As cyber-physical systems (CPS) flourish, the data security issues it encounters have increasingly become a research focus in the field. And it has received widespread attention from academia and industry. Blockchain technology has the characteristics of decentralization, openness, transparency, reliability and non-tampering. It has natural advantages in solving the security of the CPS. Thus, this paper first analyzes the security risks associated with data storage in cyber-physical systems and proposes the use of blockchain technology to ensure the secure storage of data in CPS. In traditional blockchains, the data layer uses Merkle hash trees to store data; however, the Merkle hash tree cannot batch add/delete and provide non-membership proof. In order to solve this problem, this paper improves the accumulator and uses the combination of accumulator and Merkle hash tree to provide batch addition/removal and non-membership proof. This paper constructs a Merkle hash tree accumulator, and proves that the scheme is feasible through correctness and security.
We establish the optimal security threshold for the Bitcoin protocol in terms of adversarial hashing power, honest hashing power, and network delays. Specifically, we prove that the protocol is secure if [ra < 1/Δ0 + 1/rh,,] where rh is the expected number of honest proof-of-work successes in unit time, ra is the expected number of adversarial successes, and no message is delayed by more than Δ0 time units. In this regime, the protocol guarantees consistency and liveness with exponentially decaying failure probabilities. Outside this region, the simple private chain attack prevents consensus. Our analysis immediately applies to any Nakamoto-style proof-of-work protocol; in the full version of this paper we also present the adaptations needed to apply it in the proof-of-stake setting, establishing a similar threshold there.
Behzad Abdolmaleki, Sebastian Ramacher, Daniel Slamanig
Zero-knowledge proofs and in particular succinct non-interactive zero-knowledge proofs (so called zk-SNARKs) are getting increasingly used in real-world applications, with cryptocurrencies being the prime example. Simulation extractability (SE) is a strong security notion for zk-SNARKs which informally ensures non-malleability of proofs. The high importance of this property is acknowledged by leading companies in this field such as Zcash and underpinned by various attacks against the malleability of cryptographic primitives in the past. Another problematic issue for the practical use of zk-SNARKs is the requirement of a fully trusted setup, as especially for large-scale decentralized applications finding a trusted party that runs the setup is practically impossible. Quite recently, the study of approaches to relax or even remove the trust in the setup procedure, and in particular subversion as well as updatable zk-SNARKs (with latter being the most promising approach), has been initiated and received considerable attention since then. Unfortunately, so far SE-SNARKs with the aforementioned properties are only constructed in an ad-hoc manner and no generic techniques are available.
Karl Wüst, Siniša Matetić, Silvan Egli, Kari Kostiainen · 5 authors
Smart contracts are programmable, decentralized and transparent financial applications. Because smart contract platforms typically support Turing-complete programming languages, such systems are often said to enable arbitrary applications. However, the current permissionless smart contract systems impose heavy restrictions on the types of computations that can be implemented. For example, the globally-replicated and sequential execution model of Ethereum requires low gas limits that make many computations infeasible.
Purpose The purpose of this paper is to present a concept of the protocol for public registries based on blockchain. New database protocol aims to use the benefits of blockchain technologies and ensure their interoperability. Design/methodology/approach This paper is framed with design science research (DSR). The primary method is exaptation, i.e. adoption of solutions from other fields. The research is looking into existing technologies which are applied here as elements of the protocol: Name-Value Storage (NVS), Berkley DB, RAID protocol, among others. The choice of NVS as a reference technology for creating a database over blockchain is based on the analysis and comparison with two other similar technologies Bigchain and Amazon QLDB. Findings The proposed mechanism allows creating a standard database over a bundle of distributed ledgers. It ensures a blockchain agnostic approach and uses the benefits of various blockchain technologies in one ecosystem. In this scheme, blockchains play the role of journal storages (immutable log), whereas the overlaid database is the indexed storage. The distinctive feature of such a system is that in blockchain, users can perform peer-to-peer transactions directly in the ledger using blockchain native mechanism of user access management with public-key cryptography (blockchain does not require to administrate its database). Originality/value This paper presents a new method of creating a public peer-to-peer database across a bundle of distributed ledgers.
Anders Dalskov, Daniele Lain, Enis Ulqinaku, Kari Kostiainen · 5 authors
Encrypted cloud storage services are steadily increasing in popularity, with many commercial solutions currently available. In such solutions, the cloud storage is trusted for data availability, but not for confidentiality. Additionally, the user's device is considered secure, and the user is expected to behave correctly. We argue that such assumptions are not met in reality: e.g., users routinely forget passwords and fail to make backups, and users' devices get stolen or become infected with malware. Therefore, we consider a more extensive threat model, where users' devices are susceptible to attacks and common human errors are possible. Given this model, we analyze 10 popular commercial services and show that none of them provides good confidentiality and data availability. Motivated by the lack of adequate solutions in the market, we design a novel scheme called Two-Factor Encryption (2FE) that draws inspiration from two-factor authentication and turns file encryption and decryption into an interactive process where two user devices, like a laptop and a smartphone, must interact. 2FE provides strong confidentiality and availability guarantees, as it withstands compromised cloud storage, one stolen or compromised user device at a time, and various human errors. 2FE achieves this by leveraging secret sharing with additional techniques such as oblivious pseudorandom functions and zero-knowledge proofs. We evaluate 2FE experimentally and show that its performance overhead is small. Finally, we explain how our approach can be adapted to other related use cases such as cryptocurrency wallets.
Education is a business process that has been a pillar of government for centuries in building the nation. The method of organizing knowledge globally does not change according to the times. Various problems currently faced by education service providers, especially at the tertiary level, in this case, call it the problem of authentication and certificate verification, which are the micro and macro outputs of a learning process. People are getting lighthouses about blockchain, the solution to educational polemic problems. The combination of science between education and blockchain technology will create a new revolution in the education industry that is felt to be stagnant and incompatible with current developments. There are various kinds of insights from this solution. Still, it is not enough to explain the ontology of education using blockchain, which, as a whole, discusses the existence of blockchain for education based on scientific studies. Ontology for knowledge will be useful as a literature platform for young researchers, especially in universities, to start basic and applied research that leads to blockchain in education. Besides, blockchain technology has weaknesses and inefficiencies, namely in terms of cost, storage space, and speed. Solutions will be proposed through this research regarding on-chain and off-chain protocols in Time Based Protocol (TBP), which is part of Blockchain technology. As a result, this research can also become the foundation for new platforms and frameworks as a solution for the government in launching blockchain-based education, which is a pioneer in creating a blockchain-based government.
The process of implementing education globally basically cannot keep up with current developments. The education sector is currently facing various problems; in this case, the issue of verification and the existence of a third party in handling certificates are the micro and macro results of a learning process. A lighthouse about Blockchain technology is often cited as one of the revolutionary solutions to educational polemics so far. The combination of educational technology with blockchain technology will create revolutionary technology in the education industry. There are various kinds of insight from this problem, but this cannot explain the blockchain manifesto in detail from education for learning based on scientific studies. This blockchain manifesto in the future will be useful as a literature platform for researchers who will begin basic and applied research leading to blockchain for education. Besides, in terms of cost, storage space, and blockchain technology speed, a solution will be proposed in the form of a framework. As a result, this research can also become a new blockchain platform and manifesto as the blockchain technology-based government's embryo.
Anik Islam, Md Masuduzzaman, Arifa Akter, Soo Young Shin
Internet of Things (IoT) established the foundation of the smart world via its diverse functionalities (e.g., remote data acquisition, automated task execution). This trend continues to military applications too by introducing internet of military things (IoMT). Due to being at infancy level, new technologies require to move forward and assist IoMT to gain maturity. Mixed reality (MR) can be a potential technology which fuses the virtual and actual world. MR can improve the quality of service (QoS) in terms of inventory management, remote mission handling, battlefield assistance, etc. However, data among these applications is surrounded by cyber threats (e.g., illegal data modification, unauthorised data access). Blockchain is another promising technology which brings security in the distributed world. A content sharing scheme for MR application is proposed on the top of blockchain to bring security in the multi-user environment in IoMT. A smart contract is employed to manage security in accessing data by different users. Moreover, an experimental environment is set to observe the performance of the proposed scheme. The analysis manifests that proposed scheme maintains security without affecting the regular performance.
Blockchain has been a new technology that involves an emergent evolution of many areas, particularly in finance, healthcare and supply chain. Due to its remarkable features including immutability, decentralization, peer-to-peer networking and capability to corporate with data protection and privacy, it is attractive to system integration. In traditional system integration architecture, a central mediator with a silo to store transactions stands in the center of integration to provide trust and transparency for participated systems. Hence existing central mediator could become a possible target of Distributed Denial of Service (DDoS) cyberattack and single point of failure. This paper presents a blockchain-base system architecture and its implementation for system integration which doesn't need a central mediator. The blockchain-based system has been implemented using Ethereum Blockchain in compliance with the General Data Protection Regulation (GDPR) standard to support the integration of DNA profiles information systems.
Industry 4.0 heavily uses connected machine paradigm to automate, track and maintain processes. However, a major challenge in Industrial Internet-of-Things (IIoT) remains managing the burgeoning number of sensors. The centralized framework for managing these devices is raising concerns. In this work, we propose a novel proof-of-concept framework for managing identity and access management policies for IIoT. The new framework is a smart contract enabled and blockchain based decentralized life-cycle and access management system. It is backed by decentralized storage technology InterPlanatery FileSystem (IPFS). Our framework is decentralized and scalable unlike the state-of-the-art IIoT management frameworks designed for clouds which are centralized.
João Paulo de Brito Gonçalves, Roberta Lima Gomes, Rodolfo da Silva Villaça, Esteban Municio · 5 authors
Service Level Agreements (SLAs) are used to establish a contract, an agreement between two parties, which can be between two operators, or between a customer and an operator. The SLAs methods are a key aspect between consumers and providers, which can continuously monitor the Quality of Service (QoS) attributes and enforce its reliability, but the SLA also needs an entity to manage it. Smarts contracts are programs that are executed in a blockchain and ensure integrity and reliability to data stored in the distributed structure. This work proposes a solution using smarts contracts and blockchains in order to simplify the process of SLA validation.
Mohammed Misbhauddin, Abdulaziz AlAbdulatheam, Mohammed Aloufi, Hussien Al-Hajji · 5 authors
Electronic Health Record is a digital version of a patient's medical history maintained by a healthcare provider over the course of their visits. Unfortunately, medical records of one patient is fragmented across many hospitals, private clinics, labs, pharmacies and personal health records from wearables. Healthcare providers hesitate to share “proprietary” data. This is where the blockchain technology comes in use. Moreover, blockchain opens the opportunity to record patients' records as blocks, encrypt and make it impossible (immutable) to proceed with any changes for the information stored. The main goal would be to take advantage of the blockchain technology provide immutability, data integrity where each record is privately encrypted and publicly viewed. Nevertheless, the overall cost to store information in a practical blockchain itself is very expensive. This is where a decentralized P2P network that can store the data off-the-chain would assist in storing the actual content of each medical record and only the identifier is sent and stored on the blockchain. Any individual would be able to publicly view the medical record, however, only patients possess the private key and hence share it with desired individuals e.g. physicians or any medical practitioner. In this paper, we propose an architecture that can be used to develop scalable blockchain applications using an off-chain solution that will allow physicians, lab technicians and patients to manage the medical records in a secure manner.
The Common Data Model (CDM) is being used to deal with problems caused by the various electronic medical record structures in the distributed hospital information system. The concept of CDM is emerging as a collaborative method of exchanging data from each hospital in the same format and conducting various clinical studies based on shared data. The baseline of a CDM system is centralized with an infrastructure typically controlled by a single entity with full authority. The characteristics of this centralized system can pose serious security issues. Therefore, the proposed SC-CDM system is designed as a platform for distributed ledger and provides data with a high level of confidentiality, security, and scalability. This framework provides a reference model that supports multiple channels, using secure CDM as an encryption method. The data confidentiality of CDM is guaranteed by asymmetric and symmetric protocols. Delivering CDM is protected by a symmetric key signed by the CDM creator and maintains lightweight distributed ledger transactions on Inter Planetary File System (IPFS), which acts as a file share. To deliver an encrypted CDM on the SC-CDM platform, the CDM is encrypted with a block cipher by a random symmetric key and Initialization Vector (IV). The symmetric key protocol is used for the fast encryption of large-capacity data. The SC-CDM is implemented the repository with IPFS for storing the encrypted CDM, in which symmetric key, two hash values, and IV are shared through blockchain. Data confidentiality of SC-CDM is guaranteed by only registered users accessing the data. In conclusion, the SC-CDM is the first approach to demultiplexing with the data confidentiality proof based on asymmetric key cryptography. We analyze and verify the security of SC-CDM by comparing qualitative factors and performance with existing CDM. Moreover, we adopt a byte-level processing method with encryption to ensure efficiency while handling a large CDM.
Managing identity across an ever-growing digital services landscape has become one of the most challenging tasks for security experts. Over the years, several Identity Management (IDM) systems were introduced and adopted to tackle with the growing demand of an identity. In this series, a recently emerging IDM system is Self-Sovereign Identity (SSI) which offers greater control and access to users regarding their identity. This distinctive feature of the SSI IDM system represents a major development towards the availability of sovereign identity to users. uPort is an emerging open-source identity management system providing sovereign identity to users, organisations, and other entities. As an emerging identity management system, it requires meticulous analysis of its architecture, working, operational services, efficiency, advantages and limitations. Therefore, this paper contributes towards achieving all of these objectives. Firstly, it presents the architecture and working of the uPort identity management system. Secondly, it develops a Decentralized Application (DApp) to demonstrate and evaluate its operational services and efficiency. Finally, based on the developed DApp and experimental analysis, it presents the advantages and limitations of the uPort identity management system.
Proofs of retrievability and proofs of replication are two cryptographic tools that enable a remote server to prove that the users' data has been correctly stored. Nevertheless, the literature either requires the users themselves to perform expensive verification jobs, or relies on a “fully trustworthy” third party auditor (TPA) to execute the public verification. In addition, none of existing solutions consider the underlying incentive issues behind a rational server who is motivated to collect users' data but tries to evade the replication checking in order to save storage resources. In this article, we propose the first decentralized system for proofs of data retrievability and replication-BOSSA, which is incentive-compatible for each party and realizes automated auditing atop off-the-shelf blockchain platforms. We deal with issues such as proof enforcements to catch malicious behaviors, new metrics to measure the contributions, and reward distributions to create a fair reciprocal environment. BOSSA also incorporates privacy-enhancing techniques to prevent decentralized peers (including blockchain nodes) from inferring private information about the outsourced data. Security analysis is presented in the context of integrity, privacy, and reliability. We implement a prototype based on BOSSA leveraging the smart contracts of Ethereum blockchain. Our extensive experimental evaluations demonstrate the practicality of our proposal.
Oct 8, 2020·Proceedings of the Twenty-First International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing
Proof of Capacity (PoC) is an eco-friendly alternative to Proof of Work for consensus in blockchains since it determines mining rights based on miners' storage rather than computation. In PoC, for every block, a miner executes hashing on part of his dedicated storage. The miner that comes up with the smallest hash value among all miners will win the block. PoC has yet to be applied to mobile applications, due to the storage limitation of mobile devices. Storage offloading can be a viable solution that allows miners to offload mining all files to a cloud storage. In each mining round, a miner can decide whether to mine on his local device or by a cloud virtual machine (VM). Self-mining requires no extra cost but it incurs download delay, which will reduce the chance of winning. Cloud-mining experiences no delay but it brings cost on VMs. This delay-cost tradeoff challenges each miner to determine a ratio between self-mining and cloud-mining to maximize his utility. We model interactions among miners as a non-cooperative game and formulate a Nash equilibrium problem to investigate the effects of offloading on miners' utilities. We analyze the existence and uniqueness of equilibrium and propose a distributed algorithm to achieve the equilibrium in a uniform-delay setting. Further, we extend our results to non-uniform delays since miners may choose different network settings, e.g. 5G, 4G, or 3G. Both numerical evaluation and testbed experiments on Burstcoin are conducted to show the feasibility of storage offloading and to validate the proposed models and theoretical results.
Aye Mi San, Nopporn Chotikakamthorn, Chanboon Sathitwiriyawong
Many blockchain-based learning credential systems have been proposed to reduce fraud and improve verification efficiency. In addition to a method for issuing and verifying credentials, a solution is needed to support the revision and revocation of an issued credential record. For the case of learning credentials, depending on how a revocation policy affects credential use that occurred before the revocation date, an additional mechanism may be needed for credential revision. Current digital learning credential methods offer only a revocation mechanism. So they do not fully meet such unique requirement in the education context. In this paper, a blockchain-based method for learning credential revision and revocation is proposed. It makes use of the revision and revocation addresses assigned to each batch of issuing credentials. To revise (revoke) one or more credentials, the proposed method stores the revision (revocation) list as a message in the OP_RETURN field of the revision (revocation) transaction, with the revision (revocation) address as one of its outputs. The concept of a local credential id has been introduced to allow a revision (revocation) list to be efficiently stored on a blockchain system. It is based entirely on a blockchain system and does not require any centralized authority. It is also applicable to most blockchain systems. A comparative study of the proposed method against existing credential revocation methods is also provided.
Qikun Zhang, Yongjiao Li, Ruifang Wang, Lu Liu · 6 authors
With the widespread application of Industrial Internet of Things (IIoT) technology in the industry, the security threats are also increasing. To ensure the safe sharing of resources in IIoT, this paper proposes a data security sharing model based on privacy protection (DSS-PP) for blockchain-enabled IIoT. Compared with previous works, DSS-PP has obvious advantages in several important aspects: (1) In the process of identity authentication, it protects users' personal information by using authentication technology with hidden attributes; (2) the encrypted shared resources are stored in off-chain database of the blockchain, while only the ciphertext index information is stored in the block. It reduces the storage load of the blockchain; (3) it uses blockchain logging technology to trace and account for illegal access. Under the hardness assumption of Inverse Computational Diffe–Hellman (ICDH) problem, this model is proven to be correct and safe. Through the analysis of performance, DSS-PP has better performance than the referred works.
In the shipping industry, a significant part of the documents exchanges still have the traditional paper form, mainly due to security concerns, despite the size and modernization efforts of this market. We explore the adoption of the blockchain and Distributed Ledger Technologies to address document exchange in a fast and secure way.
ABSTRACT Blockchain and distributed ledger technologies are changing the way financial and business records are created and stored. New approaches to collaboration within and across industries enabled by this technology will increasingly result in new opportunities for data analysis and enable fundamental changes in accounting and auditing. The importance of this technology is increasing and “CPAs will need to learn, adjust, and adapt to emerging uses of blockchain” (AICPA 2020). This paper presents a pencil-and-paper activity that can help students unfamiliar with blockchain-related technologies understand these systems, the inter-organizational databases that result from their use, and their potential impacts for the accounting profession. We include optional reference materials that can be used as background reading for faculty members unfamiliar with blockchain or that can be integrated into a course.
Recently, the use of blockchain technology in the field of healthcare has increased. Although blockchain technology brought several innovations to healthcare, still there are problems waiting to be resolved. In order to provide alternative solutions to these problems, the use of fog computing together with blockchain technology has been proposed. In this study, the applications of blockchain based fog computing technology in healthcare are investigated. The aim of this study is to provide the readers an idea about the interactive use of blockchain and fog computing in the field of healthcare. For this purpose, firstly, fog computing and blockchain technologies are introduced. Afterwards, the integration of these areas, the advantages and disadvantages of using these technologies in the field of healthcare is discussed and a new system architecture is proposed.