Blockchain is a disruptive technique that finds many applications in FinTech, IoT, and token economy. Because of the asynchrony of network, the competition of mining, and the nondeterministic block propagation delay, forks in the blockchain occur frequently which not only waste a lot of computing resources but also result in potential security issues. This paper introduces PvScheme, a probabilistic verification scheme that can effectively reduce the block propagation delay and hence reduce the occurrence of blockchain forks. We further enhance the security of PvScheme to provide reliable block delivery. We also analyze the resistance of PvScheme to fake blocks and double spending attacks. The results of several comparative experiments show that our scheme can indeed reduce forks and improve the blockchain performance.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
As of today, web-based social communication platforms, such as WhatsApp, Twitter, or Facebook, are almost exclusively realized via centralized platforms, based on proprietary interfaces, protocols, and data formats. In consequence, even though social communication being a decentralized, peer-to-peer phenomenon, web-based communication today is implemented via closed, proprietary data silos, which not only lock-in users into their service platforms, but also control and own exchange information and data, including personal and sensitive data such as photos, messages, or contact information. In this paper we present Tawki, a decentralized service architecture for social communication. Using Tawki, users remain in full control of their personal data, which is stored and managed by personal data storages. Each data storage is accessible via a unified Tawki API, which allows users to send and request data to and from other users' personal data storages. Following this approach, social communication is again peer-to-peer without involving a third party controlling and monitoring the process. Tawki uses the Ethereum Name Service (ENS) for both the management of user identities and resolving identifiers to the respective user's personal storage location. Leveraging the immutability of the Ethereum Blockchain, identity management and discovery of personal data storages is secured against censorship and control through any third party.
Martijn de Vos, Mitchell Olsthoorn, Johan Pouwelse
Decentralized applications, also known as dApps, are the new paradigm for writing business-critical software. Recruiting developers with appropriate qualifications and skills for this activity is key, yet challenging. The main problem is that the portfolio of developers is usually scattered across centralized platforms like GitHub and LinkedIn, and vendor locked. This can result in an incomplete impression of their capabilities. We address this problem and introduce DevID, a blockchain-based portfolio for developers. Over time, this portfolio enables developers to build up a trustworthy collection of records that showcase their capabilities and expertise. They can import data assets from third parties into a unified DevID portfolio, add projects and skills, and receive endorsements. All portfolio records are stored on a scalable distributed ledger and owned by developers themselves. The essential idea is to exploit the tamper-proof property of the blockchain while providing durable storage. To demonstrate the practical value of DevID, we build the competition-based platform, dAppCoder, for the development of decentralized applications. On dAppCoder clients are able to submit their ideas and developers can find work. dAppCoder utilizes DevID portfolios to match these clients and developers. We fully implement our ideas and conduct a deployment trial. Our trial demonstrates that DevID is efficient at storing portfolio records.
Khalid AlJemy, Mohammed Alanazi, Mohammed AlSofiry, Adeel Baig
Internet of Things (IoT) is the new technology that will change the Internet era in the coming years. IoT can be used in many fields, such as digitally connected factories, facility management, production flow management inventory management, safety, security, health care, logistics, supply chain optimization, and so on. However, due to limited capabilities in IoT, it is impractical to implement extensive security solutions. Also, security standards for IoT are not mature enough. As a result, many security incidents affect IoT reliability. In this paper, we propose an effective security mechanisms that can be implemented to ensure data accuracy and integrity of IoT devices along with considering its limited hardware resources. We implement Blockchain in IoT to enhance IoT security. We apply our approach using the Ethereum protocol by having multiple Raspberry Pi devices connected as peers to the Blockchain. Also, we discuss the implementation and the expected outcome of this project, which is to implement the Access Control List mechanism using Blockchain to improve the overall IoT security and to connect IoT devices to Ethereum as light nodes.
David Chen, Zhiyue Zhang, Ambrish Krishnan, Bhaskar Krishnamachari
We present PayFlow, a fine-granularity QoS micro-payment system that allows end devices in a software-defined network to make and pre-pay for guaranteed bandwidth reservations for their flows within the network for an arbitrary period of time. PayFlow combines payments using digital currency and storage of transaction records in a distributed ledger with queue-based QoS management using software-defined networks. While the PayFlow architecture is agnostic to the choice of digital currency, ledger technology and SDN platform used, we present a proof of concept implementation of PayFlow using OpenFlow and the IOTA cryptocurrency and distributed ledger, that we evaluate using the Mininet emulator.
Blockchains are currently gaining attention as a newly emerging technology in both academia and industry, capable of impacting a variety of domains beyond cryptocurrencies. Performance modeling can be used to provide us with a deeper understanding of the behavior and dynamics within blockchain peer-to-peer networks. Blockchain system architects can leverage network models to properly tune their system and to reduce design costs significantly. In this paper, we focus on the original and well-established Bitcoin blockchain network. In particular, we propose a random graph model for performance modeling and analysis of the inventory-based protocol for block dissemination. This model addresses the impact of key blockchain parameters on the overall performance of Bitcoin. We derive some explicit and closed-form equations for block propagation delay and traffic overhead. We implement our model using the popular network simulator OMNet++. We validate the accuracy of our theoretical model and its implementation with our dataset mined from the Bitcoin network. Our results show the trade-off between the default number of connections per node, network bandwidth, and block size in order to compute the optimal block propagation delay over the network.
While direct allocation of spectrum and evolved medium access protocols provide a base for ubiquitous wireless connectivity, the existing TCP/IP and OSI models were designed for wired networks and do not address open interconnection of air interfaces. Without an interconnection model for the air interface, existing network designs continue to tie wireless medium access to that of the backhaul provider for ownership of access and identity trust, resulting in limitations on functionality and coverage. In this paper, we propose a novel solution to access ownership and identity trust by extending the TCP network standard, under a new model we propose, named TCP-Air which integrates distributed ledger technologies directly at the air interface. Further, we present two use cases of the TCP-Air model, demonstrating applications not feasible under existing permissioned-access network designs.
Caixiang Fan, Hamzeh Khazaei, Yuxiang Chen, Petr Musı́lek
In recent years, Distributed Ledger Technology (DLT) has been playing a more and more important role in building trust and security for Internet of Things (IoT). However, the unacceptable performance of the current mainstream DLT systems such as Bitcoin can hardly meet the efficiency and scalability requirements of IoT. In this paper, we propose a scalable transactive smart homes infrastructure by leveraging a Directed Acyclic Graph (DAG) based DLT and following the separation of concerns (SOC) design principle. Based on the proposed solution, an experiment with 40 Home Nodes is conducted to prove the concepts. From the results, we find that our solution provides a high transaction speed and scalability, as well as good performance on security and micropayment which are important in IoT settings. Then, we conduct an analysis and discuss how the new system breaks out the well-known Trilemma, which claims that it is hard for a DLT platform to simultaneously reach decentralization, scalability and security. Finally, we conclude that the proposed DAG-based distributed ledger is an effective solution for building an IoT infrastructure for smart communities.
As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions have downsides in communication and storage efficiency, convergence to centralization, and consistency problems. In this paper, we propose LightChain, which is the first blockchain architecture that operates over a Distributed Hash Table (DHT) of participating peers. LightChain is a permissionless blockchain that provides addressable blocks and transactions within the network, which makes them efficiently accessible by all the peers. Each block and transaction is replicated within the DHT of peers and is retrieved in an on-demand manner. Hence, peers in LightChain are not required to retrieve or keep the entire blockchain. LightChain is fair as all of the participating peers have a uniform chance of being involved in the consensus regardless of their influence such as hashing power or stake. LightChain provides a deterministic fork-resolving strategy as well as a blacklisting mechanism, and it is secure against colluding adversarial peers attacking the availability and integrity of the system. We provide mathematical analysis and experimental results on scenarios involving 10K nodes to demonstrate the security and fairness of LightChain. As we experimentally show in this paper, compared to the mainstream blockchains like Bitcoin and Ethereum, LightChain requires around 66 times less per node storage, and is around 380 times faster on bootstrapping a new node to the system, while each LightChain node is rewarded equally likely for participating in the protocol.
Andrew Cullen, Pietro Ferraro, Christopher King, Robert Shorten
Directed Acyclic Graph (DAG) based Distributed Ledgers can be useful in a number of applications in the IoT domain. A distributed ledger should serve as an immutable and irreversible record of transactions, however, a DAG structure is a more complicated mathematical object than its blockchain counterparts, and as a result, providing guarantees of immutability and irreversibility is more involved. In this paper, we analyse a commonly discussed attack scenario known as a parasite chain attack for the IOTA Foundation DAG based ledger. We analyse the efficacy of IOTA core MCMC algorithm using a matrix model and present an extension which improves the ledger resistance to these attacks.
Blockchain technology initially developed for transactions on cryptocurrencies is now gaining popularity in major domains such as education, healthcare, media, government, smart computing, and business enterprise. Blockchain manages the transactions database in a decentralized way replicated on all the nodes with no single governing authority. In this paper, we present a classification and taxonomy of different blockchain development platforms and simulators along with their consensus protocols, the types of supported blockchain networks and programming languages. We also assess the performance of a blockchain application for deployment at the UAE University (UAEU) versus increasing number of nodes, blocks and block size, on top of experimental network latencies and bandwidth between the nodes. Our results show that a large-scale deployment of blockchain at UAEU is feasible.
In this paper, we formulate the consensus problem and its solutions as seen in public blockchains and contrast them to those of the traditional distributed consensus. The Proof of Work (PoW) algorithm introduced in Bitcoin provides the first elegant and practical solution for reaching distributed consensus in a large-scale untrusted environment. Due to the enormous energy cost of PoW, many alternative consensus algorithms have been proposed for public blockchains aiming at drastically reducing the energy consumption for reaching consensus. We examine four blockchain consensus algorithms, namely Proof of Work, Proof of Stake, Proof of Space, and Proof of Elapsed Time, with respect to the consensus model we have formulated and point out the challenges of adopting them in public blockchains.
Blockchains are proposed for many application domains apart from financial transactions. While there are generic blockchains that can be molded for specific use cases, they often lack a lightweight and easy-to-customize implementation. In this paper, we introduce the core concepts of blockchain technology and investigate a real-world use case from the energy domain, where customers trade portions of their photovoltaic power plant via a blockchain. This does not only involve blockchain technology, but also requires user interaction. Therefore, a fully custom, private, and permissioned blockchain is implemented from scratch. We evaluate and motivate the need for blockchain technology within this use case, as well as the desired properties of the system. We then describe the implementation and the insights from our implementation in detail, serving as a guide for others and to show potential opportunities and pitfalls when implementing a blockchain from scratch.
While the intersection of blockchain and Industrial Internet of Things (IIoT) has received considerable research interest lately, the conflict between the high resource requirements of blockchain and the generally inadequate performance of IIoT devices has not been well tackled. On one hand, due to the introductions of mathematical concepts, including Public Key Infrastructure, Merkle Hash Tree, and Proof of Work (PoW), deploying blockchain demands huge computing power. On the other hand, full nodes should synchronize massive block data and deal with numerous transactions in peer-to-peer network, whose occupation of storage capacity and bandwidth makes IIoT devices difficult to afford. In this paper, we propose a lightweight blockchain system called LightChain, which is resource-efficient and suitable for power-constrained IIoT scenarios. Specifically, we present a green consensus mechanism named Synergistic Multiple Proof for stimulating the cooperation of IIoT devices, and a lightweight data structure called LightBlock to streamline broadcast content. Furthermore, we design a novel Unrelated Block Offloading Filter to avoid the unlimited growth of ledger without affecting blockchain's traceability. The extensive experiments demonstrate that LightChain can reduce the individual computational cost to 39.32% and speed up the block generation by up to 74.06%. In terms of storage and network usage, the reductions are 43.35% and 90.55%, respectively.
Pietro Danzi, Anders E. Kalør, René Sørensen, Alexander Korsvang Hagelskjær · 7 authors
The pervasive need to safely share and store information between devices calls for the replacement of centralized trust architectures with the decentralized ones. Distributed Ledger Technologies (DLTs) are seen as the most promising enabler of decentralized trust, but they still lack technological maturity and their successful adoption depends on the understanding of the fundamental design trade-offs and their reflection in the actual technical design. This work focuses on the challenges and potential solutions for an effective integration of DLTs in the context of Internet-of-Things (IoT). We first introduce the landscape of IoT applications and discuss the limitations and opportunities offered by DLTs. Then, we review the technical challenges encountered in the integration of resource-constrained devices with distributed trust networks. We describe the common traits of lightweight synchronization protocols, and propose a novel classification, rooted in the IoT perspective. We identify the need of receiving ledger information at the endpoint devices, implying a two-way data exchange that contrasts with the conventional uplink-oriented communication technologies intended for IoT systems.
Pietro Danzi, Anders E. Kalør, René Sørensen, Alexander Korsvang Hagelskjær · 7 authors
The pervasive need to safely share and store information between devices\ncalls for the replacement of centralized trust architectures with the\ndecentralized ones. Distributed Ledger Technologies (DLTs) are seen as the most\npromising enabler of decentralized trust, but they still lack technological\nmaturity and their successful adoption depends on the understanding of the\nfundamental design trade-offs and their reflection in the actual technical\ndesign. This work focuses on the challenges and potential solutions for an\neffective integration of DLTs in the context of Internet-of-Things (IoT). We\nfirst introduce the landscape of IoT applications and discuss the limitations\nand opportunities offered by DLTs. Then, we review the technical challenges\nencountered in the integration of resource-constrained devices with distributed\ntrust networks. We describe the common traits of lightweight synchronization\nprotocols, and propose a novel classification, rooted in the IoT perspective.\nWe identify the need of receiving ledger information at the endpoint devices,\nimplying a two-way data exchange that contrasts with the conventional\nuplink-oriented communication technologies intended for IoT systems.\n
Pascal Berrang, Philipp von Styp-Rekowsky, Marvin Wißfeld, Bruno W. França · 5 authors
The consensus protocol is a critical component of distributed ledgers and blockchains. Achieving consensus over a decentralized network poses challenges to transaction finality and performance. Currently, the highest-performing consensus algorithms are speculative BFT algorithms, which, however, compromise on the transaction finality guarantees offered by their non-speculative counterparts. In this paper, we introduce Albatross, a Proof-of-Stake (PoS) blockchain consensus algorithm that aims to combine the best of both worlds. At its heart, Albatross is a high-performing, speculative BFT algorithm that offers strong probabilistic finality. We complement this by periodically guaranteeing finality through the Tendermint protocol. We prove our protocol to be secure under standard BFT assumptions and analyze its performance both on a theoretical and practical level. For that, we provide an open-source Rust implementation of Albatross. Our real-world measurements support that our protocol has a performance close to the theoretical maximum for single-chain Proof-of-Stake consensus algorithms.
Sandi Rahmadika, Diena Rauda Ramdania, Maisevli Harika
Blockchain technology holds great promise to rewire the current financial system which relies on the third party. Every transaction is recorded in a secure and transparent for the parties in the blockchain network. Blockchain technology in the energy sector becomes an interesting topic among researchers at this moment. The use of blockchain allows producers and consumers to trade energy transactions through smart grids because of a decentralized energy trading system. The trading activities without a third party involved would reduce the cost of a transaction thus it brings to a new level of quality of service in the trading system. In this paper, we propose an architectural model for decentralized energy trading system among the neighbors that allows the producer who has the surplus energy to conduct a trading activity with his/her neighbors. The transactions manage by the miners in the same blockchain network. Moreover, we analyze the security issues from various attacks and presenting the performance of the selected attack that might occur in the model.
With special emphasis being put upon renewable sources of energy day-by-day, there is a growing demand for this new technology to be integrated into the existing framework. To be widely accepted and made sustainable, such a technology should be profitable for all participating entities; giving them incentive enough to continue using it. What remains to be answered is the question of how that will be done. We break down the traditional power grid into smaller clusters, called microgrid and discuss its properties as potential candidates for implementing Blockchain powered energy trading mechanisms. Blockchain enabled technology is chosen as it brings with it, a degree of security, transparency and automation; and cuts out the established monopoly with the decentralized network and peer-to-peer trading. Two such working algorithms are reviewed for their implementation into the microgrid. One algorithm works on an auction model while another is a calculative data-dependent model but both the models function using smart contracts. Pre-existing projects in this field and their implementation around the world are reviewed by us in the later section of the paper. We conclude this paper by encapsulating the deployment considerations and limitations of employing Blockchain technology in a microgrid.
Prior to blockchain technology coming into much usage, the earlier cryptographic digital cash schemes relied merely on trusted authorities. Bitcoin revolutionized this conventional view of a cryptocurrency, trading decentralized, distributed ledger, completely secured by the majority rule without predetermined authority or owner. Only standard cryptographic primitives such as signatures and hash functions were used to achieve security. Though other cryptocurrencies such as Bit-gold and B-money which are among the authority-free cryptocurrencies, Bitcoin is the first one to experience public acceptance on a large scale. There are various factors which contribute to Bitcoins success, though there is still a little question of doubt that the decentralized design of blockchain technology and perceived resilience to government or third-party intervention played an extremely crucial role in its uptake. Distributed crypto cash, more specifically in Blockchain technology has hailed as one key and most eminent and widely accepted innovation of Bitcoin. In this paper we have worked on the use of blockchain technology to implement cryptocurrency for IOT.
R. Aroul Canessane, N. Srinivasan, Abinash Beuria, Ashwini Kumar Singh · 5 authors
The concept of blockchain without a doubt is a revolutionary concept. It is the underlying Technology behind bitcoin and many more cryptocurrencies. Although the people's focus being only at blockchain as cryptocurrencies in everyday services to do payments online without the interference of a third party will try to replace the current method of cash which is a really slow and ancient method. Blockchain is a zero trust network and this makes it a very powerful tool for various services provided that people are ready to believe and invest in it. In the Ethereum world, the blockchain runs on smart contracts which are self-executing applications that come at a cost of security. This zero-trust network is capable of replacing many of the debated process or activities in our day to day life. One of our biggest concerns is an E-voting system which must be secure. Blockchain being an immutable and append only ledger will not allow for any tampering while also being fully transparent. In this paper, we have implemented and tested a sample e-voting app running as a smart contract for ethereum network using E-Wallets. After an election is held, eventually, the ethereum blockchain will hold the records of ballots and voters thus giving us a clear and trusty network where mishandling is to a minimum.
The Internet of Things (IoT) devices currently rely on centralized, brokered communication models which call for a number of security flaws and threats. Privacy & security remain a challenge owing to the existing systems being centralized - creating a single point of failure. In this paper, we lay out an architecture for incorporating a concept similar to Blockchain - the technology that underpins the cryptocurrency Bitcoin and many other cryptocurrencies to provide decentralized security and privacy for IoT devices. Currently, the issue with most IoT devices is that they lack the processing power, storage and computational overhead to run consensus algorithms to be an active part of the Blockchain network. The current issue with the blockchain on the other hand, is its low scalability and low number of transactions per second. We present an innovative approach using a technology called IOTA. This addresses some of the most important problems with existing blockchain infrastructure such as being able to run on lightweight devices with constrained memory. We eliminate transaction fees and the concept of mining which requires a large amount of processing power to compete with other miners. IOTA's main component is the Tangle, a guided acyclic graph (DAG) for transaction storage. We discuss creation of two IoT applications on the tangle - a smart utility meter system and a smart car transaction system which are connected to internet through Low Power Wide Area IoT networks.
With the ever growing Internet of Things (IoT) market, ledger systems are facing new challenges to efficiently store and secure enormous customer records collected by the IoT devices. The authenticity, availability, and integrity of these records are critically important for both business providers and customers. In this paper, we describe DLedger, a lightweight and resilient distributed ledger system. Instead of a single chain of blocks, DLedger builds the ledger over a directed acyclic graph (DAG), so that its operations can tolerate network partition and intermittent connectivity. Instead of compute-intensive Proof-of-Work (PoW), DLedger utilizes Proof-of-Authentication (PoA), whose light-weight operations are IoT-friendly, to achieve consensus. Furthermore, DLedger is built upon a data-centric network called Named Data Networking (NDN), which facilitates the peer-to-peer data dissemination in heterogeneous IoT networks.