioritizes the processing of time-critical blockchain-based applications in communication networks. We model MCBS as a queueing system and derive the average service times for the different classes. We then formulate a multi-objective optimization problem to simultaneously optimize the average service time and aggregate transactions arrival rate. The numerical results show that existing blockchains may not satisfy the requirements of time-critical applications whereas a high priority queue in MCBS may meet the requirement. In addition, we analyze MCBS under double-spend attacks and show that with maximum attacker hash power, the blockchain system can still be stable if the aggregate transaction arrival rate is lower than half of its maximum achievable value.

Blockchain technology is being studied in many innovative applications, such as: cryptocurrencies, smart contracts, communication systems, healthcare, Internet of Things, financial systems, software development, electronic voting and many others. Using a transparent and fully distributed peer-to-peer blockchain architecture, applications benefit from a data-only model, in which “transactions” are accepted into the blockchain ledger and, if the system is functioning properly, cannot be modified or deleted. The transparency of blockchain systems makes it possible to store publicly available and irrefutable records. A peer-to-peer blockchain system provides verifiable ledger maintenance without centralized management, which solves the problems of a single point of failure and a single point of trust. The article deals with the issue of the security of application of accounting systems built on decentralized principles using blockchain technology. Particular attention is paid to the problem of the possibility of double spending in such accounting systems. The article exemplifies the reorganization of records in blockchain ledgers, performed by successfully carrying out a 51% attack on consensus algorithms based on proof of work. Given refinement of analytical expressions of 51% attack probability obtained in the works of S. Nakamoto and M. Rosenfeld using a more general model, namely, the model of independent players, where the probability of block formation by attackers and an honest network are independent events. The results of comparing of the success probability of a double-spending attack on the blockchain systems calculated according to different models are presented.

Baitul Maal Wa At Tamwil (BMT) is a sharia financial institution that provides savings and loan services in accordance with the social, cultural, and economic needs of rural communities, especially in agricultural and plantation communities. The current data management is still using manual recording and a centralized server which can cause fraudulent financial reports and creates a lack of credibility between BMT and its customers. The research method is to decentralize the application data system by using blockchain technology, then replacing the conventional database to blockchain system. The simulation shows that the e-BMT application are connected to blockchain network as intended, users can use metamask to interact with the Ethereum network, the blockchain implementation on e-BMT application has run according to expectations with a 100% success rate with the average transfer time on two devices of 9.47 seconds and 12.13 seconds. While the results of data entry time on two devices obtained an average of 9.96 seconds and 37.09 seconds. While the blockchain implementation on e-BMT could provide access to every user so that each entity could confirm the validity of the transactions, the size of the transactions, and other data recorded on the blockchain without having to develop an integrated database system. The research contributes in two aspects, first, we develop the distributed blockchain system using public Ethereum blockchain network integrated with with popular e-wallet such as metamask, provides easy access for both customers and BMT parties who are connected to the network so that the recorded data can be accessed by anyone, and second, the application of blockchain technology to BMT is capable to interact with users as it is built on a website platform with RESTful API.

The issue of admissibility of evidence in modern legal doctrine is difficult to overestimate, because it is this category of criminal proceedings that is one of the guarantees of its legality. At the same time, each of the possible types of evidence in criminal proceedings contains a system of its own characteristics and features that are related to its admissibility. This also applies to blockchain systems. It is worth noting that as of today, when martial law is in effect in Ukraine, the situation with the proper conduct of criminal proceedings has become somewhat more complicated. Within the framework of this work, the issue of understanding blockchain systems, their advantages and disadvantages was highlighted. According to the author’s algorithm, a study was conducted and the belonging of blockchain systems to electronic evidence was argued. This algorithm included the isolation of the characteristics of electronic evidence mentioned in the scientific literature and their comparison with the characteristics of blockchain systems. As a result, it was stated that blockchain systems belong to electronic evidence. The following should also be distinguished. In cases where blockchain is involved, the blockchain itself is a source of evidence, and cryptocurrency is actually evidence, because cryptocurrency is a digital asset, exists thanks to blockchain technology, is recorded in the form of transactions in the blockchain, and does not exist outside the corresponding blockchain network. The publication also prepared an overview and a substantive description of the most common investigative actions, as a result of which it is possible to obtain a blockchain system as a source of evidence: inspection (Article 237 of the Code of Criminal Procedure of Ukraine), temporary access to things and documents (Articles 159-166 of the Code of Criminal Procedure of Ukraine), search (Article 234 of the Code of Criminal Procedure of Ukraine), interrogation (Article 224 of the Code of Criminal Procedure of Ukraine), conducting an examination (Article 242 of the Code of Criminal Procedure of Ukraine), removal of information from electronic information systems (Article 263 of the Code of Criminal Procedure of Ukraine), control over the commission of a crime (Article 271 of the Code of Criminal Procedure of Ukraine), audio and video surveillance of a person (Article 260 of the Code of Criminal Procedure of Ukraine). In general, the peculiarity of the admissibility of blockchain systems as a source of evidence during martial law is associated with such objective circumstances as military operations that cause disruptions in the operation of electronic networks, the lack of stable access to the Internet, and the limited ability to attract specialists and experts in the field of digital technologies. This, in turn, complicates the proper recording of blockchain data, verification of their authenticity, and documentation of the evidence collection process. Further scientific research is required on the role and significance of blockchain systems as evidence, as well as the issues of their admissibility in civil, administrative, and commercial proceedings.

The impact of communication transmission delay on the original blockchain, has not been well considered and studied since it is primarily designed in stable wired communication environment with high communication capacity. However, in a wireless scenario, due to the scarcity of spectrum resource, a blockchain user may have to compete for wireless channel to broadcast transactions following media access control (MAC) mechanism. As a result, the communication transmission delay may be significant and pose a bottleneck on the blockchain system performance and security. To facilitate blockchain applications in wireless industrial Internet of Things (IIoTs), this article aims to investigate whether the widely used MAC mechanism, carrier sense multiple access/collision avoidance (CSMA/CA), is suitable for wireless blockchain networks or not. Based on tangle, as an example to analyze the system performance in term of confirmation delay, transaction per second and transaction loss probability by considering the impact of queueing and transmission delay caused by CSMA/CA. Next, a stochastic model is proposed to analyze the security issue taking into account the malicious double-spending attack. Simulation results provide valuable insights when running blockchain in wireless network, the performance would be limited by the traditional CSMA/CA protocol. Meanwhile, we demonstrate that the probability of launching a successful double-spending attack would be affected by CSMA/CA as well.

Career management in a global company with employees from various countries is a strategic process that manages, develops, and facilitates the professional growth of employees in a multinational environment. This process involves career planning, competency development, and adjustment to cultural and regulatory diversity in various jurisdictions. The diversity of employees from several different countries impacts the competition to fill specific positions, so transparency about employee career paths in the company is needed. Currently, no system supports career management in global companies that provides transparency of employee career paths, so employees do not know the certainty of their careers in the company. The purpose of this research is to develop a blockchain sharding model for a global company that ensures transparency in the career paths of employees from various countries. By implementing blockchain technology, every transaction related to the career paths of employees from several countries will be validated by each node on the blockchain network. Blockchain technology applies peer-to-peer validation to each transaction before storing it on the blockchain network. This research selects blockchain sharding to enhance the efficiency of the validation process, which spans multiple countries. The study employs a qualitative approach that includes a literature review and software simulation using Hyperledger Fabric. Research results show that blockchain technology can increase the transparency of information about employee career levels.

The blockchain network architecture is a promising technology for constructing highly secure Internet of Things (IoT) networks. IoT networks typically consist of many sensors and actuators. Blockchain network technology can be applied to secure control robots in smart factories or for reliable drone delivery in smart cities. The distributed ledger and data block validation across blockchain networks guarantee the ultimate data security. However, the current blockchain technology is restricted in terms of its overall deployment across IoT networks. A general permissionless blockchain technology typically targets high-performance network nodes with sufficient computing power and memory space. A blockchain node with less computing power and memory, such as an IoT sensor or actuator, cannot employ blockchain technology as a fully functional node. A lightweight blockchain provides practical blockchain availability to IoT networks. We propose an operational advance to develop a lightweight blockchain for IoT networks. The opportunistic block validation optimizes the block validation process. It measures the network vulnerability based on the node reputation, block validation degree, number of fraudulent messages, and network stability. The reinforcement learning mechanism employed in the opportunistic block validation determines whether block validation is to be performed. Two separately developed reinforcement learning methods can increase the processing performance while maintain the transaction data integrity. In addition, the proposed blockchain technology is easily implementable because it adopts a Hyperledger development environment. Directly embedding the proposed blockchain middleware platform in small computing devices proves the practicability of the proposed block validation mechanism.

Approaches to Adopt Blockchain Technology for Internet of Things

Blockchain (BC) is a new technology that has been utilized to create innovative approaches in a variety of industries inclusive of healthcare. The Blockchain Network (BCN) is utilized in the HealthCare Sector (HCS) to protect and communicate patient data across hospitals, pharmacies, clinicians and diagnostic laboratories. The BC applications are capable of identifying serious as well as deadly errors in the healthcare sector. As a result, it is potential to revolutionize the performance, transparency and security of medical details sharing in the HCS. This kind of technology allows medical organizations to acquire knowledge and improve the medical record analysis. Scalability is a significant challenge to Blockchain Technology (BCT) that restricts its capacity for widespread adoption in large-scale transactions applications. This research provides a novel solution to this problem by incorporating the Snake Optimization Algorithm (SOA) into a BCT to improve the rate of transactions and reduce delay. A detailed literature study situates our approach within the present state of BC scalability initiatives which offer a mechanism for incorporating SOA towards the transaction authentication process in BCN. The findings reveal a significant reduction of latency using optimized system has attained faster average transaction rates through a range of transaction amount. The results of this research show that SOA is extremely effective in batch transactions events that exhibit a reverse scalability trend than traditional BCN and substantial contribution to BC scalability with consequences for the creation of improved and scalable BCN ideal for high-volume business applications.

Incentivizing cooperative relay in UTXO-based blockchain network

In these years, Blockchain technology is growing in importance thanks to cryptocurrencies. This technology offers many features such as the immutability of data stored in the data chain, the replicability of data in nodes, the management without a central repository, etc. These features are widely adopted also in other fields such as in distributed measurement systems. Although the Blockchain technology is widespread worldwide, there is still a legislative gap in the adoption of this technology in various states. This paper will examine the challenge and future trends on distributed measurement systems based on Blockchain technology in the European context. In particular, critical aspects of Blockchain technology will be examined under GDPR point of view and in particular in the management of data and privacy. The advantages and disadvantages of using Blockchain technology in applications such as the Internet of Things and smart contracts will be discussed and some aspects of legal metrology in Blockchain networks will be analyzed. At the end, future trends in Blockchain technology applied to distributed measurement systems will be shown.