Lightweight clients are gaining increasing adoption in existing blockchain deployments, owing to their reduced resource consumption. There are currently a number of libraries that implement lightweight clients (e.g., BIP37, Electrum, LES, filter commitments). Notice that these libraries are intrinsically different and require significant effort to be integrated across blockchain platforms. Additionally, lightweight clients require the cooperation of full nodes, which are expected to invest in their computational (to run filters) and bandwidth resources in order to serve lightweight clients. Existing blockchains however offer no rewards for full nodes in exchange-which offers little incentives for full nodes to correctly serve lightweight clients.
Abstract This chapter considers the regulatory regime for cryptocurrencies and other value data (defined as assets which are both excludable and rivalrous, recorded by a trusted technology rather than booked by a qualified intermediary). It begins with a discussion of changes in selected monetary assets and manifestations — namely banknotes and central bank reserve balances — that have occurred over time. It then describes three modes of money creation and their effect on the substance of an asset: money created on a temporary basis; outright money created with no connected reversal event; and by issue of helicopter money. It also analyses the different forms in which cryptocurrencies manifest themselves and their consequences for the rules governing title, transfer and protection of commercial dealings. Finally, it explores the excludable and rivalrous nature of value data and the manifestation of such data by entry in a register kept by a trusted technology.
Privacy in online applications has drawn tremendous attention in recent years. With the development of cloud-based applications, protecting users' privacy while guaranteeing the expected service from the server has become a significant issue. This paper surveyed the most popular cryptographic algorithms in privacy-preserving online applications to provide a tutorial-like introduction to researchers in this area. Specifically, this paper focuses on introduction to homomorphic encryption, secret sharing, secure multi-party computation and zero-knowledge proof.
Gaby G. Dagher, Praneeth Babu Marella, Matea Milojkovic, Jordan Mohler
Voting is a fundamental part of democratic systems; it gives individuals in a community the faculty to voice their opinion. In recent years, voter turnout has diminished while concerns regarding integrity, security, and accessibility of current voting systems have escalated. E-voting was introduced to address those concerns; however, it is not cost-effective and still requires full supervision by a central authority. The blockchain is an emerging, decentralized, and distributed technology that promises to enhance different aspects of many industries. Expanding e-voting into blockchain technology could be the solution to alleviate the present concerns in e-voting. In this paper, we propose a blockchain-based voting system, named BroncoVote, that preserves voter privacy and increases accessibility, while keeping the voting system transparent, secure, and cost-effective. BroncoVote implements a university-scaled voting framework that utilizes Ethereum’s blockchain and smart contracts to achieve voter administration and auditable voting records. In addition, BroncoVote utilizes a few cryptographic techniques, including homomorphic encryption, to promote voter privacy. Our implementation was deployed on Ethereum’s Testnet to demonstrate usability, scalability, and efficiency.
Open access
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
Michał Pawlak, Aneta Poniszewska-Marańda, Natalia Kryvinska
There are many existing voting solutions which have different benefits and issues. The most significant ones are lack of transparency and auditability. Recently developed blockchain technology may be a solution to these issues. The paper describes the use of intelligent agents and multi-agent system concept for Auditable Blockchain Voting System (ABVS), which integrates e-voting process with blockchain technology into one supervised non-remote internet voting system which is end-to-end verifiable.
Sepideh Avizheh, Reihaneh Safavi–Naini, Siamak F. Shahandashti
BIP70 is the Bitcoin payment protocol for communication between a merchant and a pseudonymous customer. McCorry et al. (FC~2016) showed that BIP70 is prone to refund attacks and proposed a fix that requires the customer to sign their refund request. They argued that this minimal change will provide resistance against refund attacks. In this paper, we point out the drawbacks of McCorry et al.'s fix and propose a new approach for protection against refund attacks using the Bitcoin multi-signature mechanism. Our solution does not rely on merchants storing refund requests, and unlike the previous solution, allows updating refund addresses through email. We discuss the security of our proposed method and compare it with the previous solution. We also propose a novel application of our refund mechanism in providing anonymity for payments between a payer and payee in which merchants act as mixing servers. We finally discuss how to combine the above two mechanisms in a single payment protocol to have an anonymous payment protocol secure against refund attacks.
Modern retail banking creates a kind of panopticon for consumer behaviour, ultimately promising to implement a mechanism that binds all of the financial activities undertaken by an individual to a single, unitary identity. In the age of Big Data, consumers have legitimate reasons to resist such surveillance, particularly in cases wherein monitoring is carried out without their knowledge and judgments based upon such monitoring are used to disincentivise or punish legitimate activities. The risk to consumers increases with the ever-increasing share of financial transactions that are performed electronically. Cryptocurrencies offer an alternative to traditional methods of electronic value exchange, promising anonymous, cash-like electronic transfers, but in practice they fall short for several key reasons. We consider the false choice between total surveillance, as represented by banking as currently implemented by institutions, and impenetrable lawlessness, as represented by privacy-enhancing cryptocurrencies as currently deployed. We identify a range of alternatives between those two extremes, and we consider two potential compromise approaches that offer both the auditability required for regulators and the anonymity required for users
Based on the blockchain, homomorphic ElGamal encryption and ring signature, an electronic voting scheme based on blockchain is proposed for large-scale voting, which has the properties of decentralization, self-management, non-interactive and free-receipt, furthermore the one-time ring signature ensures the anonymity of the vote trading in the blockchain. The public verifiable billboards guarantee the voting fair, and the miner nodes provides ciphertext ballot counting service makes large-scale voting feasible. Finally, we analysis the security of the blockchain voting system and present the performance in large-scale nodes.
Open access
Internet Traffic Analysis and Secure E-voting
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
In this paper, we propose a novel blockchain‐based contractual routing (BCR) protocol for a network of untrusted IoT devices. In contrast to conventional secure routing protocols in which a central authority (CA) is required to facilitate the identification and authentication of each device, the BCR protocol operates in a distributed manner with no CA. The BCR protocol utilizes smart contracts to discover a route to a destination or data gateway within heterogeneous IoT networks. Any intermediary device can guarantee a route from a source IoT device to a destination device or gateway. We compare the performance of BCR with that of the Ad-hoc On‐Demand Distance Vector (AODV) routing protocol in a network of 14 devices. The results show that the routing overhead of the BCR protocol is 5 times lower compared to AODV at the cost of a slightly lower packet delivery ratio. BCR is fairly resistant to both Blackhole and Greyhole attacks. The results show that the BCR protocol enables distributed routing in heterogeneous IoT networks.
Blockchain-based cryptocurrencies have demonstrated how to securely implement traditionally centralized systems, such as currencies, in a decentralized fashion. However, there have been few measurement studies on the level of decentralization they achieve in practice. We present a measurement study on various decentralization metrics of two of the leading cryptocurrencies with the largest market capitalization and user base, Bitcoin and Ethereum. We investigate the extent of decentralization by measuring the network resources of nodes and the interconnection among them, the protocol requirements affecting the operation of nodes, and the robustness of the two systems against attacks. In particular, we adapted existing internet measurement techniques and used the Falcon Relay Network as a novel measurement tool to obtain our data. We discovered that neither Bitcoin nor Ethereum has strictly better properties than the other. We also provide concrete suggestions for improving both systems.
The blockchain is a technology designed to verify whether online financial transaction data has been tampered with or not. It has been proven to be reliable as it has been introduced into various fields requiring reliability as well as financial institutions around the world. As the introduction of blockchain technology is expected to bring about a lot of changes in the public service sector, technology adoption is also being reviewed in many countries around the world. In particular, the introduction of blockchain technology in the online voting sector has the advantage of enhancing the reliability, transparency and efficiency of voting. Therefore, in this paper, we analyze the institutional and technical problems that may occur when applying the blockchain technology to online voting system, and suggest ways of using it.
As in 2009 the first encrypted electronic currency Bitcoin is introduced, the block chain technology has received attention. Bitcoin is a currency issued without a trusted third party, in peer-to-peer (Peer-to-Peer) network and gives a guarantee of the reliability of money transactions, ensures the integrity of transactions. There is a back end-technique called block-chain that guarantees these without trusted third party. Block chain is a public ledger that all nodes to verify transactions and maintain integrity with the same ledger. Block chain technology applies not only electronic currency but also in various industries such as contract document integrity, cloud storage service, internet of thigns, supply chain for transaction integrity. However, there are problems to be solved if the bitcoin block chain consensus rule is applied to these industry. First, there is problem of low transaction throughput and block generation rate by an inefficient consensus rule. Second, There is problem of tampered block broadcast with non-dependency (internet of things data, food history data) transactions when applying the block chain consensus rule, which is proof-of-work of bitcoin's competitive system.
Bitcoin is promoted as decentralized cryptocurrency by using pseudonym to achieve anonymity. Unfortunately, numerous seminal works have demonstrated that Bitcoin only offers weak anonymity in practice. Indeed, the practical technologies of clustering and flow analysis are much effective for tracing Bitcoin transaction and thereby revealing the owner involved. Otherwise said, user's privacy in Bitcoin has been sadly degenerated to be linkable. In this paper, we propose a completely decentralized scheme that can provide full anonymity in Bitcoin. The idea behind the output is to exploit a secure escrow address, which is consensual by all the involved users. The escrow address is generated from the trick of cryptographically secure distributed key generation and can then be used for mixing transactions in Bitcoin. Our protocol is secure against malicious adversaries. The users can jointly perform the protocol and successfully accomplish the transaction without the help of any (trusted) third party and no extra fees. Besides, our proposal is completely compatible with the current Bitcoin architecture.
Open access
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
Blockchain is one of the hottest topics in the discussion of technologies lately. As the enabling technology for Bitcoin, the pioneering cryptocurrency, blockchain is an append-only distributed ledger that is virtually impossible to attack given sufficient scale of participants. Hence, blockchain holds great promises as the fundamental technology to enable Internet-based electronic voting. However, Internet-based voting has additional requirements than monetary transactions. In this paper, we analyze these requirements, review existing proposed solutions, and outline possible improvements. Specifically, we propose to use live biometrics of the voter to perform secure and highly reliable remote authentication. We also propose a scheme to protect the secrecy of the ballots and eliminate the influence of votes already cast. Finally, we propose to impose a hierarchy to the voting infrastructure that aligns naturally with traditional voting, which enables parallel processing of multiple blockchains, to overcome the intrinsic scalability limitation of the blockchain technology.
The wisdom of the crowd is a valuable asset in today’s society. It is not only important in predicting elections but also plays an essential role in marketing and the financial industry. Having a trustworthy source of opinion can make forecasts more accurate and markets predictable. Until now, a fundamental problem of surveys is the lack of incentives for participants to provide accurate information. Classical solutions like small monetary rewards or the chance of winning a prize are often not very attractive for participants. More attractive solutions, such as prediction markets, face the issue of illegality and are often unavailable. In this work, we present a solution that unites the advantages from classical polling and prediction markets via a customizable incentivization framework. Apart from predicting events, this framework can also be used to govern decentralized autonomous organizations.
Bitcoin is a cryptocurrency attracting a lot of interest both from the general public and researchers. There is an ongoing debate on the question of users' anonymity: while the Bitcoin protocol has been designed to ensure that the activity of individual users could not be tracked, some methods have been proposed to partially bypass this limitation. In this article, we show how the Bitcoin transaction network can be studied using complex networks analysis techniques, and in particular how community detection can be efficiently used to re-identify multiple addresses belonging to a same user.
Daniel Augot, Hervé Chabanne, Olivier Clémot, William R. George
The most fundamental purpose of blockchain technology is to enable\npersistent, consistent, distributed storage of information. Increasingly common\nare authentication systems that leverage this property to allow users to carry\ntheir personal data on a device while a hash of this data is signed by a\ntrusted authority and then put on a blockchain to be compared against. For\ninstance, in 2015, MIT introduced a schema for the publication of their\nacademic certificates based on this principle. In this work, we propose a way\nfor users to obtain assured identities based on face-to-face proofing that can\nthen be validated against a record on a blockchain. Moreover, in order to\nprovide anonymity, instead of storing a hash, we make use of a scheme of Brands\nto store a commitment against which one can perform zero-knowledge proofs of\nidentity. We also enforce the confidentiality of the underlying data by letting\nusers control a secret of their own. We show how our schema can be implemented\non Bitcoin's blockchain and how to save bandwidth by grouping commitments using\nMerkle trees to minimize the number of Bitcoin transactions that need to be\nsent. Finally, we describe a system in which users can gain access to services\nthanks to the identity records of our proposal.\n
Transactive microgrids are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation, such as wind and solar power. Distributed ledgers have recently found widespread interest in this domain due to their ability to provide transactional integrity across decentralized computing nodes. However, the existing state of the art has not focused on the privacy preservation requirement of these energy systems -- the transaction level data can provide much greater insights into a prosumer's behavior compared to smart meter data. There are specific safety requirements in transactive microgrids to ensure the stability of the grid and to control the load. To fulfil these requirements, the distribution system operator needs transaction information from the grid, which poses a further challenge to the privacy-goals. This problem is made worse by requirement for off-blockchain communication in these networks. In this paper, we extend a recently developed trading workflow called PETra and describe our solution for communication and transactional anonymity.