A Decentralized Information Marketplace Preserving Input and Output Privacy

Data-driven applications are engines of economic growth and essential for progress in many domains. The data involved is often of a personal nature. We propose a decentralized information marketplace where data held by data providers, such as individual users can be made available for computation to data consumers, such as government agencies, research institutes, or companies who want to derive actionable insights or train machine learning models with the data while (1) protecting input privacy, (2) protecting output privacy, and (3) compensating data providers for making their sensitive information available for secure computation. We enable this privacy-preserving data exchange through a novel and carefully designed combination of a blockchain that supports smart contracts and two privacy-enhancing technologies: (1) secure multi-party computations, and (2) robust differential privacy guarantees.</p

Adversarial contract design for private data commercialization

The proliferation of data collection and machine learning techniques has created an opportunity for commercialization of private data by data aggregators. In this paper, we study this data monetization problem using a contract-theoretic approach. Our proposed adversarial contract design framework accounts for the heterogeneity in honest buyers' demands for data, as well as the presence of adversarial buyers who may purchase data to compromise its privacy. We propose the notion of Price of Adversary (PoAdv) to quantify the effects of adversarial users on the data seller's revenue, and provide bounds on the PoAdv for various classes of adversary utility. We also provide a fast approximate technique to compute contracts in the presence of adversaries

Decentralized brokered enabled ecosystem for data marketplace in smart cities towards a data sharing economy

Presently data are indispensably important as cities consider data as a commodity which can be traded to earn revenues. In urban environment, data generated from internet of things devices, smart meters, smart sensors, etc. can provide a new source of income for citizens and enterprises who are data owners. These data can be traded as digital assets. To support such trading digital data marketplaces have emerged. Data marketplaces promote a data sharing economy which is crucial for provision of available data useful for cities which aims to develop data driven services. But currently existing data marketplaces are mostly inadequate due to several issues such as security, efficiency, and adherence to privacy regulations. Likewise, there is no consolidated understanding of how to achieve trust and fairness among data owners and data sellers when trading data. Therefore, this study presents the design of an ecosystem which comprises of a distributed ledger technology data marketplace enabled by message queueing telemetry transport (MQTT) to facilitate trust and fairness among data owners and data sellers. The designed ecosystem for data marketplaces is powered by IOTA technology and MQTT broker to support the trading of sdata sources by automating trade agreements, negotiations and payment settlement between data producers/sellers and data consumers/buyers. Overall, findings from this article discuss the issues associated in developing a decentralized data marketplace for smart cities suggesting recommendations to enhance the deployment of decentralized and distributed data marketplaces.publishedVersio

Autonomy, Efficiency, Privacy and Traceability in Blockchain-enabled IoT Data Marketplace

Personal data generated from IoT devices is a new economic asset that individuals can trade to generate revenue on the emerging data marketplaces. Blockchain technology can disrupt the data marketplace and make trading more democratic, trustworthy, transparent and secure. Nevertheless, the adoption of blockchain to create an IoT data marketplace requires consideration of autonomy and efficiency, privacy, and traceability. Conventional centralized approaches are built around a trusted third party that conducts and controls all management operations such as managing contracts, pricing, billing, reputation mechanisms etc, raising concern that providers lose control over their data. To tackle this issue, an efficient, autonomous and fully-functional marketplace system is needed, with no trusted third party involved in operational tasks. Moreover, an inefficient allocation of buyers’ demands on battery-operated IoT devices poses a challenge for providers to serve multiple buyers’ demands simultaneously in real-time without disrupting their SLAs (service level agreements). Furthermore, a poor privacy decision to make personal data accessible to unknown or arbitrary buyers may have adverse consequences and privacy violations for providers. Lastly, a buyer could buy data from one marketplace and without the knowledge of the provider, resell bought data to users registered in other marketplaces. This may either lead to monetary loss or privacy violation for the provider. To address such issues, a data ownership traceability mechanism is essential that can track the change in ownership of data due to its trading within and across marketplace systems. However, data ownership traceability is hard because of ownership ambiguity, undisclosed reselling, and dispersal of ownership across multiple marketplaces. This thesis makes the following novel contributions. First, we propose an autonomous and efficient IoT data marketplace, MartChain, offering key mechanisms for a marketplace leveraging smart contracts to record agreement details, participant ratings, and data prices in blockchain without involving any mediator. Second, MartChain is underpinned by an Energy-aware Demand Selection and Allocation (EDSA) mechanism for optimally selecting and allocating buyers' demands on provider’s IoT devices while satisfying the battery, quality and allocation constraints. EDSA maximizes the revenue of the provider while meeting the buyers’ requirements and ensuring the completion of the selected demands without any interruptions. The proof-of-concept implementation on the Ethereum blockchain shows that our approach is viable and benefits the provider and buyer by creating an autonomous and efficient real-time data trading model. Next, we propose KYBChain, a Know-Your-Buyer in the privacy-aware decentralized IoT data marketplace that performs a multi-faceted assessment of various characteristics of buyers and evaluates their privacy rating. Privacy rating empowers providers to make privacy-aware informed decisions about data sharing. Quantitative analysis to evaluate the utility of privacy rating demonstrates that the use of privacy rating by the providers results in a decrease of data leakage risk and generated revenue, correlating with the classical risk-utility trade-off. Evaluation results of KYBChain on Ethereum reveal that the overheads in terms of gas consumption, throughput and latency introduced by our privacy rating mechanism compared to a marketplace that does not incorporate a privacy rating system are insignificant relative to its privacy gains. Finally, we propose TrailChain which generates a trusted trade trail for tracking the data ownership spanning multiple decentralized marketplaces. Our solution includes mechanisms for detecting any unauthorized data reselling to prevent privacy violations and a fair resell payment sharing scheme to distribute payment among data owners for authorized reselling. We performed qualitative and quantitative evaluations to demonstrate the effectiveness of TrailChain in tracking data ownership using four private Ethereum networks. Qualitative security analysis demonstrates that TrailChain is resilient against several malicious activities and security attacks. Simulations show that our method detects undisclosed reselling within the same marketplace and across different marketplaces. Besides, it also identifies whether the provider has authorized the reselling and fairly distributes the revenue among the data owners at marginal overhead