Achieving data integrity verification for large-scale IoT data in cloud storage safely and efficiently has become one of the hot topics with further applications of Internet of Things. Traditional data integrity verification methods generally use encryption techniques to protect data in the cloud, relying on trusted Third Party Auditors (TPAs). Blockchain based data integrity schemes can successfully avoid the trust problem of TPAs, however, they have to face the problems of large computational and communication overhead. To address the issues above, we propose a Blockchain and Bilinear mapping based Data Integrity Scheme (BB-DIS) for large-scale IoT data. In our BB-DIS, IoT data is sliced into shards and homomorphic verifiable tags (HVTs) are generated for sampling verification. Data integrity can be achieved according to the characteristics of bilinear mapping in the form of blockchain transactions. Performance analysis of BB-DIS including feasibility, security, dynamicity and complexity is also discussed in detail. A prototype system of BB-DIS is then presented to illustrate how to implement our verification scheme. Experimental results based on Hyperledger Fabric demonstrate that the proposed verification scheme significantly improves the efficiency of integrity verification for large-scale IoT data with no need of TPAs.
Michael Borkowski, Marten Sigwart, Philipp Frauenthaler, Taneli Hukkinen · 5 authors
Current blockchain technologies provide very limited interoperability. Restrictions with regard to asset transfers and data exchange between different blockchains reduce the usability and comfort of users, and hinder novel developments within the blockchain space. As a first step towards blockchain interoperability, we propose the DeXTT cross-blockchain transfer protocol, which can be used to record a token transfer on any number of blockchains simultaneously in a decentralized manner. We provide a reference implementation using Solidity, and evaluate its performance. We show logarithmic scalability of DeXTT with respect to the number of participating nodes, and analyze cost requirements of the transferred tokens.
Although the blockchain-based applications are considered to be less vulnerable due to the nature of the distributed ledger, they did not become the silver bullet with respect to securing the information against different security risks. In this paper, we present a literature review on the security risks that can be mitigated by introducing the blockchain technology, and on the security risks that are identified in the blockchain-based applications. In addition, we highlight the application and technology domains where these security risks are observed. The results of this study could be seen as a preliminary checklist of security risks when implementing blockchain-based applications.
This study attempts to create a cryptocurrency classification metod and tool for reliability assessment from the point of view of investors and traders. The definition of the reliability of cryptocurrency and classification criteria is formulated. The following emphasizes how, using the support vector method, based on the available open data, it is possible to determine the reliability of Ethereum-based cryptocurrencies. As a result of testing, 15 reliable cryptocurrencies were identified and software was developed that allows you to collect and classify cryptocurrencies.
Accurate and complete educational records are a valuable asset for people. In recent years, educational records have been digitized. However, there are still two key challenges that have not been resolved. One is to achieve secure and privacy-preserving storage of educational records, while another concern how to realize the sharing of educational records and ensure the security of the sharing process. In this paper, we propose EduRSS, a blockchain-based storage and sharing scheme for educational records is proposed, which combines blockchain, storage servers, and cryptography techniques to create a reliable and safe environment. In our proposal, the blockchain technology is used to ensure the security and reliability of data storage, while the smart contracts on the blockchain are used to regulate the process of storage and sharing. More precisely, the off-chain storage servers store the original educational records in encrypted form, while the hash information of the records is stored on the blockchain. The off-chain records are anchored periodically with the hash information on the blockchain to ensure the security of data storage. Cryptography techniques are utilized to handle records encryption and messages digital signature. To assess the effectiveness of EduRSS, we designed and tested a proof of concept of this scheme. The relative security analysis shows that EduRSS is safe and has a lower computational cost than that of the CP-ABE and the MA-CPABE schemes.
In traditional electronic health records (EHRs), medical-related information is generally separately controlled by different hospitals and thus it leads to the inconvenience of information sharing. Cloud-based EHRs solve the problem of information sharing in the traditional EHRs. However, cloud-based EHRs suffer the centralized problem, i.e., cloud service center and key-generation center. This paper works on creating a new EHRs paradigm which can help in dealing with the centralized problem of cloud-based EHRs. Our solution is to make use of the emerging technology of blockchain to EHRs (denoted as blockchain-based EHRs for convenience). First, we formally define the system model of blockchain-based EHRs in the setting of consortium blockchain. In addition, the authentication issue is very important for EHRs. However, existing authentication schemes for blockchain-based EHRs have their own weak points. Therefore, in this paper, we also propose an authentication scheme for blockchain-based EHRs. Our proposal is an identity-based signature scheme with multiple authorities which can resist collusion attack out of N from N-1 authorities. Furthermore, our scheme is provably secure in the random oracle model and has more efficient signing and verification algorithms than existing authentication schemes of blockchain-based EHRs.
David Derler, Kai Samelin, Daniel Slamanig, Christoph Striecks
Blockchain technologies recently received a considerable amount of attention. While the initial focus was mainly on the use of blockchains in the context of cryptocurrencies such as Bitcoin, application scenarios now go far beyond this. Most blockchains have the property that once some object, e.g., a block or a transaction, has been registered to be included into the blockchain, it is persisted and there are no means to modify it again. While this is an essential feature of most blockchain scenarios, it is still often desirable-at times it may be even legally required-to allow for breaking this immutability in a controlled way.
Proof-of-stake blockchain protocols are becoming one of the most promising alternatives to the energy-consuming proof-of-work protocols. However, one particularly critical threat in the PoS setting is the well-known long-range attacks caused by secret key leakage (LRSL attack). Specifically, an adversary can attempt to control/compromise accounts possessing substantial stake at some past moment such that double-spend or erase past transactions, violating the fundamental persistence property of blockchain. Puncturable signatures provide a satisfying solution to construct practical proof-of-stake blockchain resilient to LRSL attack, despite of the fact that existent constructions are not efficient enough for practical deployments.
In this paper, we provide an in-depth study of puncturable signatures and explore its applications in the proof-of-stake blockchain. We formalize a security model that allows the adversary for adaptive signing and puncturing queries, and show a construction with efficient puncturing operations based on the Bloom filter data structure and strong Diffie-Hellman assumption. The puncturing functionality we desire is for a particular part of message, like prefix, instead of the whole message. Furthermore, we use puncturable signatures to construct practical proof-of-stake blockchain protocols that are resilient to LRSL attack, while previously the forward-secure signature is used to immunize this attack. We implement our scheme and provide experimental results showing that in comparison with the forward-secure signature, our construction performs substantially better on signature size, signing and verification efficiency, significantly on key update efficiency.
Antoine Durand, Emmanuelle Anceaume, Romaric Ludinard
Our work focuses on the design of a scalable permissionless blockchain in the proof-of-stake setting. In particular, we use a distributed hash table as a building block to set up randomized shards, and then leverage the sharded architecture to validate blocks in an efficient manner. We combine verifiable Byzantine agreements run by shards of stakeholders and a block validation protocol to guarantee that forks occur with negligible probability. We impose induced churn to make shards robust to eclipse attacks, and we rely on the UTXO coin model to guarantee that any stakeholder action is securely verifiable by anyone. Our protocol works against adaptive adversary, and makes no synchrony assumption beyond what is required for the byzantine agreement.
Now more and more data are being outsourced to cloud services. In order to ensure data security and privacy, data are usually stored on the cloud server in the form of ciphertext. When a user requests access to the encrypted data, an access key distributed by a third party is needed. However, if the third party is dishonest, the security of the system will be threatened. Faced with this problem, in this paper, we propose a new secure cloud storage framework with access control by using the Ethereum blockchain technology. Our new scheme is a combination of Ethereum blockchain and ciphertext-policy attribute-based encryption (CP-ABE). The proposed cloud storage framework is decentralized, that is, there is no trusted third party in the system. Our scheme has three main features. First, as the Ethereum blockchain technology is used, the data owner can store ciphertext of data through smart contracts in a blockchain network. Second, the data owner can set valid access periods for data usage so that the ciphertext can only be decrypted during valid access periods. Finally, as the creation and invocation of each smart contract can be stored in the blockchain, thus, the function of the trace is achieved. The analysis of the security and experiment shows that our scheme is feasible.
Yong Wang, Aiqing Zhang, Peiyun Zhang, Huaqun Wang
The sharing of electronic health records (EHRs) has great positive significance for research of disease and doctors' diagnosis. In recent years, cloud-based electronic medical record sharing scheme has brought a lot of conveniences, but the centralization of cloud exposes threats inevitably to data security and privacy preservation. Blockchain technology can be seen as a promising solution to address these problems on account of its unique propertis of decentration, anonymity, unforgeability and verifiability. In this paper, we propose a blockchain based secure and privacy-preserving EHR sharing protocol. Data requester can search desired keyword from data provider to find relevant EHRs on the EHR consortium blockchain and get the re-encryption ciphertext from cloud server after getting the data owner's authorization. The scheme mainly uses searchable encryption and conditional proxy re-encryption to realize data security, privacy preservation, and access control. Furthermore, proof of authorization is designed as the consensus mechanism for consortium blockchain to guarantee system's availability. Security analysis demonstrates that the proposed protocol can achieve security goals. Besides, we emulate the cryptographic primitives and implement the proposed scheme on Ethereum platform. Performance evaluation shows that the proposed scheme has high computational efficiency.
In cloud system, user identity authentication is a key problem. If design defects persist in a cloud user identity authentication scheme, direct risks of sensitive data loss and severe information breach will be incurred. At present, the main problem of cloud user identity management system is that it relies too much on third-party services. Although some third-party-detachment schemes have been proposed in recent years, most of them still rely heavily on cloud server-centered design system. In this paper, a cloud user identity management protocol based on ethereum blockchain was proposed, followed by an establishment of a simple credit management system framework. The new protocol is an improved version of CIDM (Consolidated Identity Management) referred to as EIDM (Ethrerum-based Identity Management) protocol. In the improved protocol, JWT (JSON Web Token) in OAuth 2.0 was used to introduce smart contracts into EIDM protocol, and the credit management system was added to the system so that it can provide a credible identity authentication protocol for cloud users and service providers. The new protocol solves the problem of over-reliance on third parties in the existing identity management system solutions. In the end, an analysis on the security of the new protocol showed that the EIDM protocol proposed in this paper presents more diversified security guarantees relative to the CIDM protocol. The performance evaluation results also indicated that the new protocol demonstrates better practicability and flexibility.
Communication across distributed systems, each running its own consensus, is a problem previously studied under the assumption of trust across systems. With the appearance of distributed ledgers or blockchains, numerous protocols have emerged, which attempt to achieve trustless communication between distrusting ledgers and participants. Cross-chain communication thereby plays a fundamental role in cryptocurrency exchanges, sharding, bootstrapping and extension of distributed ledgers. Unfortunately, existing proposals are designed ad-hoc for specific use-cases, making it hard to gain confidence on their correctness and to use them as building blocks for new systems.
Electronic health record (EHR) has recorded the process of occurrence, development, and treatment of diseases. So it has high medical value. Owing to the private and sensitive nature of medical data for patients, the data sharing and privacy preservation are critical issues in EHR. Blockchain technology may be a promising solution for the problems above since it holds the features of decentralization and tamper resistance. In the paper, we propose a medical data sharing and protection scheme based on the hospital’s private blockchain to improve the electronic health system of the hospital. Firstly, the scheme can satisfy various security properties such as decentralization, openness, and tamper resistance. A reliable mechanism is created for the doctors to store medical data or access the historical data of patients while meeting privacy preservation. Furthermore, a symptoms-matching mechanism is given between patients. It allows patients who get the same symptoms to conduct mutual authentication and create a session key for their future communication about the illness. The proposed scheme is implemented by using PBC and OpenSSL libraries. Finally, the security and performance evaluation of the proposed scheme is given.
A smart contract is an agreement between two or more parties, which is executed by the computer code. The code does the execution without giving either party the ability to back out, so it ensures the trustless execution. The smart contract is one of the most important features in blockchain applications, which implements trusted transactions without third parties. However, with the rapid development, blockchain smart contracts have also exposed many security problems, and some attacks caused by contract vulnerabilities have led to terrible losses. In order to better deal with such dilemma, making a comprehensive survey about the security verification of blockchain smart contracts from major scientific databases is quite indispensable. Even though the significance of studying security verification of blockchain smart contracts is evident, it is really fresh yet. The major contributions of our survey work come from three aspects. First, after retrieving all-sided research studies, we select 53 most related papers to show the state-of-the art of this topic, where 20 papers focus on dealing with security assurance of blockchain smart contracts, and 33 papers focus on the correctness verification of blockchain smart contracts. Second, we propose a taxonomy toward the topic of security verification of blockchain smart contracts and discuss the pros and cons of each category of related studies. Third, through in-depth analysis of these studies, we come to know that the correctness verification of smart contracts based on the formal method has already become the more significant and more effective method to validate whether a smart contract is credible and accurate. So, we further present representative studies of formal verification of smart contracts in detail to demonstrate that using a formal method to validate blockchain smart contracts must have a promising and meritorious future.
Dinh C. Nguyen, Pubudu N. Pathirana, Ming Ding, Aruna Seneviratne
Recent years have witnessed a paradigm shift in the storage of Electronic Health Records (EHRs) on mobile cloud environments, where mobile devices are integrated with cloud computing to facilitate medical data exchanges among patients and healthcare providers. This advanced model enables healthcare services with low operational cost, high flexibility, and EHRs availability. However, this new paradigm also raises concerns about data privacy and network security for e-health systems. How to reliably share EHRs among mobile users while guaranteeing high-security levels in the mobile cloud is a challenging issue. In this paper, we propose a novel EHRs sharing framework that combines blockchain and the decentralized interplanetary file system (IPFS) on a mobile cloud platform. Particularly, we design a trustworthy access control mechanism using smart contracts to achieve secure EHRs sharing among different patients and medical providers. We present a prototype implementation using Ethereum blockchain in a real data sharing scenario on a mobile app with Amazon cloud computing. The empirical results show that our proposal provides an effective solution for reliable data exchanges on mobile clouds while preserving sensitive health information against potential threats. The system evaluation and security analysis also demonstrate the performance improvements in lightweight access control design, minimum network latency with high security and data privacy levels, compared to the existing data sharing models.
Blockchain have been an interesting research area for a long time and the benefits it provides have been used by a number of various industries. Similarly, the healthcare sector stands to benefit immensely from the blockchain technology due to security, privacy, confidentiality and decentralization. Nevertheless, the Electronic Health Record (EHR) systems face problems regarding data security, integrity and management. In this paper, we discuss how the blockchain technology can be used to transform the EHR systems and could be a solution of these issues. We present a framework that could be used for the implementation of blockchain technology in healthcare sector for EHR. The aim of our proposed framework is firstly to implement blockchain technology for EHR and secondly to provide secure storage of electronic records by defining granular access rules for the users of the proposed framework. Moreover, this framework also discusses the scalability problem faced by the blockchain technology in general via use of off-chain storage of the records. This framework provides the EHR system with the benefits of having a scalable, secure and integral blockchain-based solution.
Matteo Franceschi, Davide Morelli, David Plans, Alan Brown · 7 authors
The problem of protecting sensitive data like medical records, and enabling the access only to authorized entities is currently a challenge. Current solutions often require trusting some centralized entity which is in charge of managing the data. The disruptive technology of blockchains may offer the possibility to change the current scenario and give to the users the control on their personal data. In this paper we propose ComeHere, a system able to store medical records and to exploit the blockchain technology to control and track the access right transfer on the blockchain. The paper shows the current status of the project, presents a preliminary proof-of-concept implementation and discusses the future improvements of the system, and some critical issues which are still open.
Shixiong Yao, Jing Chen, Kun He, Ruiying Du · 6 authors
In the recent years, the vulnerabilities of conventional public key infrastructure are exposed by the real-world attacks, such as the certificate authority’s single-point-of-failure or clients’ private information leakage. Aimed at the first issue, one type of approach is that multiple entities are introduced to assist the certificate operations, including registration, update, and revocation. However, it is inefficient in computation. Another type is to make the certificate information publicly visible by bringing in the log servers. Nevertheless, the data synchronization among log servers may lead to network latency. Based on the second approach, the blockchain-based public key infrastructure schemes are proposed. Through these type of schemes, all the certificate operations are stored in the blockchain for public audit. However, the issue of revoked certificates’ status storage is worth paying attention, especially in the setting with massive certificates. In addition, the target web server that a client wants to access is exposed in the process of certificate status validation. In this paper, we propose a privacy-preserving blockchain-based certificate status validation scheme called PBCert to solve these two issues. First, we separate the revoked certificates control and storage plane. Only the minimal control information (namely, certificate hashes and related operation block height) is stored in the blockchain and it uses external data stores for the detailed information about all revoked certificates. Second, we design an obscure response to the clients’ certificate status query for the purpose of privacy preserving. Through the security analysis and experiment evaluation, our scheme is significant in practice.
Tiago Quaini, Alex Roehrs, Cristiano André da Costa, Rodrigo da Rosa Righi
Electronic health records (EHR) are usually maintained in a centralized way by health organizations, leaving aside an integration between different health organizations to view the complete health history of a given patient. This lack of EHR integration prevents patients and physicians to have a unified view of medical records, which are often stored in different health organizations. Recent studies have proposed using Blockchain technology in distributed architectures due to its security and integration properties. In this context, this article proposes an application architecture using Blockchain technology for distributed EHR integration, which is called UniRec (Unified Medical Records). In the proposed model we seek to understand its effectivity, performance and applicability, using a case study methodology. We developed a prototype, which is evaluated using a test scenario. The prototype proved to be effective for distributed EHR integration, allowing one healthcare institution to view an EHR previously added by different providers, after being granted permission. During the test scenario execution, we obtained an average response time of 2.77 seconds, 961.6 MiB of memory consumption, 21.5% CPU usage and a total disk usage of 34.6 MB. The results reinforce the potential and feasibility of employing Blockchain for managing and storing medical data.
With the rapid development of the Internet of things (IoT), more and more IoT devices are connected and communicate frequently. In this background, the traditional centralized security architecture of IoT will be limited in terms of data storage space, data reliability, scalability, operating costs and liability judgment. In this paper, we propose an new key information storage framework based on a small distributed database generated by blockchain technology and cloud storage. Specifically, all encrypted key communication data will be upload to public could server for enough storage, but the abstracts of these data (called "communication logs") will be recorded in "IoT ledger" (i.e., an distributed database) that maintained by all IoT devices according to the blockchain generation approach, which could solve the problem of data reliability, scalability and liability judgment. Besides, in order to efficiently search communication logs and not reveal any sensitive information of communication data, we design the secure search scheme for our "IoT ledger", which exploits the Asymmetric Scalar-product Preserving Encryption (ASPE) approach to guarantee the data security, and exploits the 2-layers index which is tailor-made for blockchain database to improve the search efficiency. Security analysis and experiments on synthetic dataset show that our schemes are secure and efficient.
The idea of big data has gained extensive attention from governments and academia all over the world. It is especially relevant for the establishment of a smart city environment combining complex heterogeneous data with data analytics and artificial intelligence (AI) technology. Big data is generated from many facilities and sensor networks in smart cities and often streamed and stored in the cloud storage platform. Ensuring the integrity and subsequent auditability of such big data is essential for the performance of AI-driven data analysis. Recent years has witnessed the emergence of many big data auditing schemes that are often characterized by third party auditors (TPAs). However, the TPA is a centralized entity, which is vulnerable to many security threats from both inside and outside the cloud. To avoid this centralized dependency, we propose a decentralized big data auditing scheme for smart city environments featuring blockchain capabilities supporting improved reliability and stability without the need for a centralized TPA in auditing schemes. To support this, we have designed an optimized blockchain instantiation and conducted a comprehensive comparison between the existing schemes and the proposed scheme through both theoretical analysis and experimental evaluation. The comparison shows that lower communication and computation costs are incurred with our scheme than with existing schemes.
Internet of Things is widely used in many fields such as industry, medical care, education, and supply chain. With the participation of multi-authorized entities, a large number of dynamic data will be generated in the basic dimension of time. The operations on these data have to be safe and traceable for use in various forensics and decisions. Therefore, the key point of dynamic data security protection is to reject tampering of unauthorized users and to realize the process in evidence and tracing of the dynamic data operation. In order to find a solution to the problem above, an optimization of dynamic data traceability mechanism based on consortium blockchain is proposed in this article. First, a mathematical model for the security of dynamic data storage has been established, followed by analysis on honest behavior motive of individual node decision-making in group game and distributed node cooperation essence in specific industry background. After that, ownership transition function and the architecture of the dynamic data storage system are optimized; quality and growth characteristics of the system under stochastic state model are analyzed. Result shows that the solution can effectively avoid potential attacks such as tampering and faking under approved accession mode. The mechanism has good application value while ensuring the dynamic data storage security.
This paper addresses the problem of uploading large quantities of sensitive industrial data to a public distributed network by proposing a new framework. The framework combines the existing technologies of the distributed web and distributed ledger to provide a mechanism of encrypting data and choosing whom to share the data with. The framework is designed to work with existing platforms; the InterPlanetary File System (IPFS) and the Ethereum blockchain platforms are used as examples within this paper, though it is stated that similar platforms are capable of providing the requirements for the framework to operate. The framework uses the concept of the Diffie-Hellman Key Exchange (DHKE), and is implemented in three different mechanisms of the DHKE: one-step Elliptical-Curve Diffie-Hellman Key Exchange (ECDH); two-step ECDH; and Supersingular Isogeny Diffie-Hellman Key Exchange (SIDH). The paper discusses the security of each along with individual advantages and disadvantages, and concludes that the SIDH is the most appropriate implementation for future use due to it being post-quantum secure.