The current web 2.0 is about connecting people. In which the social media platforms were invented, and the concentration of development was focused on the application layer. There are different approaches to think about web 3.0, some; would say the future is when we have a semantic web others would argue that the future is the virtual web. In this paper, we will talk about another direction to think about the future web called the decentralized web. To enhance the web, we should be concerned with solving the problems that we have and the problems that these platforms have created. The decentralized web is focused on developing protocols and the underlying technologies that are not noticed by end users. This paper gives an overview of the challenges in the current web 2.0. Describes the decentralized web, and what are the technologies that are in development now.
Recently, Blockchain becomes a hot research topic due to the success of Blockchain in many applications, such as cryptocurrency, smart contract, digital assets, distributed cloud storage and so on. The power of Blockchain is that it can achieve the consensus of an ordered set of transactions among nodes which do not trust each other, even with the existence of malicious nodes. However, compared to traditional databases, the current Blockchain technology still cannot handle a massive number of transactions, which is caused by many factors, such as the consensus protocol, structure of the blocks and storage challenge. Among them, the high storage requirement is a key factor that prevents the wide usage of Blockchain on various devices such as mobile phones or low-end PCs. In this paper, to address the storage challenge, we introduce a novel concept called Consensus Unit (CU), which organizes different nodes into one unit and lets them to store at least one copy of Blockchain data in the system together. Based on this idea, we further define the Blocks Assignment Optimization (BAO) problem which determines the optimal assignment of blocks such that the storage space is fully used and the query cost is minimized. We prove that the BAO problem is NP-hard. Thus, we propose three efficient heuristic algorithms to solve the static assignment problem. Furthermore, we present solutions to address the dynamic scenarios when new blocks arrive and nodes join or depart from the CU. To verify the effectiveness of CU, we have conducted extensive experiments on synthetic data and BLOCKBENCH [1]. The results have confirmed the superiority of CU in saving the storage and maintaining the system throughput.
Jing Chen, Shixiong Yao, Quan Yuan, Kun He · 6 authors
In recent years, real-world attacks against PKI take place frequently. For example, malicious domains' certificates issued by compromised CAs are widespread, and revoked certificates are still trusted by clients. In spite of a lot of research to improve the security of SSL/TLS connections, there are still some problems unsolved. On one hand, although log-based schemes provided certificate audit service to quickly detect CAs' misbehavior, the security and data consistency of log servers are ignored. On the other hand, revoked certificates checking is neglected due to the incomplete, insecure and inefficient certificate revocation mechanisms. Further, existing revoked certificates checking schemes are centralized which would bring safety bottlenecks. In this paper, we propose a blockchain-based public and efficient audit scheme for TLS connections, which is called Certchain. Specially, we propose a dependability-rank based consensus protocol in our blockchain system and a new data structure to support certificate forward traceability. Furthermore, we present a method that utilizes dual counting bloom filter (DCBF) with eliminating false positives to achieve economic space and efficient query for certificate revocation checking. The security analysis and experimental results demonstrate that CertChain is suitable in practice with moderate overhead.
The Internet of Things (IoT) network of connected devices currently contains more than 11 billion devices and is estimated to double in size within the next four years. The prevalence of these devices makes them an ideal target for attackers. To reduce the risk of attacks vendors routinely deliver security updates (patches) for their devices. The delivery of security updates becomes challenging due to the issue of scalability as the number of devices may grow much quicker than vendors' distribution systems. Previous studies have suggested a permissionless and decentralized blockchainbased network in which nodes can host and deliver security updates, thus the addition of new nodes scales out the network. However, these studies do not provide an incentive for nodes to join the network, making it unlikely for nodes to freely contribute their hosting space, bandwidth, and computation resources. In this paper, we propose a novel decentralized IoT software update delivery network in which participating nodes (referred to as distributors) are compensated by vendors with digital currency for delivering updates to devices. Upon the release of a new security update, a vendor will make a commitment to provide digital currency to distributors that deliver the update; the commitment will be made with the use of smart contracts, and hence will be public, binding, and irreversible. The smart contract promises compensation to any distributor that provides proof-of-distribution, which is unforgeable proof that a single update was delivered to a single device. A distributor acquires the proof-of-distribution by exchanging a security update for a device signature using the Zero-Knowledge Contingent Payment (ZKCP) trustless data exchange protocol. Eliminating the need for trust between the security update distributor and the security consumer (IoT device) by providing fair compensation, can significantly increase the number of distributors, thus facilitating rapid scale out.
Being the largest blockchain with the capability of running smart contracts, Ethereum has attracted wide attention and its market capitalization has reached 20 billion USD. Ethereum not only supports its cryptocurrency named Ether but also provides a decentralized platform to execute smart contracts in the Ethereum virtual machine. Although Ether's price is approaching 200 USD and nearly 600K smart contracts have been deployed to Ethereum, little is known about the characteristics of its users, smart contracts, and the relationships among them. To fill in the gap, in this paper, we conduct the first systematic study on Ethereum by leveraging graph analysis to characterize three major activities on Ethereum, namely money transfer, smart contract creation, and smart contract invocation. We design a new approach to collect all transaction data, construct three graphs from the data to characterize major activities, and discover new observations and insights from these graphs. Moreover, we propose new approaches based on cross-graph analysis to address two security issues in Ethereum. The evaluation through real cases demonstrates the effectiveness of our new approaches.
Roben Castagna Lunardi, Regio A. Michelin, Charles V. Neu, Avelino F. Zorzo
Due to increased number of attacks on the Internet of Things (IoT) devices, the security of IoT networks became critical. Some recent researches proposed the adoption of blockchain in IoT networks without a thorough discussion on the impact of the solution on the devices performance. Furthermore, blockchain employment in the context of IoT can be challenging due to the devices hardware limitations. To fill this gap, this paper proposes an IoT ledger-based architecture to ensure access control on heterogeneous scenarios. This research applies conventional devices used on IoT networks, such as Arduino, Raspberry and Orange Pi boards. Finally, we perform performance evaluation focused on access control of IoT devices and on information propagation through peers on a private IoT network scenario.
Davide Frey, Marc X. Makkes, Pierre-Louis Roman, François Taı̈ani · 5 authors
Blockchains have a storage scalability issue. Their size is not bounded and they grow indefinitely as time passes. As of August 2017, the Bitcoin blockchain is about 120 GiB big while it was only 75 GiB in August 2016. To benefit from Bitcoin full security model, a bootstrapping node has to download and verify the entirety of the 120 GiB. This poses a challenge for low-resource devices such as smartphones. Thankfully, an alternative exists for such devices which consists of downloading and verifying just the header of each block. This partial block verification enables devices to reduce their bandwidth requirements from 120 GiB to 35 MiB. However, this drastic decrease comes with a safety cost implied by a partial block verification. In this work, we enable low-resource devices to fully verify subchains of blocks without having to pay the onerous price of a full chain download and verification; a few additional MiB of bandwidth suffice. To do so, we propose the design of diet nodes that can securely query full nodes for shards of the UTXO set, which is needed to perform full block verification and can otherwise only be built by sequentially parsing the chain.
Σκοπός της παρούσας διπλωματικής εργασίας είναι η εξέταση της τεχνολογίας που κρύβεται πίσω από τα κρυπτονομίσματα. Η τεχνολογία αυτή είναι το Blockchain και συγκεκριμένα το Blockchain Ethereum, το οποίο είναι μια δημόσια αποκεντρωμένη και κατανεμημένη πλατφόρμα που επιτρέπει σε οποιονδήποτε να δημιουργεί και να χρησιμοποιεί αποκεντρωμένες εφαρμογές που λειτουργούν με αυτή την τεχνολογία. Η καινοτομία της τεχνολογίας Blockchain δίνει λύση στο ζήτημα που αφορά την συγχρονισμένη καταγραφή δεδομένων σε ένα κατανεμημένο δίκτυο από ανεξάρτητους και άγνωστους μεταξύ τους κόμβους (υπολογιστές), συμφωνώντας ότι τα δεδομένα που αποθηκεύονται κάθε φορά είναι ακριβώς τα ίδια. Όλοι οι υπολογιστές που συμμετέχουν σε ένα δίκτυο Blockchain έχουν ακριβώς τα ίδια δεδομένα χωρίς να μπορούν να τα αλλάξουν ή να τα παραμετροποιήσουν, ενώ η ασφάλεια αυτών των δεδομένων επιτυγχάνεται μέσω της κρυπτογραφίας. \nΧρησιμοποιώντας λοιπόν την τεχνολογία Ethereum Blockchain, επιχειρήθηκε η δημιουργία μιας αποκεντρωμένης κατανεμημένης εφαρμογής σε συνεργασία με την εταιρία Intelen Inc. Συγκεκριμένα, έγινε χρήση της τεχνολογίας Blockchain για να επιτευχθεί επικοινωνία μεταξύ έξυπνων οικιακών μπαταριών χωρίς να απαιτείται η παρέμβαση οποιασδήποτε κεντρικής αρχής. Με άλλα λόγια δημιουργήθηκε σχετική εφαρμογή όπου οι έξυπνες μπαταρίες είναι σε θέση να χρησιμοποιήσουν το προσωπικό τους ηλεκτρονικό πορτοφόλι για να ανταλλάζουν κρυπτονομίσματα και πληροφορίες χωρίς την παρέμβαση από τρίτα άτομα.
Shivika Narang, Praphul Chandra, Shweta Jain, Y. Narahari
The blockchain concept forms the backbone of a new wave technology that promises to be deployed extensively in a wide variety of industrial and societal applications. In this article, we present the scientific foundations and technical strengths of this technology. Our emphasis is on blockchains that go beyond the original application to digital currencies such as bitcoin. We focus on the blockchain data structure and its characteristics; distributed consensus and mining; and different types of blockchain architectures. We conclude with a section on applications in industrial and societal settings, elaborating upon a few applications such as land registry ledger, tamper-proof academic transcripts, crowdfunding, and a supply chain B2B platform. We discuss what we believe are the important challenges in deploying the blockchain technology successfully in real-world settings.
This article suggests that the worldwide relevance of blockchain technology is motivated by the changes that it is expected to cause in: (i) the way that business is organised and (ii) regulated, as well as (iii) by the way that it changes the role of individuals within a society. The article presents an overview of the features of blockchain technology. It then takes a closer look into the developments within the energy sector across the world to gain a preliminary indication of whether the stated expectations are coming to reality. As a result of this review, we remain cautiously optimistic that blockchain technology could deliver the expected impact.
Blockchain, as secure means for asset transfer, greatly attracts the attention of the global economic community. However, scalability strongly hampers the growth of economic systems based on the blockchain technology. Bidirectional micropayment channels are suitable solutions for scalability on economic systems based on blockchain. However, the challenge presented by micropayment channels is the inefficient routing mechanisms and timelocks generated per channel for a given path chosen to execute a transaction. In this paper, we develop suitable routing algorithms for economic systems based on blockchain. We additionally derive suitable equations to generate unique timelocks for channels belonging to selected paths chosen to execute a transaction. Finally, we demonstrate the efficiency of the protocol based on number of connections and bandwidth with evidence showing the efficiency and scalability of the routing mechanism.
With the advancements in Internet technologies and Wireless Sensor Networks (WSN), a new era of the Internet of Things (IoT) is being realized. IoT produces a lot of information which can be used to improve the efficiency of our daily lives and provides advanced services in a wide range of application domains. However, the privacy and the data fusing problems remain major challenges, mainly due to the massive scale and distributed nature of IoT networks and the amount of data collected from IoT increasing at an exponential rate. Thus, a privacy-protected and inter-cloud data fusing platform is needed to the demand for data mining and analytic activities in IoT. In this paper, we propose such a platform based on JointCloud Blockchain and study a novel case of smart traveling based on the proposed platform.
JointCloud is a new generation of cloud computing model which facilitates developers to customize cloud services. JCLedger is a blockchain based distributed ledger for JointCloud computing which can make cloud resources exchange more reliable and convenient, and it is the combination of JointCloud and BlockChain. One of the most important elements for creating JCLedger is the consensus algorithm. PoW (Proof of Work) is the consensus algorithm for Bitcoin, which is proved to be quite safe but needs much computing power. The original PoW is not suitable for JCLedger because the identities of participants are not equal in computing power, which may lead to accounting monopoly, and the throughput cannot satisfy the requirement of the massive and high-frequency transactions in JointCloud. In this paper, we propose a PoW based consensus algorithm called Proof of Participation and Fees (PoPF), which can save much computing power and handled transactions more efficiently for JCLedger. In our design, only the candidates have the opportunities for mining and the candidates are chosen according to the ranking which is determined by two factors: the times of the participant to be the accountant and the fees the participant has paid. The difficulty for candidates of solving the PoW hash puzzle is different (the higher ranking means easier for mining). The simulation experiment shows that the distribution of accountants is well-balanced, that is to say, the unequal computing power of participants in JointCloud is shielded, and all the users who have enough contribution in JCLedger will have the opportunities to be accountants.
Blockchain is a distributed ledger system based on P2P network and originally used for a crypto currency system. The P2P network of Blockchain is maintained by full nodes which are in charge of verifying all the transactions in the network. However, most Blockchain user nodes do not act as full nodes, because workload of full nodes is quite high for personal mobile devices. Blockchain search queries, such as confirming balance, transaction contents, and transaction histories, from many users go to the full nodes. As a result, search throughput of full nodes would be a new bottleneck of Blockchain system, because the number of full nodes is less than the number of users of Blockchain systems. In this paper, we propose an acceleration method of Blockchain search using GPUs. More specifically, we introduce an array-based Patricia tree structure suitable for GPU processing so that we can make effective use of Blockchain feature that there are no update and delete queries. In the evaluations, the proposed method is compared with an existing GPU-based key-value search and a conventional CPU-based search in terms of the throughput of Blockchain key search. As a result, the throughput of our proposal is 3.4 times higher than that of the existing GPU-based search and 14.1 times higher than that of the CPU search when the number of keys is 80 ×2^20 and the key length is 256-bit in Blockchain search queries.
Mar 1, 2018·2018 Internat2018 International Conference on Computation of Power, Energy, Information and Communication (ICCPEIC)ional conference on computation of power, energy, Information and Communication (ICCPEIC)
Cryptocurrencies have transpired as one of the trending financial software systems. They depend on a secure and consigned ledger data structure; mining being an indispensable part of such systems. Mining reconsiliates records of past transactions to the distributed register known as the Blockchain, that allows users to reach secure, robust and concord for each transaction. Mining also introduces wealth in the form of new units of currency named as “bitcoins”. Cryptocurrencies lack a central delegate or authority to mediate transactions because they were designed as peer to-peer end sub-systems. They rely on miners to validate and scrutinize their transactions. Hence Cryptocurrencies require a strong, secure mining algorithms. In this article we survey, compare and contrast the current mining techniques as used by major Cryptocurrencies. We scrutinize the strengths, weaknesses, and possible threats to mining strategy. Overall, a perspective on how Cryptocurrencies mine the datasets, where they have comparable performance and assurance, and where they have unique threats and strengths are outlined.
Wireless network virtualization is regarded as an emerging paradigm to enhance RF spectrum utilization to support exponentially increasing demand caused by emerging Internet-of-Things (IoT) applications. To create virtual wireless networks (VWNs), there are no automated secure approaches for allocating RF spectrum to meet the dynamically changing quality-of-service (QoS) requirements of the users. In wireless networks, RF spectrum is shared among many users and the given RF spectrum could be easily overcrowded because of the over commitment of limited resources by the service providers. There is a direct incentive in terms of revenue to service providers to have more number of users. In this paper, we propose to leverage a distributed Blockchain - also known as a public ledger - based scheme to create VWNs where primary wireless resource-owners (PWROs) sublease their wireless resources (e.g., slice of RF spectrum, infrastructure) to mobile virtual network operators (MVNOs) using machine-to-machine communication based on the service level agreements (SLAs) between PWROs and MVNOs. The proposed distributed Blockchain-based scheme provides security to participating PWROs and MVNOs as well as prevents PWROs from over committing their resources (that stops double spending) and helps MVNOs to meet the QoS requirements of their users. The US Federal Communications Commission (FCC) or similar regulatory bodies in other countries participate in this framework by providing the guidelines and regulations about maximum power levels, licensing and geographic coverages, etc. This essentially helps users to meet their desired QoS requirements while complying the government regulations. Performance is evaluated using numerical results.
In this paper, we aim to provide a power trade system that will promote a sustainable electrical energy transaction ecosystem between prosumers and consumers of smart homes. We suggest a blockchain-based peer-to-peer (P2P) energy transaction platform be implemented to enable efficient electrical energy transaction between prosumers. We suggest the platform be built on the blockchain, as this technology allows a decentralized and distributed trading system, and allows a more transparent, trustworthy and secure P2P trading environment. We believe that such characteristics of the blockchain are necessary in electrical energy transactions within the smart home environment because the smart home aims to enhance user comfort and security, along with energy conservation and cost-savings. First, we classify the two different types of P2P trade to identify which will best benefit from the use of the suggested blockchain-based P2P energy-transaction platform. Within the two types of P2P trade, that we classify (pure P2P trade and hybrid P2P trade), the hybrid P2P trade will benefit more from a blockchain-based P2P energy-transaction platform. In the blockchain-based P2P energy-transaction platform, a smart contract is embedded in the blockchain and called an energy tag. The energy tag will set conditions for making every future energy transaction more cost-efficient while maintaining the most ideal and high-quality energy selection. With the blockchain-based energy tag in the energy-transaction process, multiple energy resources and home appliances will be democratically connected in order to provide users with high-quality, low-cost energy at all times and locations. In this paper, we provide simulation results that compare the unit price of electrical energy on the suggested platform to the unit price of electrical energy set by currently existing conventional power-generation companies. Additionally, we present simulation results that calculate how long initial investments to create a smart home environment that enables P2P energy transactions will take to be paid back. Based on simulation results, we believe that, in the long run, the suggested blockchain-based P2P energy-transaction platform will create a sustainable energy-transaction environment between consumers and prosumers, and the expanding ecosystem will enable the development of a trusted, sustainable, secure and energy-efficient energy transaction environment.
Sheng Wang, Tien Tuan Anh Dinh, Qian Lin, Zhongle Xie · 10 authors
Existing data storage systems offer a wide range of functionalities to accommodate an equally diverse range of applications. However, new classes of applications have emerged, e.g., blockchain and collaborative analytics, featuring data versioning, fork semantics, tamper-evidence or any combination thereof. They present new opportunities for storage systems to efficiently support such applications by embedding the above requirements into the storage. In this paper, we present ForkBase, a storage engine specifically designed to provide efficient support for blockchain and forkable applications. By integrating the core application properties into the storage, ForkBase not only delivers high performance but also reduces development effort. Data in ForkBase is multi-versioned, and each version uniquely identifies the data content and its history. Two variants of fork semantics are supported in ForkBase to facilitate any collaboration workflows. A novel index structure is introduced to efficiently identify and eliminate duplicate content across data objects. Consequently, ForkBase is not only efficient in performance, but also in space requirement. We demonstrate the performance of ForkBase using three applications: a blockchain platform, a wiki engine and a collaborative analytics application. We conduct extensive experimental evaluation of these applications against respective state-of-the-art system. The results show that ForkBase achieves superior performance while significantly lowering the development cost.
Blockchains have revolutionized the storage of data in an immutable, transparent and non-centralized way. However, public blockchain systems like the Bitcoin system face a problem of scalability, primarily due to the significant and growing size of its blockchain. This paper introduces a method, termed block summarization, which reduces blockchain storage overhead for systems having transferable transactions. The proposed method allows resource-restricted light nodes to store a form of the blockchain such that it can validate the transactions independently which ultimately reduce dependency on full nodes. This way, we can achieve a middle ground between Simplified Payment Verification (SPV) nodes which can only verify the membership of a transaction in the blockchain, and full nodes with pruning enabled which can only support pruning provided they have an infrastructure of full nodes. We implemented our algorithm for a custom blockchain using Bitcoin blocks and were able to achieve a compression ratio of 0.54.
The recent explosion of interest in blockchains led to a plethora of proposals for their application, including attempts to decentralize some centralized network functions. At the same time, real "distributed wireless networks" are emerging. Community networks, for instance, are large mesh networks made of hundreds of nodes built by communities primarily to solve digital divide, and they are thriving. The challenges these networks face are not only technological: they deal with creating incentives to participate, with the business model they may adopt, and with their internal governance. Very few models have been proposed to apply blockchains to bottom-up distributed networks: we instead expose how they can solve many problems which so far hindered the diffusion of such networks. Maybe we can push this further: a network is, in essence, a system in which all nodes find a rough consensus on the best paths to connect a node with another. Can we use this consensus method to run a distributed ledger and a cryptocurrency within the network itself, rather than simply applying to networks the effects of a blockchain defined in a separate system? This paper introduces this concept, named "Proof of Networking", and discusses its potential avails.
Digital banking as an essential service can be hard to access in remote, rural regions where the network connectivity is unavailable or intermittent. The payment operators like Visa and Mastercard often face difficulties reaching these remote, rural areas. Although micro-banking has been made possible by short message service or unstructured supplementary service data messages in some places, their security flaws and session-based nature prevent them from wider adoption. Global-level cryptocurrencies enable low-cost, secure, and pervasive money transferring among distributed peers, but are still limited in their ability to reach people in remote communities. We propose a blockchain-based digital payment scheme that can deliver reliable services on top of unreliable networks in remote regions. We focus on a scenario where a community-run base station provides reliable local network connectivity while intermittently connects to the broader Internet. We take advantage of the distributed verification guarantees of the Blockchain technology for financial transaction verification and leverage smart contracts for secure service management. In the proposed system, payment operators deploy multiple proxy nodes that are intermittently connected to the remote communities where the local blockchain networks, such as Ethereum are composed of miners, vendors, and regular users. Through probabilistic modeling, we devise design parameters for the blockchain network to realize robust operation over the top of the unreliable network. Furthermore, we show that the transaction processing time will not be significantly impacted due to the network unreliability through extensive emulations on a private Ethereum network. Finally, we demonstrate the practical feasibility of the proposed system by developing Near Field Communication (NFC)-enabled payment gateways on Raspberry-Pis, a mobile wallet application and mining nodes on off-the-shelf computers.
Bitcoin is a peer-to-peer electronic currency without central bank controlling. Nowadays, increasing amount of people are engaged in the mining of Bitcoin for great profits. However, in the Bitcoin system, the more participants in the system, the greater computation power of the whole network and the less efficiency in the output of the coin, since large computational power of the whole Bitcoin system will lead to increased difficulty for a single miner to mine a new data block. At the same time, when more than 51% computing power is controlled by a single node, it could destroy the Bitcoin system. In order to reduce ineffective mining behaviors, one would wish to employ the optimal selection mechanism of different miners. This paper will mainly develop the model in which small miners (those who have relative smaller computational power in a block mining) join the major ones based on revenue, computational power cost, and other elements of the process comparing to the current model (when they work separately).
Blockchains enables tamper-proof, ordered logging for transactional data in a decentralized manner over open-access, overlay peer-to-peer networks. In this paper, we propose a decentralized framework of proactive caching in a hierarchical wireless network based on blockchains. We employ the blockchain-based smart contracts to construct an autonomous content caching market. In the market, the cache helpers are able to autonomously adapt their caching strategies according to the market statistics obtained from the blockchain, and the truthfulness of trustless nodes are financially enforced by smart contract terms. Further, we propose an incentive-compatible consensus mechanism based on proof-of-stake to financially encourage the cache helpers to stay active in service. We model the interaction between the cache helpers and the content providers as a Chinese restaurant game. Based on the theoretical analysis regarding the Nash equilibrium of the game, we propose a decentralized strategy-searching algorithm using sequential best response. The simulation results demonstrate both the efficiency and reliability of the proposed equilibrium searching algorithm.