Rongli Gai, Xiaoyan Du, Shuya Ma, Na Chen · 5 authors
Abstract Blockchain is an emerging distributed database technology. It has the characteristics of decentralization, non-tampering, traceability and final consistency. Blockchain can solve data management problems in untrusted environments. Based on the research and analysis of the blockchain system, this article expounds the application of the blockchain system in the distributed database environment. First, this article introduces the concept of the blockchain system and the classification of the blockchain system from multiple aspects. Then it introduces the data storage technology and data encryption technology adopted by the blockchain system in detail. Finally, the application prospects of the blockchain system in today’s society are introduced.
Dinh C. Nguyen, Pubudu N. Pathirana, Ming Ding, Aruna Seneviratne
Blockchain and Mobile Edge Computing (MEC) are newly emerging technologies with great potential to revolutionize healthcare. This paper proposes a new decentralized healthcare architecture for distributed Electronic Medical Records (EMRs) sharing among federated hospitals based on blockchain and MEC. Unlike the existing schemes that often rely on a third-party for healthcare management, we focus on a fully decentralized access control solution by using smart contracts that enable EMRs access verification at the edge of the network without requiring any central authority. Moreover, a decentralized interplanetary file system (IPFS) platform is also integrated with smart contracts over the MEC network, which significantly reduces data retrieval latency and enhances security for EMRs sharing. The experimental results and analysis show the superior performance of the proposed scheme over the existing ones in terms of reduced data retrieval latency, enhanced blockchain performance, and security guarantees.
Proof-of-work (PoW) based blockchain protocols, are protocols that organize data into blocks, connected through the use of a hash function to form chains, and which make use of PoW to reach agreement, i.e., proofs that require spending some amount of computational power to be generated. This type of protocols rose into prominence with the advent of Bitcoin, the first protocol that provably implements a distributed transaction ledger against an adversary that controls less than half of the total computational power in the network, in a setting where protocol participants join and leave dynamically without the need for a registration service. Protocols in this class were also the first to be shown sufficient to solve consensus under similar conditions, a problem of fundamental importance in distributed computing. In this thesis, we explore foundational issues of PoW-based blockchain protocols that mainly have to do with the assumptions required to ensure their safe operation. We start by examining whether a common random string that is shared at the start of the protocol execution among the protocol participants is required to efficiently run such protocols. Bitcoin's security is based on the existence of such a string, called the genesis block. On the other hand, protocols found in previous works that do not assume such a setup are inefficient, in the sense that their round complexity strongly depends on the number of protocol participants. Our first contribution is the construction of efficient PoW-based blockchain protocols that provably implement a distributed ledger and consensus without such setup. Next, we turn our attention to the PoW primitive. All previous analyses model PoW using a random oracle. While satisfactory as a sanity check, the random oracle methodology has received significant criticism and shown not to be sound. We make progress by introducing a non-idealized security model and appropriate computational assumptions that are sufficient to implement a distributed ledger or consensus when combined with the right PoW-based protocol. Finally, we analyze GHOST, a recently proposed blockchain protocol, and prove its security against a byzantine adversary under similar assumptions as Bitcoin. Previous works only considered specific attacks.
Mbarek Marwan, Abdelkarim Ait Temghart, Fatima Sifou, Feda AlShahwan
The integration of cloud computing and Internet of Things (IoT) offers a promising, rich platform for data collection and analysis in smart healthcare. In such a model, IoT devices collect data about patient health status through multiple intelligent sensors, whereas cloud offers scalable resources to quickly meet workload demands. Despite these remarkable improvements, the current architectures do not sufficiently address the security needs for patient medical records. In this perspective, and bearing in mind the specific characteristics of each technology, we propose a distributed security mechanism in a way that fits with IoT and cloud constraints. Our contribution to secure cloud-enabled IoT is twofold. First, we rely on OM-AM (Objective, Model, Architecture and Mechanism) for modeling and analysing the security and privacy requirements of smart healthcare. Second, we use blockchain architecture along with Attribute-Based Access Control (ABAC) model as a decentralized flexible system to support access control decisions. In particular, we rely on XACML (eXtensible Access Control Markup Language) to easily build and implement robust policies required for maintaining a secure IoT-based environment. The novelty of the proposed framework lies at smartly leveraging the recent technologies to keep health information confidential. In fact, putting blockchain and IoT together would undoubtedly create a totally new solution for remote patient monitoring. The simulation results show that the proposal is an efficient way of implementing ubiquitous and cognitive tools for smart healthcare systems.
In the cryptocurrency era, Blockchain is one of the expeditiously growing information technologies that help in providing security to the data. Data tampering and authentication problems generally occur in centralized servers while sharing and storing the data. Blockchain provides the platform for big data and cloud storage in enhancing the security by evading from pernicious users. In this paper, we have discussed the exhaustive description of blockchain and its need, features and applications. Analysis of blockchain is done for different domains such as big data, cloud, internet of things and mobile cloud where the differences V’s are compared with big data and blockchain. SWOT (Strength Weakness Opportunities Threats) analysis is performed to address the merits and limitations in blockchain technology. The survey in aspects of data security, data storage, data sharing and data authentication through blockchain technology is done and the challenges are discussed to overcome the problem that leads in big data and cloud storage. The detailed comparative analysis proves that the blockchain technology overcomes the problems in big data storage and data security in cloud.
The General Purpose Atomic Crosschain Transaction protocol allows composable programming across multiple Ethereum blockchains. It allows for inter-contract and inter-blockchain function calls that are both synchronous and atomic: if one part fails, the whole call execution tree of function calls is rolled back. The protocol operates on existing Ethereum blockchains without modification. It works for both public permissioned and consortium blockchains. Additionally, the protocol is expected to work across heterogeneous blockchains other than Ethereum. This paper describes the protocol, analyses it in terms of Gas usage and Finalised Block Periods for three scenarios: reading a value from one blockchain to another, writing a value from one blockchain to another, and a trade finance system involving five contracts on five blockchains with a complex call execution tree, and provides an initial security analysis that shows that the protocol has Safety and Liveness properties.
Blockchain technology has a wide scope of applicability for accounting and auditing purposes, separate from Bitcoin or other cryptocurrencies. However, although blockchain technology is identified as a popular topic within the field, there currently exists a lack of consensus on how it will be realistically applied. This paper aims to map the presently existing international auditing literature and offer clarity to an otherwise heterogeneous field. The mapping analysis will aid in examining the underlying theme employed within studies. Through the use of the Bibliometrix R-Package "Biblioshiny", a sample of 112 studies were downloaded from the Web of Science Core Collection and analyzed. This study's results show that the topic has gained increased international popularity and separated into distinct research streams; Encrypted Private and Secure Information Sharing, Distributed Ledger, Smart Contracts, Continuous Audit, Audit Trail and Tokenization. However, there still exists a research gap that must be addressed to hasten the adoption of blockchain technology in auditing.
Nov 23, 2020·The international archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences
Kazım Onur TOKA, Yılmaz Dikilitaş, Talha Oktay, Ahmet Sayar
Abstract. IoT is becoming ubiquitous in industry, homes, cities, literally in every aspect of our daily lives. Securing IoT-based systems is difficult because of deficiencies in the very nature of IoT devices such as limited battery power, processing, and storage, etc. Blockchain is a new approach used to securely record transactions and offers potential solutions to computer and internet security issues such as confidentiality, integrity, availability, authentication, authorization, and accountability. Blockchain, as a decentralized ledger consisting of interconnected blocks, can remedy most of the security deficiencies of heavily IoT based systems. The Hyperledger Fabric blockchain network used in this study provides confidentiality, data integrity, authentication, and data security for data obtained from IoT devices. Widely used IoT data transfer MQTT protocol is included in the proposed approach. The approach is demonstrated in a simple demo Hyperledger network with simulated IoT devices. The proposed approach is discussed in terms of network security dimensions. Based on the features of the Hyperledger Blockchain network, it is displayed that the IoT security deficiencies can largely be remedied with the proposed approach.
ML-as-a-service (MLaaS) becomes increasingly popular and revolutionizes the lives of people. A natural requirement for MLaaS is, however, to provide highly accurate prediction services. To achieve this, current MLaaS systems integrate and combine multiple well-trained models in their services. Yet, in reality, there is no easy way for MLaaS providers, especially for startups, to collect sufficiently well-trained models from individual developers, due to the lack of incentives. In this article, we aim to fill this gap by building up a model marketplace, called as Golden Grain, to facilitate model sharing, which enforces the fair model-money swapping process between individual developers and MLaaS providers. Specifically, we deploy the swapping process on the blockchain, and further introduce a blockchain-empowered model benchmarking process for transparently determining the model prices according to their authentic performances, so as to motivate the faithful contributions of well-trained models. Especially, to ease the blockchain overhead for model benchmarking, our marketplace carefully offloads the heavy computation and designs a secure off-chain on-chain interaction protocol based on a trusted execution environment (TEE), for ensuring both the integrity and authenticity of benchmarking. We implement a prototype of our Golden Grain on the Ethereum blockchain, and conduct extensive experiments using standard benchmark datasets to demonstrate the practically affordable performance of our design.
Christian Rondanini, Barbara Carminati, Federico Daidone, Elena Ferrari
Nowadays, organizations need to set higher and higher business goals in order to cope with market requirements. Indeed, a widespread strategy for organizations is to join in inter-organizational processes, which set collaborations and resource sharing among involved organizations. However, the possible lack of trust among the organizations poses relevant issues on the processing of sensitive resources. A promising approach to cope with this issue is leveraging on blockchain technology. Thanks to its design and consensus algorithm, blockchain provides a trustworthy infrastructure that allows partners involved in the collaboration to monitor and perform audits on the workflow transitions. In general, the focus of the existing blockchain-based workflow management solutions is mainly workflow coordination. However, a challenging characteristic of some workflows is that they require the exchange of a big amount of data that has to be managed off-chain, that is, directly exchanged between data producer and consumer. This off-chain data sharing should be secured and controlled such to follow the workflow execution.To cope with this challenge, in this paper, we propose a controlled information sharing in inter-organizational workflows enforced via smart contracts. Smart contracts are designed to coordinate the workflow execution, as well as to deploy a set of authorizations granting access only to the task executor and only to those resources needed for task execution and only during the task activation. We have also run a set of experiments to show the feasibility of our approach.
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.
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.
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.
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.
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.
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.
In the cloud storage applications, the cloud service provider (CSP) may delete or damage the user’s data. In order to avoid the responsibility, CSP will not actively inform the users after the data damage, which brings the loss to the user. Therefore, increasing research focuses on the public auditing technology recently. However, most of the current auditing schemes rely on the trusted third public auditor (TPA). Although the TPA brings the advantages of fairness and efficiency, it cannot get rid of the possibility of malicious auditors, because there is no fully trusted third party in the real world. As an emerging technology, blockchain technology can effectively solve the trust problem among multiple individuals, which is suitable to solve the security bottleneck in the TPA-based public auditing scheme. This paper proposed a public auditing scheme with the blockchain technology to resist the malicious auditors. In addition, through the experimental analysis, we demonstrate that our scheme is feasible and efficient.
The future of multi-blockchain architecture depends on the emergence of new protocols that achieve communication between trustless cross-chain participants. However, interoperability between blockchains remains an open problem. Existing approaches provide integration through solutions using a middleware system, which makes it harder to gain confidence mainly in terms of security and correctness of the process. A cross-chain protocol needs to provide a self-verifiable state-proof that embeds trust in the transfer process. We propose a Burn-to-Claim cross-chain protocol to seamlessly exchange assets between networks. Our scheme transfers assets from one blockchain system to another in a way that the asset is burned from the source blockchain and claimed on the destination blockchain. Our mechanism employs combinations of crypto mechanisms such as digital signatures and time lock to operate the protocol in a distributed manner. We provide an analysis which proves that our cross-chain protocol transfers assets correctly and securely.
During the Coincheck incident, which recorded the largest damages in cryptocurrency history in 2018, it was demonstrated that using Mosaic token can have a certain effect. Although it seems attractive to employ tokens as countermeasures for cryptocurrency leakage, Mosaic is a specific token for the New Economy Movement (NEM) cryptocurrency and is not employed for other blockchain systems or cryptocurrencies. Moreover, although some volunteers tracked leaked NEM using Mosaic in the CoinCheck incident, it would be better to verify that the volunteers can be trusted. Simultaneously, if someone (e.g., who stole cryptocurrencies) can identify the volunteers, then that person or organization may be targets of them. In this paper, we propose an anonymous trust-marking scheme on blockchain systems that is universally applicable to any cryptocurrency. In our scheme, entities called token admitters are allowed to generate tokens adding trustworthiness or untrustworthiness to addresses. Anyone can anonymously verify whether these tokens were issued by a token admitter. Simultaneously, only the designated auditor and no one else, including nondesignated auditors, can identify the token admitters. Our scheme is based on accountable ring signatures and commitment, and is implemented on an elliptic curve called Curve25519, and we confirm that both cryptographic tools are efficient. Moreover, we also confirm that our scheme is applicable to Bitcoin, Ethereum, and NEM.
Blockchain technology is increasingly being considered among both private enterprises and public services. However, it poses a challenge with regard to aligning its identity management scheme with the Public Key Infrastructure and the Qualified Digital Certificates issued by Qualified Trust Service Providers. To solve this challenge, we will present a solution in the form of an architecture reference model, which enables enterprises and public services to leverage blockchain technology by integrating Qualified Electronic Signatures with blockchain transactions. The evaluation of the architecture reference model is provided through the design of a Blockchain-based Trusted Public Service and a use-case scenario example. The proposed architecture reference model is based on the CEF building blocks EBSI, eSignature, and eID compliant with eIDAS.
Shee-Ihn Kim, Seung‐Hee Kim, Seung‐Hee Kim, Seung‐Hee Kim
Abstract The current e-commerce payment systems for credit or check cards require a payment gateway (PG). This incurs PG fees, which in turn increases the cost of engaging in e-commerce. This paper proposes a simple payment model that uses basic cryptocurrency features, such as public key, private key, and digital signature, to eliminate the need for transaction intermediaries such as public key certificate and PG. This model can process e-commerce payments without registering additional public key certificate, public key, or private key. The use of a digital signature guarantees the integrity and nonrepudiation of electronic payments, besides eliminating the fees for intermediary services such as PG, thereby reducing the overall cost of operating e-commerce services. This proposal is crucial as it is the first attempt to apply blockchain technology to e-commerce payment services. In addition, our model is important because it not only supports the evolution of e-commerce payment technology but also enhances the competitive advantage of using e-commerce.
William Pourmajidi, Lei Zhang, John Steinbacher, Tony Erwin · 5 authors
Service Level Agreements (SLA) are employed to ensure the performance of Cloud solutions. When a component fails, the importance of logs increases significantly. All departments may turn to logs to determine the cause of the issue and find the party at fault. The party at fault may be motivated to tamper with the logs to hide their role. We argue that the critical nature of Cloud logs calls for immutability and verification mechanism without the presence of a single trusted party. This article proposes such a mechanism by describing a blockchain-based log storage system, called Logchain, which can be integrated with existing private and public blockchain solutions. Logchain uses the immutability feature of blockchain to provide a tamper-resistance platform for log storage. Additionally, we propose a hierarchical structure to address blockchains’ scalability issues. To validate the mechanism, we integrate Logchain into Ethereum and IBM Blockchain. We show that the solution is scalable and perform the analysis of the cost of ownership to help a reader select an implementation that would address their needs. The Logchain's scalability improvement on a blockchain is achieved without any alteration of blockchains’ fundamental architecture. As shown in this work, it can function on private and public blockchains and, therefore, can be a suitable alternative for organizations that need a secure, immutable log storage platform.
João Henrique Faes Battisti, Maurício A. Pillon, Guilherme Koslovski, Charles C. Miers
A considerable number of electronic transaction systems employ classicapproaches based on centralized trust mechanisms, not exploitingthe latest technological advances. Alternatively, the concept ofblockchain stands out, elaborated without the need for this centralizedtrust, but rather dependent on securely chained technologies in whichthe elements involved can conduct secure negotiations. Blockchain isdesigned to address security and distributed system issues through theuse of encryption, algorithms, P2P networks, and consensus mechanisms.This paper presents a Denial of Service (DoS) security analysisof the more traditional Practical Byzantine Fault Tolerance (PBFT)and Proof of Work (PoW) consensus mechanisms available onMultichain and Ethereum solutions based on a private / consortiumblockchain scenario. We present our results of a controlled DoSattack, revealing the importance and need for security-relatedanalysis of blockchain implementations of private / consortiumblockchains.