Many Internet users employ a multitude of online services. Many services require the same data to be entered and users enter it repeatedly. Instead of entering information for every new service a user wants to use, we propose a system that allows users to simply share a set of information with any service they want to use. The information is entered once and stored in a distributed storage system. Users can easily share the data with any service provider, in order to use a service. Our proposed system makes use of the distributed ledger, provided by blockchains, to manage access rights. By taking the data away from the service providers, the personal data is also protected against unwanted data leaks.
M. Magdalena Payeras–Capellà, Macià Mut–Puigserver, Miquel À. Cabot-Nadal
European Regulation (EU) 910/2014 lays down the rules for electronic identification and trust services for electronic transactions. Qualified Electronic Registered Delivery is one of the trust services included in the regulation, and it requires nonrepudiation of origin and reception together with the integrity of the data. This kind of services usually relies heavily on the use of trusted third parties. These entities are an obstacle to extend the use of protocols. In this paper, we use the blockchain-based technologies to provide, for the first time, two multiparty registered eDelivery schemes that reduce the involvement of trusted third parties compared with traditional approaches while satisfying the requirements of the norms created by the European Union for registered eDeliveries. Since confidentiality is not considered a compulsory property in the directive, we propose two protocols. The first one is well suited for those deliveries that do not require the confidentiality of the message or delivered data or even for those in which it is required that the message can be public and accessible to everybody. The second solution for multiparty registered eDelivery allows the message to be hidden to others than the receiver. We present the smart contracts for both proposals and also a complete analysis of their properties and performance.
The abundance of data available on public blockchain environments might expose users to privacy breaching. Ethereum as the largest host of blockchain-based project currently has no robust protection against such threats. In this paper, a proof-of-concept decentralized application is implemented demonstrating privacy preserving transaction flow in Ethereum environment using zero-knowledge cryptography (zk-SNARK ). The design of the application utilized an experimental package, EY Nightfall and focuses on a blind auction scenario where personal informations needs to be protected. The proof-of-concept is then analysed to weigh the financial and temporal costs of the implementations against the security advantages and was found to be feasible for non fast-paced settings and significantly large transactions.
We propose that blockchain technology complemented by secure computation methods can foster implementation of a learning healthcare system (LHCS) by minimizing upfront patient-facing compromises with unsurpassed data security and privacy, and by optimizing the system’s fulfillment of its obligations to respect patients through transparency, engagement, and accountability. We demonstrate how a blockchain-enabled LHCS could foster patient willingness to contribute to learning by providing desired security and control over health data. In addition, secure computation methods could enable meta-analysis without exposing individual-level data, thus allowing the system to protect patients’ privacy while simultaneously learning from their data. The transparency and immutability of blockchain ledgers would also support the public’s trust in the system by allowing patients to audit and oversee which of their data are used, how they are used, and by whom. Furthermore, blockchain communities are community-governed peer-to-peer networks in which sharing builds mutually beneficial value, offering a model for engaging patients as LHCS stakeholders. Smart contracts could be used to ensure accountability of the system by embedding feedback mechanisms by which patients directly and automatically realize benefits of sharing their data.
Group signature schemes enable a set of members to anonymously sign data on behalf of the entire group. In order to prevent misuse, a designated group manager<br>has the ability to trace a given signature back to a member. Other extensions can also be realized in speci ffically designed schemes, such as veri fier local revocation (VLR) wherein only the verifi er needs information about the validity status of signing key pairs. This paper contributes two results towards group signature schemes. First, we present a new design for a group signature scheme that is secure under the standard<br>model, with common relaxations for anonymity. The scheme also enables VLR and allows for fully-dynamic groups; i.e. groups that allow members to both leave and join after creation. Secondly, we implement a preliminary version of the scheme to begin investigating the effi ciencies gained through utilizing one-time signing keys, instead of the traditional non-interactive, zero-knowledge proof systems.
Blockchains offer opportunities for developing advanced digital services. While current research on this topic is still growing, various security concerns have been raised and the security of blockchains has been becoming the most important issue which must be well addressed. Blockchain transactions are based on digital signatures, where the public key is associated with the ownership of the digital coin. User management of public or permissionless blockchain is ad hoc, i.e., any user can join and leave the blockchain network and participate in the Proof of Work (PoW). However, in a private blockchain and a permissioned blockchain, there are usually some constraints for users. In this paper, we investigate a scenario which provides a blockchain network with a set of policies where every user's signing key is associated with a policy set. It is particularly interesting while users are working in different sectors. We call our scheme as “policy-driven”, since policies in our scheme restrict users' rights. Our system is featured with a novel and lightweight policy-driven signature (PDS) scheme whose security has been proven formally. To justify our scenario, we provide experimental results and an example for the railway management services.
Shihan Bao, Yue Cao, Ao Lei, Philip Asuquo · 7 authors
Research into the established area of the intelligent transportation system is evolving into the Internet of Vehicles, a fast-moving research area, fuelled in part by rapid changes based on cyber-physical systems. It needs to be recognized that existing vehicular communication systems are susceptible to privacy vulnerabilities which require addressing. A practical challenge is that many vehicular communication applications and services make use of basic safety messages that contain the identity of the vehicle, location, and other personal data. A popular way of dealing with this privacy issue is to utilize a pseudonym change scheme to protect the vehicle's identity and location. However, many such schemes suffer that the cost grows and the certificate management difficulty raises with the number of pseudonyms generated and stored, casting doubt of the economic feasibility of that approach. We propose a decentralized blockchain-based solution for pseudonym management that overcomes these limitations. This scheme consists of pseudonym distribution and a shuffle operation, allowing the reuse of existing pseudonyms to different vehicles. The results reported here, including those from our simulations, demonstrate that the proposed scheme can reuse existing pseudonyms and achieve a better degree of anonymity at a lower cost than existing schemes.
Jan 1, 2019·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Practitioners as well as academics expect that blockchain technology is a game changer for a variety of use cases. This is because of its feature of transaction immutability enabled by keeping a history of all transactions. Nevertheless, this strength can become its biggest weakness. There already exists a lively discussion on scenarios where it is necessary to delete submitted data from the chain after it is no longer needed. This becomes even more crucial with the introduction of the European General Data Protection Regulation (GDPR). In this paper we make use of a design science research (DSR) approach to design an IT artifact in form of a prototype that maintains most of the key features of blockchain technology but deletes old data. We evaluate the prototype with help of experts to investigate what to expect from blockchains that delete data and derive principles on how to design them.
Collection and management of clinical data for administration and analysis is a time-consuming and complex task, especially when multiple data providers been involved. Even if people are willing to take on the burden for it, there is still no mature solution to protect data privacy for distributed data providers. Distributed ledger is an emerging technology that supports decentralized data sharing and management. Based on this, we present a platform which enables distributed and truthful data collection and serves privacy-preserving needs in clinical data management. Our system, built on Hyperledger Fabric, used smart contract to execute data aggregation and provide basic analysis methods. The system used ledger and world status to record data access history and other metadata. This decentralized platform enables data providers to proactively share and protect their data, Thus can simplify clinical data collection procedure and promote efficient collaboration between providers.
In a non-interactive zero-knowledge (NIZK) proof, a prover can non-interactively convince a verifier of a statement without revealing any additional information. Thus far, numerous constructions of NIZKs have been provided in the common reference string (CRS) model (CRS-NIZK) from various assumptions, however, it still remains a long standing open problem to construct them from tools such as pairing-free groups or lattices. Recently, Kim and Wu (CRYPTO’18) made great progress regarding this problem and constructed the first lattice-based NIZK in a relaxed model called NIZKs in the preprocessing model (PP-NIZKs). In this model, there is a trusted statement-independent preprocessing phase where secret information are generated for the prover and verifier. Depending on whether those secret information can be made public, PP-NIZK captures CRS-NIZK, designated-verifier NIZK (DV-NIZK), and designated-prover NIZK (DP-NIZK) as special cases. It was left as an open problem by Kim and Wu whether we can construct such NIZKs from weak paring-free group assumptions such as DDH. As a further matter, all constructions of NIZKs from Diffie-Hellman (DH) type assumptions (regardless of whether it is over a paring-free or paring group) require the proof size to have a multiplicative-overhead \(|C| \cdot \mathsf {poly}(\kappa )\), where |C| is the size of the circuit that computes the \(\mathbf {NP}\) relation.
In a general secure multi-party computation (MPC) protocol, two or more participants who do not trust each other, use their respective secret inputs to calculate a joint function in a distributed environment without a centralized organization. They can get correct outputs on the premise of ensuring privacy and independence of input. In this paper, to solve the problem of fairness and robustness in MPC, a blockchain-based multi-party computation scheme (BFR-MPC) was proposed. The blockchain maintains an open reputation system for parties as a public ledger where a more reputable party has a greater chance to be selected. The block height is used as a trusted timestamp. In each round, parties must send the correct information before the deadline. In our scheme, all parties are considered to be foresighted, and an incentive mechanism encourages parties to cooperate rather than deviate from the protocol. Because of non-cooperative parties will be immediately expelled from the protocol and will be penalized financially, the proposed scheme is robust. The penalty will be used to reward honest parties. We also proved the fairness of our scheme through Game Theory. The comparison results of the proposed scheme with other schemes show that it is a more practical scheme for MPC with high fairness and robustness.
In the Internet of Things (IoT), a cyber physical system (CPS) has achieved great success in a wide range of distributed integration environments. In the cyber physical system (CPS), interconnected sensing devices collect data in the surrounding environment and send data to all interested nodes through the network, thereby sharing all nodes data. This process can be implemented by using a publish/subscribe (pub/sub for short) system. Providing the basic security mechanisms such as authorization and confidentiality is a challenge due to the loose coupling of subscribers and publishers in such a pub/sub system. At the meanwhile, the existing IoT ecosystem mostly relies on a centralized server and thus faces the problem of single point failure. Thus, it is interesting to realize a brokerless or decentralized pub/sub model. Inspired by this motivation, this paper mainly proposes a privacy-preserving publish/subscribe model by using the blockchain technique, which evades the centralized trustroot setting and the problem of single point failure. Another key point of our proposal is that the primitive of public key encryption with equality test (PKEwET) is employed to enable all the required authorization, communication and topics matching can be finished in a confidential manner. Finally, a lightweight prototype of our proposal is implemented by using web3j, and the security and efficiency analysis are also presented.