Blockchain Papers

Baokun Zheng, Liehuang Zhu, Meng Shen, Feng Gao · 7 authors

No abstract is available for this record.

Jian Liu, Wenting Li, Ghassan Karame, N. Asokan

Motivated by the great success and adoption of Bitcoin, a number of cryptocurrencies such as Litecoin, Dogecoin, and Ethereum are becoming increasingly popular. Although existing blockchain-based cryptocurrency schemes can ensure reasonable security for transactions, they do not consider any notion of fairness. Fair exchange allows two players to exchange digital “items,” such as digital signatures, over insecure networks fairly, so that either each player gets the other's item, or neither player does. Given that blockchain participants typically do not trust each other, enabling fairness in existing cryptocurrencies is an essential but insufficiently explored problem. In this article, we explore the solution space for enabling the fair exchange of a cryptocurrency payment for a receipt. We identify the timeliness of an exchange as an important property especially when one of the parties involved in the exchange is resource-constrained. We introduce the notion of strong timeliness for a fair exchange protocol and propose two fair payment-for-receipt protocol instantiations that leverage functionality of the blockchain to achieve strong timeliness. We implement both and compare their security and efficiency.

Kevin Liu, Harsh Desai, Lalana Kagal, Murat Kantarcıoğlu

As more and more data is collected for various reasons, the sharing of such data becomes paramount to increasing its value. Many applications ranging from smart cities to personalized health care require individuals and organizations to share data at an unprecedented scale. Data sharing is crucial in today's world, but due to privacy reasons, security concerns and regulation issues, the conditions under which the sharing occurs needs to be carefully specified. Currently, this process is done by lawyers and requires the costly signing of legal agreements. In many cases, these data sharing agreements are hard to track, manage or enforce. In this work, we propose a novel alternative for tracking, managing and especially enforcing such data sharing agreements using smart contracts and blockchain technology. We design a framework that generates smart contracts from parameters based on legal data sharing agreements. The terms in these agreements are automatically enforced by the system. Monetary punishment can be employed using secure voting by external auditors to hold the violators accountable. Our experimental evaluation shows that our proposed framework is efficient and low-cost.

John Collomosse, Tu Bui, Alan Brown, John Sheridan · 9 authors

We present ARCHANGEL; a de-centralised 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.

Wei-Jr Lai, Ja‐Ling Wu

A trusted electronic election system requires that all the involved information must go public, that is, it focuses not only on transparency but also privacy issues. In other words, each ballot should be counted anonymously, correctly, and efficiently. In this work, a lightweight 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 message on the Ethereum blockchain, in the meantime, the privacy of individual voter is protected via an efficient and 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, no third party is required after 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. Clearly, the pre-described characteristics make our system more suitable for large-scale election.

Jong Sou Park, Young Sik Kim, Chang-hak Choi, JangSup Shim

Many interesting news and activities are going on in the field of blockchain (sometimes called, Distributed Ledger Technology) related technologies like cryptocurrency, Initial Coin Offering (ICO), Internet of Things (IoT), Big Data, Artificial Intelligence (AI, mostly Deep Learning). Not only developing countries but also developed countries need to be concerned about applying blockchain technology to their e-government system. Blockchain technology has brought a very deep innovation over conventional Client Server Trusted Third Party intermediary system to pure peer-to-peer (P2P) based smart contract system. This smart contract based peer-to-peer system allow participants to share data which was not possible under Client Server Trusted Third Party system due to architectural monopoly nature of Client Server. Smart contract concept brought logical conditions to share data among participants but it does not provide any definition about data value. This peer-to-peer based data sharing can be practically possible only under definition of value on data shared. If this definition is vague, then it will be very difficult to share data among participants. Also if this definition is clear, data sharing participants can get much benefit from this data sharing. This data sharing will be only effective from blockchain based architecture.

Arman Pouraghily, Md Nazmul Islam, Sandip Kundu, Tilman Wolf

Over past two decades, the idea of Internet of Things has been adopted widely as a solution to many societal problems in different areas. These areas include but are not limited to healthcare, transportation, environment, etc. Low cost overhead of Internet connectivity feature has been the main contributing factor in the widespread use of such devices in building different IoT solutions. The original stovepipe architecture of IoT systems limits the possibility of sharing the hardware infrastructure of IoT solutions and therefore is the main barrier against novel solutions. In recent year, however, there have been efforts to come up with solutions for sharing the hardware infrastructure and therefore pave the way for innovative solutions by amortizing the capital cost of setting up the hardware. In this work, we propose an architectural guideline for blockchain enabled IoT devices which facilitates sharing them between multiple blockchain ecosystems and at the same time, ensures the exclusive access to them seamlessly through blockchain smart contracts.

Fabrice Benhamouda, Shai Halevi, Tzipora Halevi

Hyperledger Fabric is a "permissioned" blockchain architecture, providing a consistent distributed ledger, shared by a set of "peers." As with every blockchain architecture, the core principle of Hyperledger Fabric is that all the peers must have the same view of the shared ledger, making it challenging to support private data for the different peers. Extending Hyperledger Fabric to support private data (that can influence transactions) would open the door to many exciting new applications, in areas from healthcare to commerce, insurance, finance, and more. In this work we explored adding private-data support to Hyperledger Fabric using secure multiparty computation (MPC). Specifically, in our solution the peers store on the chain encryption of their private data, and use secure MPC whenever such private data is needed in a transaction. This solution is very general, allowing in principle to base transactions on any combination of public and private data. We created a demo of our solution over Hyperledger Fabric v1.0, implementing a bidding system where sellers can list assets on the ledger with a secret reserve price, and bidders publish their bids on the ledger but keep secret the bidding price itself. We implemented a smart contract (aka "chaincode") that runs the auction on this secret data, using a simple secure-MPC protocol that was built using the EMP-toolkit library. The chaincode itself was written in Go, and we used the SWIG library to make it possible to call our protocol implementation in C++. We identified two basic services that should be added to Hyperledger Fabric to support our solution, and are now working on implementing them.

Michael Grabatin, Wolfgang Hommel

In identity federations, users assigned to identity providers (IDPs) can access applications operated by service providers (SPs) without SP-specific credentials for authentication and authorization. While OpenID Connect and SAML are the two most widely adopted federation standards, using them inherently results in a trade-off between data quality guarantees and scalability, given how they handle the Metadata about the involved IDPs and SPs. This paper presents a novel approach for federation membership and federation Metadata management based on Distributed Ledger Technology. It applies the core idea of Certificate Transparency, as known from Global-PKI certificate authorities for X.509v3 server certificates, to SAML federation Metadata; therefore, it achieves OpenID Connect's federation building flexibility without losing the significant advantages of traditional SAML federations. An implementation based on Hyperledger Fabric is used to evaluate typical use cases by measuring impacts on Metadata distribution latency and Metadata size, and to discuss the feasibility of the presented approach.

Shengshan Hu, Chengjun Cai, Qian Wang, Cong Wang · 6 authors

Enabling search directly over encrypted data is a desirable technique to allow users to effectively utilize encrypted data outsourced to a remote server like cloud service provider. So far, most existing solutions focus on an honest-but-curious server, while security designs against a malicious server have not drawn enough attention. It is not until recently that a few works address the issue of verifiable designs that enable the data owner to verify the integrity of search results. Unfortunately, these verification mechanisms are highly dependent on the specific encrypted search index structures, and fail to support complex queries. There is a lack of a general verification mechanism that can be applied to all search schemes. Moreover, no effective countermeasures (e.g., punishing the cheater) are available when an unfaithful server is detected. In this work, we explore the potential of smart contract in Ethereum, an emerging blockchain-based decentralized technology that provides a new paradigm for trusted and transparent computing. By replacing the central server with a carefully-designed smart contract, we construct a decentralized privacy-preserving search scheme where the data owner can receive correct search results with assurance and without worrying about potential wrongdoings of a malicious server. To better support practical applications, we introduce fairness to our scheme by designing a new smart contract for a financially-fair search construction, in which every participant (especially in the multiuser setting) is treated equally and incentivized to conform to correct computations. In this way, an honest party can always gain what he deserves while a malicious one gets nothing. Finally, we implement a prototype of our construction and deploy it to a locally simulated network and an official Ethereum test network, respectively. The extensive experiments and evaluations demonstrate the practicability of our decentralized search scheme over encrypted data.

Stephen Kirkman, Richard E. Newman

An outdated Service Level Agreement (SLA) model, untrusted third parties with access to our data, unknown data location, and unwanted data movement continue to negatively affect trust in the cloud. The majority of current research into cloud trust focuses on ensuring a trustworthy hardware platform using attestations verified by some trusted third party(TTP). We are proposing an approach to improve cloud trust that leverages blockchain technology to help reduce the problem of depending on TTPs for policy evaluation and storage and help track our data. It provides consumers more control and expression of how they want their data handled and by whom. We propose to use Ethereum blockchain for storage and smart contracts as the vehicle for the policies. The main contributions presented in this research are: 1) storing policies in an authoritative source outside the cloud, 2) improving cloud trust by using decentralization, 3) providing a data movement policy model.

Vaso Rahimzadeh

Clinical research and health information data sharing are but ripples in a growing wave of reimagined applications of distributed ledger technologies beyond the digital marketplace for which they were originally created. This paper explores the use of distributed ledger technologies to facilitate single institutional ethics review of multi-site, collaborative studies in the dataintensive sciences such as genetics and genomics. Immutable record-keeping, automatable protocol amendments and direct connectivity between stakeholders in the research enterprise (e.g., researchers, research ethics committees, institutions, funders and regulators) comprise several of the conceptual and technological advantages of distributed ledger technologies to research ethics review. This novel-use proposal dovetails recent policy reforms to research ethics review across North America that mandate a single ethics review for any study that takes place across more than one research site. Such reforms in the United States, Canada and Australia replace prior institution-by-institution approval mechanisms that contributed to significant research delays and duplicative procedures for collaborative research worldwide. While this paper centers on the Common Rule revision in the United States, the single ethics review mandate is a noteworthy example of regulation evolving in parallel with advances in the dataintensive sciences it governs. The informational exchange capacities of distributed ledger technologies align well with the procedural goals of streamlining the ethics review system under the new Common Rule ahead of its official implementation on January 19, 2020. The ethical, legal and social implications of applying such technologies to ethics review will be explored in this concept paper. Namely, the paper proposes how administrative data from research ethics committees (REC) could be protected and shared responsibly, as well as interinstitutional cooperation negotiated within a centralized network of research ethics committees using the blockchain. Keywords: Blockchain, Data Sharing, Ethics Review, Governance, IRB, Research, Single Mutual Recognition

Peng Jiang, Fuchun Guo, Willy Susilo, Man Ho Au · 6 authors

A procurement protocol is a protocol for a buyer to purchase digital goods at their prices from a vendor. A procurement protocol with privacy preservation can be achieved by priced oblivious transfer (POT). POT allows the buyer to obliviously procure items one by one. An adaptive POT protocol only consumes O(1) communication cost in each transaction, where all items are committed and encrypted before transactions. However, we found that the state-of-the-art adaptive POT protocol proposed by Rial et al. is less practical and does not meet real-world needs. It has to restrict to the one-buyer setting where all items are encrypted associated with one buyer's public key. For multiple buyers, the vendor must respectively encrypt all the same items for each buyer. Besides, it has to employ computationally expensive primitives such as zero-knowledge proof which imply inefficient computation operations. It is therefore unscalable and unsuitable in large-scale applications. In this paper, we propose an efficient adaptive priced oblivious transfer protocol to address the aforementioned problems. The proposed adaptive POT is built on top of a new cryptographic primitive, namely, adaptive set membership encryption (ASME). In our proposed protocol, all items are encrypted without the use of buyers' public keys and hence they can be used for universal buyers. Our protocol significantly reduces the transaction cost compared to existing schemes. For example, the communication in each transaction costs only 6 group elements compared to at least 141 group elements in Rial et al.'s protocol. The implementation shows that our protocol is efficient in terms of bandwidth and computational cost.

Olivia Choudhury, Hillol Sarker, Nolan Rudolph, Morgan A. Foreman · 9 authors

Recent changes to the Common Rule, which govern Institutional Review Boards (IRB), require implementing new policies to strengthen research protocols involving human subjects. A major challenge in implementing such policies is an inability to automatically and consistently meet these ethical rules while securing sensitive information collected during the study. In this paper, we propose a novel framework, based on blockchain technology, to enforce IRB regulations on data collection. We demonstrate how to design smart contracts and a ledger to meet the requirements of an IRB protocol, including subject recruitment, informed consent management, secondary data sharing, monitoring risks, and generating automated assessments for continuous review. Furthermore, we show how we can employ the immutable transaction log in the blockchain to embed security in research activities by detecting malicious activities and robustly tracking subject involvement. We evaluate our approach by assessing its ability to enforce IRB guidelines in different types of human subjects studies, including a genomic study, a drug trial, and a wearable sensor monitoring study. Keywords: Blockchain, Data Sharing, Data Exchange, EHR, electronic health record, Ethereum, interplanetary filesystem, IPFS

Jiayu Zhou, Fengyi Tang, He Zhu, Ning Nan · 5 authors

Recent advances in blockchain technologies have provided exciting opportunities for decentralized applications. Specifically, blockchain-based smart contracts enable credible transactions without authorized third parties. The attractive properties of smart contracts facilitate distributed data vending, allowing for proprietary data to be securely exchanged on a blockchain. Distributed data vending can transform domains such as healthcare by encouraging data distribution from owners and enabling large-scale data aggregation. However, one key challenge in distributed data vending is the trade-off dilemma between the effectiveness of data retrieval, and the leakage risk from indexing the data. In this paper, we propose a framework for distributed data vending through a combination of data embedding and similarity learning. We illustrate our framework through a practical scenario of distributing and aggregating electronic medical records on a blockchain. Extensive empirical results demonstrate the effectiveness of our framework.

Indrachapa Bandara, Florin Ioraş, M.P. Arraiza

The network-centric world of the 21st century and explosive growth of the internet related technologies brought modern cybersecurity culture with complex threat landscape in the Higher Education environment. Cybersecurity landscape is always changing and education providers often do not have remit or in fact the means and capacity to cover the range of activities learners engage with, which attest their achievements, knowledge, and skills. Currently the awarding and validation of qualifications occurs exclusively under centralised management of an education institution or an employer take more ownership of the learning experience and its outcomes without compromising on safety, security, and accessibility. The centralised model of the present awarding and validation is no longer sustainable because learning happens increasingly on online platforms, and learning is far more international than it used to be. Key higher educational providers introduced degree apprenticeships which are new way to ‘do both’ higher level skills and provide progression routes to improve their employability prospects. 
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\nThe ‘Blockchain’ (BC) facilitates digitized, decentralized, public ledger of all cryptocurrency transactions. It embraces a set of inter-related technologies. This paper expounds a novel BC-based architecture for transform centralised model of awarding and validation in to decentralized ledger of secured database. This database is shared, replicated, and synchronized for validation among the universities, partner institutions, professionals, statutory or regulatory bodies and industry bodies across the internet. The architecture offers secured collaborative validating system by qualification exchange with BC using trust methods within the decentralized topology.

Khalid Mahmood Malik, Hisham Kanaan, Vian Sabeeh, Ghaus M. Malik

To enable the vision of precision medicine, evidence-based medicine is the key element. Understanding the natural history of complex diseases like brain aneurysm and particularly investigating the evidences of its rupture risk factors relies on the existence of semantic-enabled data preparation technology to conduct clinical trials, survival analysis and outcome prediction. For personalized medicine in the field of neurological diseases, it is very important that multiple health organizations coordinate and cooperate to conduct evidence based observational studies. Without the means of automating the process of privacy and semantic-enabled data preparation to conduct observational studies at intra-organizational level would require months to manually prepare the data. Therefore, this paper proposes a semantic and privacy enabled, multi-party data preparation architecture and a four-tiered semantic similarity algorithm. Evaluation shows that proposed algorithm achieves a precision of 79%, high recall at 83% and F-measure of 81%.

Dominic Deuber, Matteo Maffei, Giulio Malavolta, Max Rabkin · 6 authors

Abstract A functional credential allows a user to anonymously prove possession of a set of attributes that fulfills a certain policy. The policies are arbitrary polynomially computable predicates that are evaluated over arbitrary attributes. The key feature of this primitive is the delegation of verification to third parties, called designated verifiers. The delegation protects the privacy of the policy : A designated verifier can verify that a user satisfies a certain policy without learning anything about the policy itself. We illustrate the usefulness of this property in different applications, including outsourced databases with access control. We present a new framework to construct functional credentials that does not require (non-interactive) zero-knowledge proofs. This is important in settings where the statements are complex and thus the resulting zero-knowledge proofs are not efficient. Our construction is based on any predicate encryption scheme and the security relies on standard assumptions. A complexity analysis and an experimental evaluation confirm the practicality of our approach.

Gaby G. Dagher, Jordan Mohler, Matea Milojkovic, Praneeth Babu Marella

No abstract is available for this record.

Barnaby Craggs, Awais Rashid

The Internet pervades many aspects of modern life offering up seemingly boundless opportunities to connect, inform and be informed. As the range and number of sources for information online explode, how people go about selecting and interpreting information has become a pertinent area for study, not least in the recent light of the prevalence of fake-news—as people are well known to act upon information they believe to be trustworthy. Where the decision to act incurs risk, an inability to accurately select and assess the credibility of information presents a challenge. <br/><br/>This extended abstract summarizes findings from a study of 57 Bitcoin users. Our analysis shows that this self-identifying technical and expert community was not significantly influenced by confirmation bias (a facet of fake-news). However, the same users also failed to demonstrate a true reliance upon the facts contained in news articles, often deferring trust to the source of the news which could still render them susceptible to fake-news, and, in turn, place their speculation of the crypto-currency at risk.

Tsung-Ting Kuo, Lucila Ohno‐Machado

Cross-institutional healthcare predictive modeling can accelerate research and facilitate quality improvement initiatives, and thus is important for national healthcare delivery priorities. For example, a model that predicts risk of re-admission for a particular set of patients will be more generalizable if developed with data from multiple institutions. While privacy-protecting methods to build predictive models exist, most are based on a centralized architecture, which presents security and robustness vulnerabilities such as single-point-of-failure (and single-point-of-breach) and accidental or malicious modification of records. In this article, we describe a new framework, ModelChain, to adapt Blockchain technology for privacy-preserving machine learning. Each participating site contributes to model parameter estimation without revealing any patient health information (i.e., only model data, no observation-level data, are exchanged across institutions). We integrate privacy-preserving online machine learning with a private Blockchain network, apply transaction metadata to disseminate partial models, and design a new proof-of-information algorithm to determine the order of the online learning process. We also discuss the benefits and potential issues of applying Blockchain technology to solve the privacy-preserving healthcare predictive modeling task and to increase interoperability between institutions, to support the Nationwide Interoperability Roadmap and national healthcare delivery priorities such as Patient-Centered Outcomes Research (PCOR).

Mumin Cebe, Enes Erdin, Kemal Akkaya, Hidayet Aksu · 5 authors

Today's vehicles are becoming cyber-physical systems that not only communicate with other vehicles but also gather various information from hundreds of sensors within them. These developments help create smart and connected (e.g., self-driving) vehicles that will introduce significant information to drivers, manufacturers, insurance companies, and maintenance service providers for various applications. One such application that is becoming crucial with the introduction of self-driving cars is forensic analysis of traffic accidents. The utilization of vehicle-related data can be instrumental in post-accident scenarios to discover the faulty party, particularly for self-driving vehicles. With the opportunity of being able to access various information in cars, we propose a permissioned blockchain framework among the various elements involved to manage the collected vehicle-related data. Specifically, we first integrate vehicular public key infrastructure (VPKI) to the proposed blockchain to provide membership establishment and privacy. Next, we design a fragmented ledger that will store detailed data related to vehicles such as maintenance information/ history, car diagnosis reports, and so on. The proposed forensic framework enables trustless, traceable, and privacy-aware post-accident analysis with minimal storage and processing overhead.

Haikel Magrahi, Nouha Omrane, Olivier Senot, Rakia Jaziri

Blockchains, such as Bitcoin and Ethereum and their respective P2P networks have seen significant adoption in many sectors in the past few years. All these technologies that use the Blockchain pattern show that it is possible to rebuild any transactional system with better performance without relying on any trusted parties to manage transactions between peers. This insight has lead many companies to invest millions to understand the technology and to find a way to migrate from centralized to decentralized solutions. These solutions need to store large amounts of data in a secure and confidential way. Many distributed storage systems now exist using Blockchain technology (Cloud, FileSystems, etc.). But none of the tools proposed are able to manage the document life cycle nor archive documents based on regulatory compliance. In this paper, we describe our protocol named NFB (Notarizing Files over the Blockchain). This protocol ensures the communication between two systems: a permissive Blockchain and a secured centralized archiving Document Management System. The method described is used to allow users to archive, control, analyze and validate their transactions in a system that offers confidentiality, security and distribution features.

Andreas Unterweger, Fabian Knirsch, Christoph Leixnering, Dominik Engel

Real-world smart contracts which preserve the privacy of both, their users and their data, have barely been proposed theoretically, let alone been implemented practically. In this paper, we are the first to implement a privacy-preserving protocol from the energy domain as a smart contract in Ethereum. We elaborate on and present our implementation as well as our practical findings, including more or less subtle traps and pitfalls. Despite major optimizations to our implementation, we find that while it is currently possible, it is not feasible to implement a privacy-preserving protocol of modest complexity in the Ethereum blockchain due to the high cost of operation and the lack of privacy by design.