In the Bitcoin blockchain, rewarding methods for remunerating miners participating in a pool have to meet certain requirements in order to guarantee the proper functioning of the cryptocurrency ecosystem. In particular, these allocation rules reward pool participants in proportion to their contribution in the transaction validation process. Deployed rewarding methods met fairness concerns at the expense of vulnerability to miners exploiting pools' attractiveness for deciding when to mine for a pool and when to `hop' to another one resulting more attractive: a phenomenon called pool-hopping. The most used score-based methods are designed to prevent this practice, but are not completely hopping proof. In this work, we propose a methodology to analyze the pool-hopping phenomenon, focusing on the detection of pool-hoppers. Analyzing those Bitcoin transactions that pools create for rewarding its participants, it is possible to determine time epochs where miners worked. Thus, we analyze those miners that have worked intermittently for pools adopting a rewarding system which pays out for each validated block. This evaluation leads us qualifying the miners that have hopped along with their hopping behavior and financial performance.
One of the ways in which a city can become smarter is to grow a local economy around the sharing of data from IoT devices and other open data that can be used in applications to improve the lives of its citizens. Prior work and ongoing projects have examined or are currently focused on the development of centralized data marketplaces for smart cities. Here we explore how a decentralized data marketplace could be created using blockchain and other distributed ledger technologies. We consider the possible benefits of such a decentralized architecture, identify different elements that such a decentralized marketplace should have, and show how they could be potentially integrated into a comprehensive solution. We also present a simple smart contract implementation of a decentralized registry where data products can be posted by data owners for retrieval by potential buyers.
Shaohan Feng, Wenbo Wang, Dusit Niyato, Dong In Kim · 5 authors
With the explosive growth of smart IoT devices at the edge of the Internet, embedding sensors on mobile devices for massive data collection and collective environment sensing has been envisioned as a cost-effective solution for IoT applications. However, existing IoT platforms and framework rely on dedicated middleware for (semi-) centralized task dispatching, data storage and incentive provision. Consequently, they are usually expensive to deploy, have limited adaptability to diverse requirements, and face a series of data security and privacy issues. In this paper, we employ permissionless blockchains to construct a purely decentralized platform for data storage and trading in a wireless-powered IoT crowdsensing system. In the system, IoT sensors use the power wirelessly transferred from RF-energy beacons for data sensing and transmission to an access point. The data is then forwarded to the blockchain for distributed ledger services, i.e., data/transaction verification, recording, and maintenance. Due to the coupled interference of wireless transmission and the transaction fee incurred by the blockchain's distributed ledger services, rational sensors have to decide on their transmission rates to maximize their individual payoff. Thus, we formulate a noncooperative game model to analyze this competitive situation among the sensors. We provide the analytical condition for the existence of the Nash equilibria as well as a series of insightful numerical results about the equilibrium strategies in the game.
Blockchain is a decentralized technology. It has extensive power to solve business problems. Cryptography secures the records in a blockchain transaction and each transaction is tied to previous transactions or records. Blockchain transactions are validated by algorithms on the nodes. A single entity cannot create a transaction. Finally, blockchains provide transparency, giving each participant the ability to monitor the transactions at any time. Smart contract make secure transaction which helps to avoid third party disruption. Ethereum is a decentralized platform that runs smart contracts. This enables developers to create markets move funds in accordance with instructions given long in the past. The main features of blockchain are Decentralization, Immutability Faster dealings, Transaction and validation happens in seconds etc..
John Collomosse, Tu Bui, Alan Brown, John Sheridan · 9 authors
We present ARCHANGEL; a decentralised platform for ensuring the long-term integrity of digital documents stored within public archives. Document integrity is fundamental to public trust in archives. Yet currently that trust is built upon institutional reputation --- trust at face value in a centralised authority, like a national government archive or University. ARCHANGEL proposes a shift to a technological underscoring of that trust, using distributed ledger technology (DLT) to cryptographically guarantee the provenance, immutability and so the integrity of archived documents. We describe the ARCHANGEL architecture, and report on a prototype of that architecture build over the Ethereum infrastructure. We report early evaluation and feedback of ARCHANGEL from stakeholders in the research data archives space.
Pietro Tedeschi, Giuseppe Piro, Jose Antonio Sanchez Murillo, Nemanja Ignjatov · 7 authors
Blockchain is emerging as a promising technology that is able to support transparent, secure, and immutable transactions traceability in decentralized networks. Its usage in many application domains, including the Internet of Things, is gaining the attention of even more researchers and industries worldwide. In line with current research interests, the work presented in this letter has been carried out in the context of the European H2020 symbIoTe project. Among its main features, the symbIoTe framework offers bartering functionalities across a federation of Internet of Things platforms. This letter extends the baseline implementation of bartering functionalities and formulates a novel methodology that properly integrates and takes advantages from the Blockchain technology. Even if the proposed approach is general, the main facets characterizing the conceived approach are illustrated through a fictional use case envisaging the provisioning of Intelligent Transportation System and air pollution services in a Smart City.
Dimitris Chatzopoulos, Sujit Gujar, Boi Faltings, Pan Hui
The popularity and applicability of mobile crowdsensing applications are continuously increasing due to the widespread of mobile devices and their sensing and processing capabilities. However, we need to offer appropriate incentives to the mobile users who contribute their resources and preserve their privacy. Blockchain technologies enable semi-anonymous multi-party interactions and can be utilized in crowdsensing applications to maintain the privacy of the mobile users while ensuring first-rate crowdsensed data. In this work, we propose to use blockchain technologies and smart contracts to orchestrate the interactions between mobile crowdsensing providers and mobile users for the case of spatial crowdsensing, where mobile users need to be at specific locations to perform the tasks. Smart contracts, by operating as processes that are executed on the blockchain, are used to preserve users' privacy and make payments. Furthermore, for the assignment of the crowdsensing tasks to the mobile users, we design a truthful, cost-optimal auction that minimizes the payments from the crowdsensing providers to the mobile users. Extensive experimental results show that the proposed privacy preserving auction outperforms state-of-the-art proposals regarding cost by ten times for high numbers of mobile users and tasks.
In proof-of-stake based consortium blockchain networks, pre-selected miners compete to solve a crypto-puzzle with a successfully mining probability proportional to the amount of their stakes. When the puzzle is solved, the miners are encouraged to take part in mined block propagation for verification to win a transaction fee from the blockchain user. The mined block should be propagated over wired or wireless networks, and be verified as quickly as possible to decrease consensus propagation delay. In this letter, we study incentivizing the consensus propagation considering the tradeoff between the network delay of block propagation process and offered transaction fee from the blockchain user. A Stackelberg game is then formulated to jointly maximize utility of the blockchain user and individual profit of the miners. The blockchain user acting as the leader sets the transaction fee for block verification. The miners acting as the followers decide on the number of recruited verifiers over wired or wireless networks. We apply the backward induction to analyze the existence and uniqueness of the Stackelberg equilibrium. Performance evaluation validates the feasibility and efficiency of the proposed game model in consensus propagation.
The redesign of cloud storage with the amalgamation of cooperative cloud and an immutable and unhackable distributed database blockchain thrives towards a strong CIA triad and secured data provenance. The conspiracy ideology associated with the traditional cloud has economized with cooperative cloud storage like Storj and Sia, decentralized storage, which allows renting the unused hard drive space and getting monetary compensation in an exchange with cryptocurrency. In this article, the authors explain how confidentiality, integrity and availability can be progressed with cooperative cloud storage along with tamper-proof data provenance management with ethereum smart contracts using zero-knowledge proof (ZKP). A contemporary architecture is proposed with regards to storing data on the cooperative cloud and collecting and verifying the provenance data from the cloud and publishing the provenance data into blockchain network as transactions.
This article surveys blockchain-based approaches for several security services. These services include authentication, confidentiality, privacy, and access control list (ACL), data and resource provenance, and integrity assurance. All these services are critical for the current distributed applications, especially due to the large amount of data being processed over the networks and the use of cloud computing. Authentication ensures that the user is who he/she claims to be. Confidentiality guarantees that data cannot be read by unauthorized users. Privacy provides the users the ability to control who can access their data. Provenance allows an efficient tracking of the data and resources along with their ownership and utilization over the network. Integrity helps in verifying that the data has not been modified or altered. These services are currently managed by centralized controllers, for example, a certificate authority. Therefore, the services are prone to attacks on the centralized controller. On the other hand, blockchain is a secured and distributed ledger that can help resolve many of the problems with centralization. The objectives of this paper are to give insights on the use of security services for current applications, to highlight the state of the art techniques that are currently used to provide these services, to describe their challenges, and to discuss how the blockchain technology can resolve these challenges. Further, several blockchain-based approaches providing such security services are compared thoroughly. Challenges associated with using blockchain-based security services are also discussed to spur further research in this area.
Blockchain brings a peer-to-peer transaction solution without a trusted third authority over the peer-to-peer network. Proof-of-work (PoW), also called `mining', incents some peers (called miners)to compete for the right of block generation by rewarding a certain mount of cryptocurrency. Hence, PoW undertakes the cryptocurrency creation and block generation in a blockchain based transaction system (BTS). However, in a BTS, the block mining reward (BMR)will be terminated after that the regulated quantity of currency have been minted. Although the voluntarily paid transaction fee is allowed to support BMR, the stable reward for block mining is no longer guaranteed, and which inevitably destroys the sustainability of BTS. In this work, we propose a sustainable reward mechanism (SRM)for block mining in BTS. Specifically, SRM introduces a mandatory transaction fee mechanism with dedicated fee rate determination algorithm. An on-chain public account (PA), which is trust-free but security-provable, is set to collect the dynamic transaction fees. With transaction fee collection under adaptive fee rate setting, PA provides the steady BMR, thus makes blockchain sustainable when the currency creation purposed BMR has been terminated. Numerical results are presented to demonstrate the effectiveness of SRM.
As technology advances, many countries have now opted for electronic voting systems. Any voting system must follow principles of transparency and impartiality in order to achieve fairness; the electronic voting process must also be protected against cyberattacks or denial-of-service attacks (DDOS) because such attacks may affect the processing time in voting procedures and even hinder the fairness in voting. This study establishes a network security mechanism for voting systems based on blockchain technology. The blockchain mechanism employs a distributed architecture that can prevent system shutdown resulting from malicious cyberattacks; additionally, any user in the blockchain can authenticate data integrity, which satisfies requirements of transparency and impartiality in voting systems. This study utilizes bilinear pairing to establish network security in voting systems, which call for anonymity, authenticity, integrity, and non-repudiation. When authenticating voting integrity, the user's anonymity must be ensured to prevent identity revelation, and the data must be protected against malicious tampering such security measures also fulfill blockchain requirements. The proposed voting system relies on the basis of blockchains to create a trustworthy voting system. In current blockchain technology, smart contracts allow the establishment of voter-related regulations to prevent controversies during voting processes. Additionally, in order to establish both a secret ballot and an open ballot system, the study also implements a bilinear pairing security mechanism to ensure the overall security of a voting procedure.
Crowd-sensing systems have gained considerable interests and adoption in recent years. However, most existing crowd-sensing systems rely on central servers, which are subject to low reliability due to the traditional centralized architecture and high service fee. Motivated by constructing a crowd-sensing system with security and low service fee, we propose a blockchain-based crowd-sensing system (BCS), which replaces traditional triangle architecture by decentralized blockchain system. Also, in order to accelerate the formation of the fabric of trust, BCS implements applications of smart contracts to reward sensing-task workers, which offers reliable anonymity in the meantime. By leveraging blockchain technology, BCS has good performance in privacy protection and system robustness.
Nick Hynes, David Dao, David Yan, Raymond Cheng · 5 authors
In this work, we demonstrate Sterling, a decentralized marketplace for private data. Sterling enables privacy-preserving distribution and use of data by using privacy-preserving smart contracts which run on a permissionless blockchain. The privacy-preserving smart contracts, written by data providers and consumers, immutably and irrevocably represent the interests of their creators. In particular, we provide a mechanism for data providers to control the use of their data through automatic verification of data consumer contracts, allowing providers to express constraints such as pricing and differential privacy. Through smart contracts and trusted execution environments, Sterling enables privacy-preserving analytics and machine learning over private data in an efficient manner. The resulting economy ensures that the interests of all parties are aligned. For the demonstration, we highlight the use of Sterling for training machine learning models on individuals' health data. In doing so, we showcase novel approaches to automatically appraising training data, verifying and enforcing model privacy properties, and efficiently training private models on the blockchain using trusted hardware.
The blockchain systems are analyzed under the context of the personal health record system (PHRs) requirements. The transparent property of blockchain may cause the privacy and confidentiality concerns for PHRs. The append-only storage of blockchain can be a barrier for implementing the revocability of consent in PHRs. Moreover, the health care data can be very large exceeding the practical storage capabilities of the current blockchain usages. The most important issues of blockchain include the limited storage, privacy, consent revocation, performance, energy consumption and scalability. A blockchain based secret-data sharing model is proposed by using a proxy re-encryption technique to support the PHRs in this work. Some potential attacks which can attempt on the proposed model and how the model can handle such attempts is also discussed.
Aug 1, 2018·2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE)
Paul Sarda, Mohammad Jabed Morshed Chowdhury, Alan Colman, Muhammad Ashad Kabir · 5 authors
Current job recruitment process involves a good number of documentations. It is not uncommon for job applicants to misrepresent, overstate or falsify past employment, specifically work experience, and skills. Where this occurs and the applicant is subsequently appointed, a company may be exposed to significant commercial and legal risk. Companies usually employ third party HR recruitment agencies to verify the authenticity of an applicant's listed work experience. However, verification of applicant's past work experience is both time consuming and costly. Moreover, companies have to rely on the third parties, which may not be trustworthy. Therefore, small and medium size companies usually avoid the verification process. In this research, we demonstrate how blockchain technology can provide cost-effective, and real-time work history verification. The proposed approach also ensures trustworthy and privacy-preserving (work-history) data sharing. Furthermore, we have implemented a prototype to demonstrate how individuals can share and verify work history using Ethereum-based public blockchain.
Andrea Tesei, Luca Di Mauro, M. Falcitelli, Sandro Noto · 5 authors
Intelligent Transport Systems (ITS) show many potential benefits to the way we travel today. The security requirements to be matched in this kind of systems are challenging and they show technical, societal, legal, and economical concerns (e.g. anonymity, accountability, non-repudiation). To address security, standardization bodies (IEEE 1609.2, ETSI) and harmonization efforts (Car2Car Communication Consortium (C2C-CC)) have proposed a Certification Authority-based (CA-based) Vehicular Public Key Infrastructure (VPKI) which still suffers of Single Point of Failure (SPoF) locate in CAs and does not provide transparency in the certificate issuance. We propose IOTA-VPKI, a Distributed Ledger Technology-based (DLT-based) VPKI that improve the state-of-the-art eliminating SPoF with seamless scalability with respect to the users. IOTA-VPKI also guarantees transparency in the issuance of certificates as well as historical proof-of-possession by storing signed and hashed certificates on the IOTA ledger to facilitate verification procedure. The use of IOTA DLT assure also the feasible deploy in Internet of Things (IoT) domain, where the devices involved have limited computational resources. The effectiveness of our DLT-based VPKI will be measured in testbed for EU Horizon 2020-funded AUTOmated driving Progressed by Internet Of Things (AUTOPILOT) project.
With the development of computer and network technology, on-board computers have more stronger capability of computing and network communication. Multiple vehicles can form an Autonomous Vehicular Cloud (AVC) for the certain need to provide cloud computing services for customers. However, the infrastructure of AVC is open completely, how to guarantee the non-repudiation of task execution information is a very important issue during the process of task execution. Blockchain technology is a proven technology with information security and non-repudiation in distributed environments. Smart contract of Ethereum used to design a kind of task scheduling strategy which is suitable for the AVC environment in this paper. The strategy can guarantee the non-repudiation of task execution information. This paper builds the private chain of Ethereum on simulation vehicles node and creates and deploys the smart contract. Experiments show that the task scheduling strategy is very effective.
A trusted electronic election system requires that all the involved information must go public. However, it focuses not only on transparency but also on privacy issues. In other words, each ballot should be counted anonymously, correctly, and efficiently. In this work, an effective e-voting system is proposed for voters to minimize their trust in the authority or government. We ensure the transparency of election by putting all messages on the Ethereum blockchain; in the meantime, the privacy of individual voter is protected via an effective ring signature mechanism. Besides, the attractive self-tallying feature is also built in our system, which guarantees that everyone who can access the blockchain network is able to tally the result on his own, i.e., no third party is required after the voting phase. More importantly, we ensure the correctness of voting results and keep the Ethereum gas cost of individual participant as low as possible, at the same time. Moreover, the pre-described characteristics of stealth address in our system makes it more suitable for large-scale election on line.
Aug 1, 2018·2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE)
Mohammad Jabed Morshed Chowdhury, Alan Colman, Muhammad Ashad Kabir, Jun Han · 5 authors
Personal data such as electronic medical records and academic records are critical and sensitive private information. These personal information is usually hosted across many data-custodian systems. Personal Data Store (PDS) is a service that lets an individual store, manage and deploy their key personal data in a highly secure and structured way. It also gives the user a central point of control for their personal information. One of the inherent problems of digital records is that it can be easily forged. Therefore, the data-consumer(with whom the data is shared) often needs to verify the authenticity of the shared document/record by communicating with the document/certificate issuing authority (e.g., data custodian). However, this process is time consuming and inefficient. In recent time, blockchain has gained tremendous attention from both industry and academia for distributed recording and immutable transactions. Blockchain provides a shared, immutable and transparent history of transactions enabling the building of applications that incorporate trust, accountability and transparency. This provides a unique opportunity to develop a secure and trustable data sharing system using blockchain. However, blockchain is primarily proposed for publicly verifiable transactions and does not provide privacy to the individuals. In this paper, we propose a data sharing framework that will guarantee the authenticity of the shared data in real-time and provide transactional privacy in a blockchain network. We have implemented our framework in a prototype that ensures privacy, integrity, and fine-grained access control over the shared data. The proposed work can significantly reduce the turnaround time for data sharing, improve the decision making process and reduce the overall cost.
Nasr Al-Zaben, Md. Mehedi Hassan Onik, Jinhong Yang, Nam Yong Lee · 5 authors
Surveillance and secrecy breaching incidents of users' privacy questioned the current third-parties data collection procedure. Massive amounts of Personally Identifiable Information (PII) are being exploited due to malpractice, identity theft, spamming, phishing and cyber-espionage. A large amount of data flow from users to enterprises for data-driven market analysis and prediction. Consequently, it is tough to track the flow and genuineness of PII. Blockchain technology, an ‘immutable’ distributed ledger which can efficaciously track PII exchange, store, and distribution. In contrast, ongoing EU General Data Protection Regulation (GDPR) demands ‘right to forget’ and ‘should be erasable’ rights. However, this paper proposes an off-chain Blockchain architecture which uses both local database and distributed ledgers to preserve a trustable PII life cycle. Considering the key factors of GDPR, prevailing Blockchain architecture were modified and a prototype was created to validate our proposed architecture using multichain 2.0. Proposed architecture stores PII and Non-PII physically separated location. Finally, with proposed architecture user will realm privacy and rigidity of Blockchain along with the privacy regulation of GDPR. Validation is done by comparing proposed system with existing methodology from technical aspects, future research scopes is also well advocated.
Simon Lebech Cichosz, Mads Nibe Stausholm, Thomas Kronborg, Peter Vestergaard · 5 authors
INTRODUCTION: Patients with diabetes often generate large amounts of data specifically related to the disease and to their general health. Cross-institutional sharing of patient health care data is complex, and as a consequence, data are not always available to the health care provider treating the patient. Accommodating this challenge could lead to better clinical effectiveness and improve clinical research. This work aims to present an approach for a blockchain-based platform for sharing health care data. The approach considers privacy concerns, data sharing, and patients as the center for governing their own data. METHODS: The concept of this blockchain-based platform consists of using the NEM multi-signature blockchain contracts for access control of data management and the sharing and encryption of data to allow privacy and control of health care data. The architecture is built around cryptography, tokens, and multi-signature contracts. The multi-signature contract enables several entities to administrate the activity of an account and control the assets of one account. Multi-signature generates a contract that assigns the rights and powers of a certain account to other accounts; this contract can be edited to allow or remove entities. DISCUSSION: Using blockchain could lead to improvements in diabetes data management. In the coming years, this technology should be implemented in existing small-scale diabetes health care system to explore its real-world benefits and challenges. CONCLUSION: This new approach could potentially lead to more efficient sharing of data between institutions and utilization of new types of data and research possibilities.
One of the main issues in digital forensics is the management of evidences. From the time of evidence collection until the time of their exploitation in a legal court, evidences may be accessed by multiple parties involved in the investigation that take temporary their ownership. This process, called Chain of Custody (CoC), must ensure that evidences are not altered during the investigation, despite multiple entities owned them, in order to be admissible in a legal court. Currently digital evidences CoC is managed entirely manually with entities involved in the chain required to fill in documents accompanying the evidence. In this paper, we propose a Blockchain-based Chain of Custody (B-CoC) to dematerialize the CoC process guaranteeing auditable integrity of the collected evidences and traceability of owners. We developed a prototype of B-CoC based on Ethereum and we evaluated its performance.