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1,224 results · page 37 of 51
Abylay Satybaldy, Mariusz Nowostawski, Jørgen Ellingsen
No abstract is available for this record.
Sarada Prasad Gochhayat, Sachin Shetty, Ravi Mukkamala, Peter Foytik · 6 authors
Blockchain promises to provide a distributed and decentralized means of trust among untrusted users. However, in recent years, a shift from decentrality to centrality has been observed in the most accepted Blockchain system, i.e., Bitcoin. This shift has motivated researchers to identify the cause of decentrality, quantify decentrality and analyze the impact of decentrality. In this work, we take a holistic approach to identify and quantify decentrality in Blockchain based systems. First, we identify the emergence of centrality in three layers of Blockchain based systems, namely governance layer, network layer and storage layer. Then, we quantify decentrality in these layers using various metrics. At the governance layer, we measure decentrality in terms of fairness, entropy, Gini coefficient, Kullback-Leibler divergence, etc. Similarly, in the network layer, we measure decentrality by using degree centrality, betweenness centrality and closeness centrality. At the storage layer, we apply a distribution index to define centrality. Subsequently, we evaluate the decentrality in Bitcoin and Ethereum networks and discuss our observations. We noticed that, with time, both Bitcoin and Ethereum networks tend to behave like centralized systems where a few nodes govern the whole network.
Tin Tironsakkul, Manuel Maarek, Andrea Eross, Mike Just
Mixer services purportedly remove all connections between the input (deposited) Bitcoins and the output (withdrawn) mixed Bitcoins, seemingly rendering taint analysis tracking ineffectual. In this paper, we introduce and explore a novel tracking strategy, called \emph{Address Taint Analysis}, that adapts from existing transaction-based taint analysis techniques for tracking Bitcoins that have passed through a mixer service. We also investigate the potential of combining address taint analysis with address clustering and backward tainting. We further introduce a set of filtering criteria that reduce the number of false-positive results based on the characteristics of withdrawn transactions and evaluate our solution with verifiable mixing transactions of nine mixer services from previous reverse-engineering studies. Our finding shows that it is possible to track the mixed Bitcoins from the deposited Bitcoins using address taint analysis and the number of potential transaction outputs can be significantly reduced with the filtering criteria.
Haya R. Hasan, Khaled Salah, Raja Jayaraman, Junaid Arshad · 7 authors
COVID-19 has emerged as a highly contagious disease which has caused a devastating impact across the world with a very large number of infections and deaths. Timely and accurate testing is paramount to an effective response to this pandemic as it helps identify infections and therefore mitigate (isolate/cure) them. In this paper, we investigate this challenge and contribute by presenting a blockchain-based solution that incorporates self-sovereign identity, re-encryption proxies, and decentralized storage, such as the interplanetary file systems (IPFS). Our solution implements digital medical passports (DMP) and immunity certificates for COVID-19 test-takers. We present smart contracts based on the Ethereum blockchain written and tested successfully to maintain a digital medical identity for test-takers that help in a prompt trusted response directly by the relevant medical authorities. We reduce the response time of the medical facilities, alleviate the spread of false information by using immutable trusted blockchain, and curb the spread of the disease through DMP. We present a detailed description of the system design, development, and evaluation (cost and security analysis) for the proposed solution. Since our code leverages the use of the on-chain events, the cost of our design is almost negligible. We have made our smart contract codes publicly available on Github.
Bruno Rodrigues, Trendafilov Spasen, Eder J. Scheid, Burkhard Stiller
Distributed Denial-of-Service (DDoS) attacks remains as one of the major causes of concerns for service providers around the world. This paper introduces SC-FLARE, a Smart Contract (SC) based cooperative signaling protocol built on top of a Ethereum Proof-of-Authority Blockchain (BC) for the sharing of attack information, the exchange of incentives, and the tracking of reputation in a fully distributed and automated fashion. By making use of BC and SC, SC-FLARE provide the required collaborative platform without the burden to maintain, design, and develop special registries and gossip protocols for a cooperative defense.
Pavlos Papadopoulos, Nikolaos Pitropakis, William J. Buchanan, Owen Lo · 5 authors
The Domain Name System (DNS) was created to resolve the IP addresses of the web servers to easily remembered names. When it was initially created, security was not a major concern; nowadays, this lack of inherent security and trust has exposed the global DNS infrastructure to malicious actors. The passive DNS data collection process creates a database containing various DNS data elements, some of which are personal and need to be protected to preserve the privacy of the end users. To this end, we propose the use of distributed ledger technology. We use Hyperledger Fabric to create a permissioned blockchain, which only authorized entities can access. The proposed solution supports queries for storing and retrieving data from the blockchain ledger, allowing the use of the passive DNS database for further analysis, e.g. for the identification of malicious domain names. Additionally, it effectively protects the DNS personal data from unauthorized entities, including the administrators that can act as potential malicious insiders, and allows only the data owners to perform queries over these data. We evaluated our proposed solution by creating a proof-of-concept experimental setup that passively collects DNS data from a network and then uses the distributed ledger technology to store the data in an immutable ledger, thus providing a full historical overview of all the records.
Weizheng Wang, Chunhua Su
No abstract is available for this record.
Dimitris Karakostas, Aggelos Kiayias, Mario Larangeira
Blockchain protocols based on Proof-of-Stake (PoS) depend—by nature—on the active participation of stakeholders. If users are offline and abstain from the PoS consensus mechanism, the system’s security is at risk, so it is imperative to explore ways to both maximize the level of participation and minimize the effects of non-participation. One such option is stake representation, such that users can delegate their participation rights and, in the process, form “stake pools”. The core idea is that stake pool operators always participate on behalf of regular users, while the users retain the ownership of their assets. Our work provides a formal PoS wallet construction that enables delegation and stake pool formation. While investigating the construction of addresses in this setting, we distil and explore address malleability, a security property that captures the ability of an attacker to manipulate the delegation information associated with an address. Our analysis consists of identifying multiple levels of malleability, which are taken into account in our paper’s core result. We then introduce the first ideal functionality of a PoS wallet’s core which captures the PoS wallet’s capabilities and is realized as a secure protocol based on standard cryptographic primitives. Finally, consider the wallet core in conjunction with a PoS ledger and investigate how delegation and stake pools affect a PoS system’s security.
Zhang Lejun, Zhijie Zhang, Weizheng Wang, Waqas Rasheed · 7 authors
As an extension of the traditional encryption technology, information hiding has been increasingly used in the fields of communication and network media, and the covert communication technology has gradually developed. The blockchain technology that has emerged in recent years has the characteristics of decentralization and tamper resistance, which can effectively alleviate the disadvantages and problems of traditional covert communication. However, its combination with covert communication thus far has been mostly at the theoretical level. The BLOCCE method, as an early result of the combination of blockchain and covert communication technology, has the problems of low information embedding efficiency, the use of too many Bitcoin addresses, low communication efficiency, and high costs. The present research improved on this method, designed the V-BLOCCE which uses base58 to encrypt the plaintext and reuses the addresses generated by Vanitygen multiple times to embed information. This greatly improves the efficiency of information embedding and decreases the number of Bitcoin addresses used. Under the premise of ensuring the order, the Bitcoin transaction OP_RETURN field is used to store the information required to restore the plaintext and the transactions are issued at the same time to improve the information transmission efficiency. Thus, a more efficient and feasible method for the application of covert communication on the blockchain is proposed. In addition, this paper also provides a more feasible scheme and theoretical support for covert communication in blockchain.
Ghareeb Falazi, Uwe Breitenbücher, Florian Daniel, Andrea Lamparelli · 6 authors
No abstract is available for this record.
Han Liu, Dezhi Han, Dun Li
IoT devices have some special characteristics, such as mobility, limited performance, and distributed deployment, which makes it difficult for traditional centralized access control methods to support access control in current large-scale IoT environment. To address these challenges, this paper proposes an access control system in IoT named fabric-iot, which is based on Hyperledger Fabric blockchain framework and attributed based access control (ABAC). The system contains three kinds of smart contracts, which are Device Contract (DC), Policy Contract (PC), and Access Contract (AC). DC provides a method to store the URL of resource data produced by devices, and a method to query it. PC provides functions to manage ABAC policies for admin users. AC is the core program to implement an access control method for normal users. Combined with ABAC and blockchain technology, fabric-iot can provide decentralized, fine-grained and dynamic access control management in IoT. To verify the performance of this system, two groups of simulation experiments are designed. The results show that fabric-iot can maintain high throughput in large-scale request environment and reach consensus efficiently in a distributed system to ensure data consistency.
Komal Agrawal
With the advent of IoT, gadgets are now becoming more smart and independent. Truth is that the transformation towards the innovation is in progress yet there are still flaws, mainly in security areas like dependence on the data. Keeping in mind the advancement of IoT in the future, trusting in this vast approaching data source is of great importance. Blockchain is reached up to the position where it became the key innovation that will change the way we share data. Providing trust in conveyed situations, without using any advanced technical team is a development, which could change the way of working of numerous enterprises, the IoT amongst them. We can say with confidence that the concept of Blockchain, which is the technology behind crypto currency [3] Bitcoin [1], introduced a new era in the world of Internet and online services. In this paper, we will talk about develop a secure E-voting system using Blockchain technology where nobody can manipulate the votes and every user can vote only once. This is possible using the advantage of Ethereum smart contracts [2]. Smart contracts make it a powerful tool for the digitization of services in the Ethereum platform. Blockchain with smart contracts develops a safe, cheap, secure and transparent E-voting system. Ethereum and its network are suitable for it. Due to its consistency, large scale use and provision of smart contract logic. E-voting is an application that is possible using Blockchain technology with infused smart contracts. It needs to be digitalized over the Internet & that's what we will be working upon.
Vishal Baraiya, Seema Joshi
blockchain is decentralized immutable ledger technology maintaining integrity. So to conduct tamperproof election it’s one of the approach towards it. Smart contracts are Self executed code that is written on Ethereum platform in blockchain. An E-voting system should be completely secure and does not allow voting twice that is double spending in blockchain. So it should be completely transparent. In research work electronic voting application is implemented and tested using smart contract on Ethereum platform with the help of metamask wallet. The results of ballots and votes will be stored on Ethereum blockchain with the help of consensus algorithm proof of stake. This consensus is used in validating a transaction with concept of majority approval. Current electronic voting system requires a centralized authority to control the procedure from ballot input to result output and for monitoring of election. While blockchain technology provide decentralized system which is open across connected nodes. Blockchain assets provide increased level of system security from hacking and fraud. Every transaction in blockchain is time-stamped and signed digitally with the help of cryptographic algorithms, and it assigns unique hash value to every block so it can be trace easily. Blockchain technology is one of solutions because it embraces a decentralized system and the entire databases are owned by many users. The blockchain technology also has much vulnerability due to which many attacks like 51% attack, Double Spending attack, DDOS attack, Sybil attack, Eclipse attack and Routing attack can be performed on it.
Shengling Wang, Xidi Qu, Qin Hu, Xia Wang · 5 authors
Though voting-based consensus algorithms in blockchain outperform proof-based ones in energy- and transaction-efficiency, they are prone to incur wrong elections and bribery elections. The former originates from the uncertainties of candidates’ capability and availability, and the latter comes from the egoism of voters and candidates. Hence, in this paper, we propose an uncertainty- and collusion-proof voting consensus mechanism, including the selection pressure-based voting algorithm and the trustworthiness evaluation algorithm. The first algorithm can decrease the side effects of candidates’ uncertainties, lowering wrong elections while trading off the balance between efficiency and fairness in voting miners. The second algorithm adopts an incentive-compatible scoring rule to evaluate the trustworthiness of voting, motivating voters to report true beliefs on candidates by making egoism consistent with altruism so as to avoid bribery elections. A salient feature of our work is theoretically analyzing the proposed voting consensus mechanism by the large deviation theory. Our analysis provides not only the voting failure rate of a candidate but also its decay speed. The voting failure rate measures the incompetence of any candidate from a personal perspective by voting, based on which the concepts of the effective selection valve and the effective expectation of merit are introduced to help the system designer determine the optimal voting standard and guide a candidate to behave in an optimal way for lowering the voting failure rate.
Ahmet Kurt, Enes Erdin, Mumin Cebe, Kemal Akkaya · 5 authors
While various covert botnets were proposed in the past, they still lack complete anonymization for their servers/botmasters or suffer from slow communication between the botmaster and the bots. In this paper, we propose a new generation hybrid botnet that covertly and efficiently communicates over Bitcoin Lightning Network (LN), called LNBot. LN is a payment channel network operating on top of Bitcoin network for faster Bitcoin transactions with negligible fees. Exploiting various anonymity features of LN, we designed a scalable two-layer botnet which completely anonymize the identity of the botmaster. In the first layer, the botmaster sends commands anonymously to the C&C servers through LN transactions. Specifically, LNBot allows botmaster's commands to be sent in the form of surreptitious multihop LN payments, where the commands are encoded with ASCII or Huffman encoding to provide covert communications. In the second layer, C&C servers further relay those commands to the bots they control in their mini-botnets to launch any type of attacks to victim machines. We implemented a proof-of-concept on the actual LN and extensively analyzed the delay and cost performance of LNBot. Our analysis show that LNBot achieves better scalibility compared to the other similar blockchain botnets with negligible costs. Finally, we also provide and discuss a list of potential countermeasures to detect LNBot activities and minimize its impacts.
Ahmet Kurt, Enes Erdin, Mumin Cebe, Kemal Akkaya · 5 authors
No abstract is available for this record.
João Pereira dos Santos, Nuno Santos, David Dias
The proliferation of unreliable and biased information is a significant\nproblem on the Internet. To assess the credibility of the information retrieved\nfrom news websites and other sources, users often resort to social platforms\nlooking for confirmation with trustworthy parties. However, users may be faced\nwith considerable obstacles posed by the platform provider, who can prevent\naccess to certain content. This paper presents DClaims, a system that provides\na censorship-resistant distributed service for the exchange of information over\nthe Internet using web annotations. DClaims' fully decentralized architecture\nrelies on Inter-Planetary File System (IPFS) and Ethereum blockchain, both of\nwhich offer desirable censorship resistant properties. DClaims is implemented\nas a web annotations browser extension which allows for the classification of\nnews articles, on news websites. From our evaluation of the system, we conclude\nthat a large scale implementation of the system is practical and economically\nviable.\n
Do, Thuat, Thao Nguyen, Hung Pham
Consensus mechanism is the heart of any blockchain network. Many projects have proposed alternative protocols to improve restricted scalability of Proof of Work originated since Bitcoin. As an improvement of Delegated Proof of Stake, in this paper, we introduce a novel consensus, namely, Delegated Proof of Reputation, which is scalable, secure with an acceptable decentralization. Our innovative idea is replacing pure coinstaking by a reputation ranking system essentially based on ranking theories (PageRank, NCDawareRank and HodgeRank).
Utkarsh Saxena, J. S. Sodhi, Rajneesh Tanwar
The idea of smart home existed from 1970's onwards but has come into the knowledge of researchers and data scientist due to the development in the domain of internet of things (IoT) (Kopetz, 2011), but it still suffers from privacy and security vulnerabilities. Conventional security policies or approaches are not applicable to IoT, mainly due to its decentralised topology and the resource constraints of the majority of its devices (Dorri et al., 2017a). This Paper presents an innovative, novel and decentralised approach that can be used to augment the existing security architecture of a smart home network. Our scheme guarantees both trustworthiness and user privacy preservations.
Temidayo Abayomi-Zannu, Isaac Odun-Ayo, T. F. Barka
Abstract Voting is fundamental to any consensus-based society and is one of the most critical functions of democracy. Mobile voting (m-voting) was utilized as a means for voters to easily and conveniently cast their votes using their mobile devices which have been the most adopted means of communication but has a major problem which is safely securing the casted votes and avoiding any form of tampering. In this paper, we propose an m-voting framework that utilizes blockchain technology to securely store the casted votes and multi-factor authentication to authenticate the voters before they cast their votes while also providing an easily accessible, secure and transparent m-voting system.
Muntadher Sallal, Steve Schneider, Matthew Casey, Constantin Cătălin Drăgan · 9 authors
Online voting in the UK generally takes place without verifiability mechanisms, with providers that are trusted to provide ballot privacy and correctness of the result. However, replacing existing systems with verifiable voting systems with brand new algorithms and code presents a business risk to election providers. We present an approach for incremental change: adding a Selene-based verifiability layer to an existing online voting system. Selene is a verifiable e-voting protocol that publishes votes in plaintext alongside tracking numbers that enable voters to confirm that their votes have been captured correctly by the system. This results in a system where even the election authority running the system cannot change the result in an undetectable way. This gives stronger guarantees on the integrity of the election than were previously present. This gives an end-to-end verifiable system we call Verify My Vote (VMV). In addition, we outline how this approach supports further incremental changes towards the deployment of fully trustworthy online voting systems. The paper also describes the use of distributed ledger technology as a component of VMV to manage the verifiability data in a decentralised way for resilience and trust.
Oscar Avellaneda, Alan Bachmann, Abbie Barbir, Joni Brenan · 9 authors
The technology category now widely known as “decentralized identity” and more narrowly as “self-sovereign identity” didn’t even exist four years ago. At that time, the cutting edge of digital identity technology consisted of Internet- scale federated identity protocols such as OpenID Connect and user-centric data sharing protocols such as User-Managed Access (UMA). Then along came Bitcoin and a surge of interest in blockchain and distributed ledger technology (DLT). Although the initial uses of this technology focused primarily on cryptocurrency, it didn’t take long for the digital identity community to begin applying it to digital identity scenarios.
Authors unavailable
Election is a significant job in our Elective Government. As technology progress with upcoming days, its impact becomes more optimistic. One such outcome is the Blockchain. It is possible to transform the process of voting system due to its decentralized property of immutability. Voting in most places are non-transparent and common with the corruption. In this paper we proposed the technology, is Blockchain technology. The concept of this paper is to develop a decentralized application for voting system. From there, the transaction votes are stored in the blockchain could be illustrated by the examining the block hashes. The outcome of the project shows the transaction of tokens from voter’s wallet into the candidate’s wallet. This application can deploy on a test platform using the Ethereum Virtual Machine (EVM) it provides the network to test the application. From there, the integrity of the blockchain technology is illustrated.
Markus Knecht
Smart contracts on a blockchain behave precisely as specified by their code. A vulnerability in this code can lead to unexpected behaviour, which is hard to fix because a blockchain does not allow to change smart contract code after its deployment. Such vulnerabilities have led to several incidents. In the aftermath of such an event, a hard-fork between Ethereum and Ethereum classic was the result. This thesis proposes to develop a new smart contract programming language with the primary focus on safety, auditability, and the intention to prevent as many of the known categories of vulnerabilities by design as possible. The programming language's code is validated during deployment and afterwards isolated from other smart contracts running on the same blockchain to enforce compile-time guarantees during runtime. The designed programming language does evaluate new concepts and paradigms rarely used in non-smart contract environments for their potential benefit in a smart contract environment.