Blockchain Papers

Xiaoxuan Chen, Yineng Chen, Xiayu Wang, Xinghui Zhu · 5 authors

Vehicular Ad Hoc Network (VANET) is an important part of the modern intelligent transportation system, which can provide vehicle communication at a certain distance. More importantly, VANET can provide route planning and autonomous driving for drivers by analyzing data. However, VANET’s data privacy and security are a huge challenge when serving drivers. In this paper, we propose a VANET data-sharing model (DSVN) that combines ciphertext-based attribute encryption (CP-ABE), blockchain, and InterPlanetary File System (IPFS). DSVN uses an outsourced and revocable ciphertext policy attribute-based encryption (ORCP-ABE) scheme, which is improved based on CP-ABE. ORCP-ABE uses key encryption key (KEK) trees to manage user attribute groups and revoke user-level attributes. It eliminates redundant attributes in the access policy by attribute-weighted access trees. Moreover, DSVN has no single point of failure. We demonstrate the indistinguishability under the chosen-plaintext attack (IND-CPA) security of DSVN by a game based on the computational Diffie–Hellman (CDH) assumption. Experimental results show that DSVN can store and share data with low overhead. Additionally, it can revoke attributes of users safely.

Mina Namazi, Ross Duncan, Xiaojie Zhu, Erman Ayday

Individuals are encouraged to prove their eligibility to access specific services regularly. However, providing various organizations with personal data spreads sensitive information and endangers people's privacy. Hence, privacy-preserving identification systems that enable individuals to prove they are permitted to use specific services are required to fill the gap. Cryptographic techniques are deployed to construct identity proofs across the internet; nonetheless, they do not offer complete control over personal data or prevent users from forging and submitting fake data. In this paper, we design a privacy-preserving identity protocol called "zkFaith." A new approach to obtain a verified zero-knowledge identity unique to each individual. The protocol verifies the integrity of the documents provided by the individuals and issues a zero-knowledge-based id without revealing any information to the authenticator or verifier. The zkFaith leverages an aggregated version of the Camenisch-Lysyanskaya (CL) signature scheme to sign the user's commitment to the verified personal data. Then the users with a zero-knowledge proof system can prove that they own the required attributes of the access criterion of the requested service providers. Vector commitment and their position binding property enables us to, later on, update the commitments based on the modification of the personal data; hence update the issued zkFaith id with no requirement of initiating the protocol from scratch. We show that the design and implementation of the zkFaith with the generated proofs in real-world scenarios are scalable and comparable with the state-of-the-art schemes.

Hai Zhang, Feng Zhao

In vehicular ad hoc networks (VANET), the cross-domain identity authentication of users is very important for the development of VANET due to the large cross-domain mobility of vehicle users. The Public Key Infrastructure (PKI) system is often used to solve the identity authentication and security trust problems faced by VANET. However, the PKI system has challenges such as too centralized Authority of Certification Authority (CA), frequent cross-domain access to certificate interactions and high authentication volume, leading to high certificate management costs, complex cross-domain authentication paths, easy privacy leakage, and overburdened networks. To address these problems, this paper proposes a lightweight blockchain-based PKI identity management and authentication architecture that uses smart contracts to reduce the heavy burden caused by CAs directly managing the life cycle of digital certificates. On this basis, a trust chain based on smart contracts is designed to replace the traditional CA trust chain to meet the general cross-domain requirements, to effectively avoid the communication pressure caused by a mass of certificate transmissions. For the cross-domain scenario with higher privacy and security requirements the identity attribute authentication service is provided directly while protecting privacy by using the Merkle tree to anchor identity attribute data on and off the blockchain chain. Finally, the proposed scheme was comprehensively analyzed in terms of cost, time consumption and security.

Yuan Liang, Qiang He, Siyu Tan, Bo Li · 7 authors

Multi-access Edge Computing (MEC) has emerged as a new distributed computing paradigm for its ability to offer low-latency services to users. Suffering from constrained computational resources because of their limited physical sizes, edge servers usually cannot handle all the incoming compute tasks on time when they operate independently. Thus, they need to cooperate by peer-offloading. Incentive and trust are the two major challenges towards to cooperative computing among edge servers operating in a distrusted environment. Another specific challenge in the MEC environment is to facilitate incentive and trust in a decentralized manner. This article proposes CoopEdge+, a novel blockchain-based decentralized platform, to drive and support cooperative multi-access edge computing to tackle these challenges in a systematic manner. On CoopEdge+, an edge server can publish a compute task for other edge servers to contend for. A winner is selected from candidate edge servers as the task executor based on their reputation to perform the compute task. After that, CoopEdge+ employs a random leader election scheme to elect a task recorder without revealing its leadership until its consensus epoch. The task recorder will coordinate a consensus among edge servers to record the task executor's performance on blockchain. We implement CoopEdge+ based on Hyperledger fabric and evaluate it experimentally against a baseline implementation and three state-of-the-art implementations in a simulated MEC environment. The results validate the usefulness of CoopEdge+ and demonstrate its performance.

Pratima Sharma, Suyel Namasudra, Naveen Chilamkurti, Byung‐Gyu Kim · 5 authors

Blockchain technology provides a secure and reliable platform for managing data in various application areas, such as supply chain management, multimedia, financial sector, food sector, Internet of Things (IoT) , healthcare, and many more. The recent emergence of blockchain with IoT provides significant growth in the healthcare industry to improve security, privacy, efficiency, and transparency with more business opportunities. Nevertheless, conventional healthcare schemes suffer from various security attacks like collusion, phishing, masquerade, etc. Therefore, a privacy-preserving Distributed Application (DA) is proposed in this paper using blockchain technology to create and maintain healthcare certificates. Here, the distributed application provides an interface between the blockchain network and system objects like healthcare centers, verifiers, and regular authorities to generate and issue medical documents. In addition, it also ensures security by specifying rules using various smart contracts. To evaluate the performance of the proposed scheme, various experimental tests are conducted using the Etherscan tool for measuring operation cost, latency, and processing time. Here, the efficiency of the proposed system is also compared to the existing systems in terms of latency, throughput, and response time. The experimental results and comparative analysis show that the proposed work is more efficient than the existing techniques.

Michael Sober, Max Kobelt, Giulia Scaffino, Dominik Kaaser · 5 authors

Distributed Key Generation (DKG) is an extensively researched topic as it is fundamental to threshold cryptosystems. Emerging technologies such as blockchains benefit massively from applying threshold cryptography in consensus protocols, randomness beacons, and threshold signatures. However, blockchains and smart contracts also enable further improvements of DKG protocols by providing a decentralized computation and communication platform. For that reason, we propose a DKG protocol that uses smart contracts to ensure the correct execution of the protocol, allow dynamic participation, and provide crypto-economic incentives to encourage honest behavior. The DKG protocol uses a dispute and key derivation mechanism based on Zero-Knowledge Succinct Non-interactive Arguments of Knowledge (zk-SNARKs) to reduce the costs of applying smart contracts by moving the computations off-chain, where the smart contract only verifies the correctness of the computation.

Fausto Neri da Silva Vanin, Lucas Micol Policarpo, Rodrigo da Rosa Righi, Sandra Marlene Heck · 7 authors

Personal health records (PHR) represent health data managed by a specific individual. Traditional solutions rely on centralized architectures to store and distribute PHR, which are more vulnerable to security breaches. To address such problems, distributed network technologies, including blockchain and distributed hash tables (DHT) are used for processing, storing, and sharing health records. Furthermore, fully homomorphic encryption (FHE) is a set of techniques that allows the calculation of encrypted data, which can help to protect personal privacy in data sharing. In this context, we propose an architectural model that applies a DHT technique called the interplanetary protocol file system and blockchain networks to store and distribute data and metadata separately; two new elements, called data steward and shared data vault, are introduced in this regard. These new modules are responsible for segregating responsibilities from health institutions and promoting end-to-end encryption; therefore, a person can manage data encryption and requests for data sharing in addition to restricting access to data for a predefined period. In addition to supporting calculations on encrypted data, our contribution can be summarized as follows: (i) mitigation of risk to personal privacy by reducing the use of unencrypted data, and (ii) improvement of semantic interoperability among health institutions by using distributed networks for standardized PHR. We evaluated performance and storage occupation using a database with 1.3 million COVID-19 registries, which showed that combining FHE with distributed networks could redefine e-health paradigms.

María José Gonçalves, Rui Humberto Pereira, Marta Alexandra Guerra Magalhães Coelho

User trust is a fundamental issue in e-commerce. To address this problem, recommendation systems have been widely used in different application domains including social media healthcare, e-commerce, and others. In this paper, we present a systematic review of the literature in the area of blockchain-based reputation models and we discuss the obtained results, answering the initial research questions. These findings lead us to conclude that the existing systems are based on a trusted third party (TTP) to collect and store reputation data, which does not provide transparency on users’ reputation scores. In the recent literature, on the one hand, blockchain-based reputation systems have been highlighted as possible solutions to effectively provide the necessary transparency, as well as effective identity management. On the other hand, new challenges are posed in terms of user privacy and performance, due to the specific characteristics of the blockchain. According to the literature, two major approaches have been proposed based on public and permissioned blockchains. Each approach applies adjusted models for calculating reputation scores. Despite the undoubted advantages added by a blockchain, the problem is only partially solved since there is no effective way to prevent blockchain oracles from feeding the chain with false, unfair, or biased data. In our future work, we intend to explore the two approaches discussed in the literature in order to propose a new blockchain-based model for deriving user reputation scores.

Jegadeesan Subramani, Azees Maria, Arun Sekar Rajasekaran, Fadi Al‐Turjman · 5 authors

Vehicular Ad-hoc Networks (VANETs) have a lot of potential for improving traffic management and driver safety. However, employing a wireless channel for vehicle communication has security and privacy concerns such as authentication, confidentiality, integrity, access control, and availability. Hence, it is indispensable to address the security and privacy aspects of the vehicles utilized in these contexts. In this study, a blockchain-based physically secure, and privacy-aware anonymous authentication technique leveraging the fog computing architecture. The proposed method can efficiently solve security and privacy problems using its attributes of support to movement, reduced latency, and location monitoring. In addition, the decentralized nature of blockchain technology is used to ensure the data security of vehicles. The vehicle is not required to store the secret keys to do anonymous authentication and provides physical security for the vehicle. The implied scheme provides essential security features with less storage, computational and communication costs than related competitive schemes.

Tahira Tariq, Faiza Javed, Syed Rizwan, Muhammad Zubair · 5 authors

The advancement of information technology may greatly benefit from the use of blockchain technology.Blockchain technology presents a promising future for protecting personal data. However, it does pose challenges concerning data security and risk that need to be overcome. This paper focused on examining the challenges posed by blockchain technology in terms of security and risk relating to the aspect of privacy. Furthermore, the regulation of the protection of personal data posed by blockchain technology has been taken into consideration. We focus on presenting security enhancement methods that regulators can take into account when drafting regulations on personal data protection guidelines. We also concentrate on the current methods for blockchain privacy protection as well as the future areas for study. The security and privacy-related challenges derived from its progressive maturity, complexity, lack of standardization, and diversity of protocols are superimposed on the demands of a vibrant, competitive environment. It is difficult to align it with the GDPR concerning privacy. There is an urgent need to develop multidisciplinary teams that must ensure its participation from the beginning of the legal/regulatory area, cybersecurity, and company information systems

Bhaskara S. Egala, Ashok Kumar Pradhan, Shubham Gupta, Kshira Sagar Sahoo · 6 authors

The recent COVID-19 pandemic has underlined the significance of digital health record management systems for pandemic mitigation. Existing smart healthcare systems (SHSs) fail to preserve system-level medical record openness and privacy while including mitigating measures such as testing, tracking, and treating (3T). In addition, current centralised compute architectures are susceptible to denial of service assaults because of DDoS or bottleneck difficulties. In addition, these current SHSs are susceptible to leakage of sensitive data, unauthorised data modification, and non-repudiation. In centralised models of the current system, a third party controls the data, and data owners may not have total control over their data. The Coviblock, a novel, decentralised, blockchain-based smart healthcare assistance system, is proposed in this study to support medical record privacy and security in the pandemic mitigation process without sacrificing system usability. The Coviblock ensures system-level openness and trustworthiness in the administration and use of medical records. Edge computing and the InterPlanetary File System (IPFS) are recommended as part of a decentralised distributed storage system (DDSS) to reduce the latency and the cost of data operations on the blockchain (IPFS). Using blockchain ledgers, the DDSS ensures system-level transparency and event traceability in the administration of medical records. A distributed, decentralised resource access control mechanism (DDRAC) is also proposed to guarantee the secrecy and privacy of DDSS data. To confirm the Coviblock’s real-time behaviour on an Ethereum test network, a prototype of the technology is constructed and examined. To demonstrate the benefits of the proposed system, we compare it to current cloud-based health cyber–physical systems (H-CPSs) with blockchain. According to the experimental research, the Coviblock maintains the same level of security and privacy as existing H-CPSs while performing considerably better. Lastly, the suggested system greatly reduces latency in operations, such as 32 milliseconds (ms) to produce a new record, 29 ms to update vaccination data, and 27 ms to validate a given certificate through the DDSS.

Randhir Kumar, Prabhat Kumar, Moayad Aloqaily, Ahamed Aljuhani

The recent technological advancements in wireless communication systems and the Internet of Things (IoT) have accelerated the development of zero touch networks (ZTNs). ZTNs provide self-monitoring, self-configuring, and automated service-level policies that cannot be fulfilled by the traditional network management and orchestration approaches. Despite the hype, the majority of data exchange between participating entities occurs over insecure public channels, which present a number of possible security risks and attacks. Toward this end, we first analyze the attack surface on IoT-enabled ZTNs and the inherent architectural flaws for such threats. After an overview of attack surface, this article presents a new deep-learning- and blockchain-assisted case study for secure data sharing in ZTNs. Specifically, first, we design a novel variational autoencoder (VAE) and attention-based gated recurrent units (AGRU)-based intrusion detection system (IDS) for ZTNs. Second, a novel authentication protocol that combines blockchain, smart contracts (SCs), elliptic curve cryptography (ECC), and a proof of authority (PoA) consensus mechanism is developed to improve secure data sharing in ZTNs. The extensive experimental results show the effectiveness of the proposed approach. Lastly, this work discusses critical issues, opportunities, and open research directions to solve these challenges.

Yepeng Ding, Hiroyuki Satō, Maro G. Machizawa

Data aggregation has been widely implemented as an infrastructure of data-driven systems. However, a centralized data aggregation model requires a set of strong trust assumptions to ensure security and privacy. In recent years, decentralized data aggregation has become realizable based on distributed ledger technology. Nevertheless, the lack of appropriate centralized mechanisms like identity management mechanisms carries risks such as impersonation and unauthorized access. In this paper, we propose a novel decentralized data aggregation framework by leveraging self-sovereign identity, an emerging identity model, to lift the trust assumptions in centralized models and eliminate identity-related risks. Our framework formulates the aggregation protocol regarding data persistence and acquisition aspects, considering security, efficiency, flexibility, and compatibility. Furthermore, we demonstrate the applicability of our framework via a use case study where we concretize and apply our framework in a decentralized neuroscience data aggregation scenario.

Stefano Marzo, Royston Pinto, Lucy McKenna, Rob Brennan

Federated learning (FL) is a distributed machine learning<br> approach that enables remote devices i.e. workers to collaborate to compute<br> the fitting of a neural network model without sharing their data.<br> While this method is favorable to ensure data privacy, an imbalanced<br> data distribution can introduce unfairness in the model training, causing<br> discriminatory bias towards certain under-represented groups. In this paper,<br> we show that imbalance federated data decreases indexes of equity<br> i.e. differences in treatment for underrepresented classes. To address the<br> problem, we propose a federated learning framework called Z-Fed that 1)<br> balances the training without exchange of privacy protected data using<br> a zero knowledge proof (ZKP) technique, and 2) allows for the collection<br> of information on data distributions based on one or more categorical<br> features to produce metadata about population proportions. The proposed<br> framework infers the precise data distribution without exchanging<br> knowledge of the data categories and uses it to coordinate a balanced<br> training set. Z-Fed aims to mitigate the effect of imbalanced data in<br> FL while respecting privacy and without using mediators or probabilistic<br> approaches. Compared to a non-balanced framework, Z-Fed improves<br> fairness and equality measured in equal opportunities (EPD) by 53.54%,<br> equal odds (EOD) by 56.41%, and statistical parity (SPD) by 46.1% on<br> imbalanced UTK datasets, reducing biased predictions among subgroups.<br> EPD, EOD, and SPD measure the disparity of treatment between privileged<br> e.g. over-represented and non-privileged groups. Given the results<br> obtained, Z-Fed can reduce discriminatory behaviors and enhance trustworthy<br> of federated learning.

Paulo Valente Klaine, Hao Xu, Lei Zhang, Muhammad Ali Imran · 5 authors

Recent data leak scandals, together with the under-utilization of collected data (estimated that around 90% of data never leaves a device’s local storage), limits the applicability and potential of novel data driven applications. Thus, novel ways to treat data, in which users are guaranteed control, usability, and privacy over their generated data are needed. In this paper we propose a novel privacy-preserving blockchain framework for a data sharing marketplace. The proposed framework allows users (such as sensors and devices) that generate data to store it in external servers, while the blockchain is utilized to record buy and sell transactions between parties, as well as perform access control by generating access sequences whenever trades are performed. A novel perspective over data ownership is presented, in which whoever generates the data has completed ownership and control over it and the blockchain transactions are only utilized to guarantee temporary access to it. The proposed blockchain framework also supports different types of data and provides, via the distributed and openness of the framework, quality, timeliness and similarity control over the data stored in the marketplace. In this context, different types of applications that can benefit from this framework are presented and open problems are discussed.

Haifa Mohammed Alanzi, Mohammad Alkhatib

An identity management system (IDMS) manages and organizes identities and credentials information exchanged between users, identity providers (IDPs), and service providers (SPs) to ensure confidentiality and enhance privacy of users’ personal data. Traditional or centralized IDMS rely on a third party to store a user’s personal information, authenticate the user, and organize the entire process. This clearly constitutes threats to the privacy of the user, in addition to other issues, such as single point of failure (SPOF), user tracking, and data availability issues. Blockchain technology has many useful features that can contribute to solving traditional IDMS issues, such as decentralization, immutability, and anonymity. Blockchain represents an attractive solution for many issues related to traditional IDMS, including privacy, third-party control, data leakage, and SPOF, supported by Distributed Ledger Technology (DLT) security features and powerful smart contracts technology. The current study presents a systematic literature review and analysis for recently proposed solutions that adopt the traditional centralized approach, as well as solutions based on blockchain technology. The study also aims to provide a deep understanding of proposed IDMS solutions and best practices, and highlight the research gaps and open issues related to IDMSs and users’ privacy. In particular, the current research focuses on analyzing the blockchain-based solutions and illustrating their strengths and weaknesses, as well as highlighting the promising blockchain technology framework that can be utilized to enhance privacy and solve security issues in a centralized IDMS. Such a study is an important step towards developing efficient solutions that address the pressing needs in the field.

Ha-Thanh Nguyen

The trade-off of secrecy is the difficulty of verification. This trade-off means that contracts must be kept private, yet their compliance needs to be verified, which we call the secrecy-verifiability paradox. However, the existing smart contracts are not designed to provide secrecy in this context without sacrificing verifiability. Without a trusted third party for notarization, the protocol for the verification of smart contracts has to be built on cryptographic primitives. We propose a blockchain-based solution that overcomes this challenge by storing the verifiable evidence as accessible data on a blockchain in an appropriate manner. This solution allows for cryptographic data verification but not revealing the data itself. In addition, with our proposal, it is possible to verify contracts whose form of existence has been destroyed as long as the contract is real and the people involved remember it.

Sayali Thorat, Sairaj Navale, Shubham Vadje, Mayur Rasal · 6 authors

As a digital system that integrates cryptography, data management, networking, and incentive mechanisms to allow the verification, execution, and recording of transactions between parties, block chains are now firmly established. Block chain technologies have significant potential as a new basis for all types of transactions, even though its initial purpose was to support new kinds of digital currency enabling simpler and more secure payments. By using this technology as a platform to carry out "smart contracts" for transactions, particularly for high-value products, agribusiness stands to become a primary benefactor. Prior to further discussion, it is crucial to make a distinction between private digital currencies and the underlying distributed ledger and block chain technology. Since digital currencies like Bitcoin are dispersed and international in nature, central banks are unlikely to be able to effectively regulate their underlying protocols. Instead than being able to monitor and control the money itself, monetary authorities are more concerned with comprehending the "on-ramps" and "off-ramps" that make up the linkages to the conventional payments system. Contrary to the block chain's digital currency component, the distributed ledger feature has the potential to be widely used in agricultural and trade financing, particularly if processes involve several partners and there is no reliable central authority.

Bintao He, Shangping Wang

Abstract The generation of the pseudonym in vehicular ad hoc networks (VANETs) usually requires the participation of a trusted center (TA), and it needs multiple interactions with the TA. To address these problems, we propose a novel traceable self-generated pseudonym based on the non-interactive zero-knowledge proof (NIZK) and consortium blockchain in VANETs. In our scheme, a self-generated pseudonyms method is introduced to eliminate excessive communication burden, and a consortium blockchain is composed of multiple roadside units (RSUs) to replace the TA. RSUs in the consortium blockchain verify the effectiveness of OBU’s self-generated pseudonyms through the consensus mechanism. Multiple trace authorities (TRAs) are designed to jointly tracking of the real identity of the OBU, which effectively prevents the abuse of supervision by the only supervisor.

Ying Miao Ying Miao, Qiong Huang Ying Miao, Meiyan Xiao Qiong Huang, Willy Susilo Meiyan Xiao

&lt;p&gt;Cloud storage provides convenience in managing data for users. Data integrity becomes important because data owner (DO) loses control of their data once it is uploaded to the cloud server (CS). Public auditing is used to check data integrity in cloud storage. Traditional public auditing schemes introduce a third-party auditor (TPA) to help users check their data. However, TPA is assumed to be trusted in these schemes, which may not be practical. A dishonest TPA may provide a good report to DO without executing the auditing task timely. If the data loss could not be detected timely, it may cause a great loss to DO. In this paper we aim to solve these problems using blockchain technique. In our scheme DO, TPA and CS interact with blockchain via smart contracts. We utilize a time-locked deposit smart contract to incentive TPA and CS for their fulfillment in the auditing task honestly. Otherwise, they would be amerced. We use storage smart contracts to ensure the auditing process transparency, and utilize zero-knowledge proof to protect DO&amp;rsquo;s privacy. The scheme is extended to support batch auditing to reduce the user&amp;rsquo;s cost. Experimental results show that our scheme is efficient and practical.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

James Scheibner, Marcello Ienca, Effy Vayena

Abstract Background Increasingly, hospitals and research institutes are developing technical solutions for sharing patient data in a privacy preserving manner. Two of these technical solutions are homomorphic encryption and distributed ledger technology. Homomorphic encryption allows computations to be performed on data without this data ever being decrypted. Therefore, homomorphic encryption represents a potential solution for conducting feasibility studies on cohorts of sensitive patient data stored in distributed locations. Distributed ledger technology provides a permanent record on all transfers and processing of patient data, allowing data custodians to audit access. A significant portion of the current literature has examined how these technologies might comply with data protection and research ethics frameworks. In the Swiss context, these instruments include the Federal Act on Data Protection and the Human Research Act. There are also institutional frameworks that govern the processing of health related and genetic data at different universities and hospitals. Given Switzerland’s geographical proximity to European Union (EU) member states, the General Data Protection Regulation (GDPR) may impose additional obligations. Methods To conduct this assessment, we carried out a series of qualitative interviews with key stakeholders at Swiss hospitals and research institutions. These included legal and clinical data management staff, as well as clinical and research ethics experts. These interviews were carried out with two series of vignettes that focused on data discovery using homomorphic encryption and data erasure from a distributed ledger platform. Results For our first set of vignettes, interviewees were prepared to allow data discovery requests if patients had provided general consent or ethics committee approval, depending on the types of data made available. Our interviewees highlighted the importance of protecting against the risk of reidentification given different types of data. For our second set, there was disagreement amongst interviewees on whether they would delete patient data locally, or delete data linked to a ledger with cryptographic hashes. Our interviewees were also willing to delete data locally or on the ledger, subject to local legislation. Conclusion Our findings can help guide the deployment of these technologies, as well as determine ethics and legal requirements for such technologies.

Muhammad Nazmul Islam, Mubashir Husain Rehmani, Jinjun Chen

The integration of permissioned blockchain such as Hyperledger fabric (HF) and Industrial internet of Things (IIoT) has opened new opportunities for interdependent supply chain partners to improve their performance through data sharing and coordination. The multichannel mechanism, private data collection and querying mechanism of HF enable private data sharing, transparency, traceability, and verification across the supply chain. However, the existing querying mechanism of HF needs further improvement for statistical data sharing because the query is evaluated on the original data recorded on the ledger. As a result, it gives rise to privacy issues such as leaking of business secrets, tracking of resources and assets, and disclosing of personal information. Therefore, we solve this problem by proposing a differentially private enhanced permissioned blockchain for private data sharing in the context of supply chain in IIoT which is known as (EDH-IIoT). First, we integrate differential privacy into the chaincode (smart contract) of HF which evaluates the query and adds a calibrated noise into it. Second, we propose an algorithm to efficiently utilize ϵ through reuse of the privacy budget for the repeated queries. Third, we also propose an algorithm to track the privacy budget (ϵ) and avoid the degrade of privacy preservation in case of multiple queries on the same portion of the ledger's data. Furthermore, the reuse and tracking of ϵ enables the data owner to ensure that ϵ does not exceed the threshold which is the maximum privacy budget (ϵt). Finally, we model two privacy attacks namely linking attack and composition attack to evaluate and compare privacy preservation, and the efficiency of reuse of ϵ with the default chaincode of HF and traditional differential privacy model, respectively. The results confirm that EDH-IIoT obtains an accuracy of 97% in the shared data for ϵ = 1, and a reduction of 35.96% in spending of ϵ.

Zhiming Song, Guiwen Wang, Yimin Yu, Taowei Chen

Due to the advantages in self-sovereignty identity management and scalability of blockchain, digital identity verification and management systems (DIVMS) of blockchain-based verifiable certificates (VC) are getting more and more attention. However, user privacy in the systems’ traditional architectures cannot be guaranteed. In this paper, the zero-knowledge succinct noninteractive arguments of knowledge (zkSNARKs) referred to as Groth16 are introduced in order to implement privacy protection of the user’s identity and behavior of DIVMS of blockchain-based VC. In the proposed architecture, the malleability attack of Groth16 is considered, and verifications of zero-knowledge proof (ZKP) and the digital signature of an identity provider (IDP) attached to VC and the status management of VC are implemented on the smart contracts of the blockchain to overcome single point failure. Furthermore, a prototype system is designed to verify the proposed architecture’s capability in privacy protection and to evaluate its performances in cost and throughput. Finally, the security of the proposed architecture is discussed, and its comparisons are conducted with those existing blockchain-based DIVMSs, especially those systems using Groth16 of zkSNARKs to improve the privacy of user. All results mentioned above have shown that the proposed system is efficient and safe, and it can improve the privacy of DIVMS of the blockchain based VC while avoiding single point failure.

Ronghua Xu, Yu Chen, Genshe Chen, Erik Blasch

The rapid development of three-dimensional (3D) acquisition technology based on 3D sensors provides a large volume of data, which are often represented in the form of point clouds. Point cloud representation can preserve the original geometric information along with associated attributes in a 3D space. Therefore, it has been widely adopted in many scene-understanding-related applications such as virtual reality (VR) and autonomous driving. However, the massive amount of point cloud data aggregated from distributed 3D sensors also poses challenges for secure data collection, management, storage, and sharing. Thanks to the characteristics of decentralization and security, Blockchain has great potential to improve point cloud services and enhance security and privacy preservation. Inspired by the rationales behind the software-defined network (SDN) technology, this paper envisions SAUSA, a Blockchain-based authentication network that is capable of recording, tracking, and auditing the access, usage, and storage of 3D point cloud datasets in their life-cycle in a decentralized manner. SAUSA adopts an SDN-inspired point cloud service architecture, which allows for efficient data processing and delivery to satisfy diverse quality-of-service (QoS) requirements. A Blockchain-based authentication framework is proposed to ensure security and privacy preservation in point cloud data acquisition, storage, and analytics. Leveraging smart contracts for digitizing access control policies and point cloud data on the Blockchain, data owners have full control of their 3D sensors and point clouds. In addition, anyone can verify the authenticity and integrity of point clouds in use without relying on a third party. Moreover, SAUSA integrates a decentralized storage platform to store encrypted point clouds while recording references of raw data on the distributed ledger. Such a hybrid on-chain and off-chain storage strategy not only improves robustness and availability, but also ensures privacy preservation for sensitive information in point cloud applications. A proof-of-concept prototype is implemented and tested on a physical network. The experimental evaluation validates the feasibility and effectiveness of the proposed SAUSA solution.