Multi-stakeholder and organizational involvement is an integral part of the medicine supply chain. Keeping track of the activities associated with medical products is difficult when the system is complex. Their complexity limits transparency and data provenance. Deficiencies within existing supply chains result in the counterfeiting of drugs, illegal imports, and inefficient operations. Due to these limitations, product integrity is compromised, resulting in product wastage. Visibility of the entire product supply chain is crucial for the pharmaceutical industry in terms of product safety and reduction of manufacturing costs. The Cloud-based Blockchain-powered architecture of the system provides a platform for addressing the need of pharma-material traceability, data storage, privacy of data, and quality assurance. This framework comprises of the identification of activities through tagging, information sharing in a secure environment; cloud-based storage using an off-chain Interplanetary File System (IPFS) and an on-chain couch DB; and access to this information that is controlled by the system's regulator. Electronic drug records will be accessed via a smart contract in Hyperledger Blockchain. The system assists in identifying false and cross-border products through the manufacturer and country of origin. A scan will identify counterfeit medications, showing that they are unauthorized products which may pose a risk to patients. Our experiments demonstrated the efficiency and usability of the design platform. Finally, we benchmarked the system using Hyperledger Caliper.
Currently there exist many blockchains with weak trust guarantees, limiting applications and participation. Existing solutions to boost the trust using a stronger blockchain, e.g., via checkpointing, requires the weaker blockchain to give up sovereignty. In this paper, we propose a family of protocols in which multiple blockchains interact to create a combined ledger with boosted trust. We show that even if several of the interacting blockchains cease to provide security guarantees, the combined ledger continues to be secure - our Trustboost protocols achieve the optimal threshold of tolerating the insecure blockchains. This optimality, along with the necessity of blockchain interactions, is formally shown within the classic shared memory model, tackling the long standing open challenge of solving consensus in the presence of both Byzantine objects and processes. Furthermore, our proposed construction of Trustboost simply operates via smart contracts and require no change to the underlying consensus protocols of the participating blockchains, a form of "consensus on top of consensus''. The protocols are lightweight and can be used on specific (e.g., high value) transactions; we demonstrate the practicality by implementing and deploying Trustboost as cross-chain smart contracts in the Cosmos ecosystem using approximately 3,000 lines of Rust code, made available as open source [52]. Our evaluation shows that using 10 Cosmos chains in a local testnet, Trustboost has a gas cost of roughly $2 with a latency of 2 minutes per request, which is in line with the cost on a high security chain such as Bitcoin or Ethereum.
Amirmohammad Pasdar, Young Choon Lee, Zhongli Dong
A blockchain is a form of distributed ledger technology where transactions as data state changes are permanently recorded securely and transparently without the need for third parties. Besides, introducing smart contracts to the blockchain has added programmability, revolutionizing the software ecosystem toward decentralized applications. Although promising, the usability of smart contracts is primarily limited to on-chain data without access to the external systems (i.e., off-chain) where real-world data and events reside. This connectability to off-chain data for smart contracts and blockchain is an open practical problem referred to as the “oracle problem” and is defined as how real-world data can be transferred into/from the blockchain. Hence, Blockchain oracles are introduced and implemented in the form of application programming interfaces connecting the real world to the blockchain for mitigating such a limitation. This article studies and analyzes how blockchain oracles provide final feedback (i.e., outcome) to smart contracts and survey blockchain oracle technologies and mechanisms regarding data integrity and correctness. Since the existing solutions are extensive in terms of characteristics and usage, we investigate their structure and principles by classifying the blockchain oracle implementation techniques into two major groups voting-based strategies and reputation-based ones. The former mainly relies on participants’ stakes for outcome finalization, while the latter considers reputation and performance metrics in conjunction with authenticity-proof mechanisms for data correctness and integrity. We present the result of this classification with a thorough discussion of the state of the art and provide the remaining challenges and future research directions in the end.
Sangeeta Narayan, Abdul Mateen, Jae Won Jeong, Seung Yeob Nam
CCTV cameras and black boxes in vehicles play an important role in road condition and accident management. CCTV laws require that data recorded by CCTV cameras be kept securely and only authorized people have access to it. CCTV footage and blackbox data are saved locally to the camera's microSD card, a separate hard drive, or the cloud. Security and data integrity are issues with both local and cloud storage. In this paper, we propose an IPFS and blockchain-based Decentralized Storage Application that stores files in a decentralized way. The proposed scheme is implemented using the private Ethereum blockchain, Smart Contacts, and IPFS.
Our proposed scheme is modified from that of Camenisch et al., yet achieves more efficient than their scheme. In general, a batch verification method is more advantageous and is also able to save more cost than the original scheme, while non-interactive zero knowledge proof requires fewer communication rounds than interactive zero knowledge proof. The proposed scheme employs the simplified small exponents test method for secure and fast batch verification on multiple signature elements, which can remarkably reduce the number of time-consuming pairing operations required by both a prover and a verifier, resulting in greatly improved computational efficiency. By applying non-interactive zero knowledge proof technique, the proposed scheme also decreases the number of communication rounds required between both of them.
Recently, global healthcare has made great progress with the use of Internet of Things technology. However, for there to be excellent patient care, there must be a high degree of safety for the IoT health system. There has been a massive increase in hacking systems and the theft of sensitive and highly confidential information from large health centers and hospitals. That is why establishing a highly secure and reliable healthcare system has become a top priority. In this paper, a security scheme for the IoT-enabled healthcare environment, LBSS, is proposed. This security scheme comprises three security mechanisms. The first mechanism is based on the blockchain technology and is used for transaction integrity. The second mechanism is used to store the healthcare system data in a secure manner through the distribution of its data records among multiple servers. The third mechanism is used to access the healthcare data after applying a proposed authorization test. To minimize the security overhead, the healthcare data is prioritized in regard to its importance. Therefore, each security mechanism has specific steps for each level of data importance. Finally, the NS3 package is used to construct a simulation environment for IoT-enabled healthcare systems to measure the proposed security scheme performance. The simulation results proved that the proposed healthcare security scheme outperformed the traditional models in regard to the performance metrics.
In this study, we demonstrate that blockchain is an efficient secret-free immutable storage system that guarantees not only the integrity of data but also the integrity of the smart contract and its execution results (i.e., transaction receipt) without a secret key. In short, blockchains eliminate the need for secret key management by storage managers. For example, the secure storage of non-fungible token (NFT) history on a blockchain can also be achieved without the secret key of the NFT marketplace
Blockchain Technology Applications and Security
Cloud Data Security Solutions
Advanced Steganography and Watermarking Techniques
Bruno Bradach, Juan J. Nogueira, Guzmán Llambías, Laura González · 5 authors
During the last years, interoperability has become one of the main challenges within blockchain research as blockchains increasingly require integration between each other. Indeed, blockchains work by design in silos of information as interoperability is not a native feature. The main efforts in the field target permissionless blockchains, such as Bitcoin and Ethereum. However, interoperability in permissioned blockchains remains as an almost untouched area of work as they introduce additional requirements focusing on privacy and identity. Although there are some interoperability solutions for permissioned blockchains, they are either high-level design proposals not providing concrete implementations or focus on interoperability issues between business applications and blockchain platforms. In this paper we propose a gateway-based platform-to-platform interoperability solution for permissioned blockchains, which comprises a detailed solution design and a reference implementation. The proposal was assessed through the development of a social security case scenario, based on the reference implementation and using two blockchain platforms: Hyperledger Fabric and Corda.
Yang Shi, Junqing Liang, Mianhong Li, Tianchen Ma · 7 authors
The threshold digital signature technique is important for decentralized finance (DeFi) applications such as asset custody and cross-chain interoperations. The Edwards-curve digital signature algorithm (EdDSA) is widely used in blockchains, e.g., Libra/Diem; however, no suitable threshold solution exists. Therefore, to bridge this gap, we propose a threshold EdDSA that allows n parties to generate keys in a decentralized and distributed manner. Any t + 1-of-n parties can generate standard EdDSA signatures. This scheme supports an arbitrary threshold (t, n) and has been proven to be secure against at most t malicious adversaries. The theoretical analysis (computation complexity and communication footprints) and experimental results demonstrate that the proposed scheme performs efficiently on cloud servers and embedded devices. Furthermore, the proposed scheme is integrated with Tendermint, a blockchain framework that uses EdDSA, to generate keys and sign transactions in a decentralized manner, which indicates that this scheme is compatible with blockchains for supporting DeFi applications.
Cloud computing can provide users with sufficient computing resources, storage, and bandwidth to meet their needs. Data security and privacy protection are among the new threats faced by users. Searchable encryption is the combination of search technology and encryption technology. Searchable encryption can upload the user’s data to the cloud server after special encryption, and can realize the function of retrieving according to keywords. Comparatively to symmetric searchable encryption (SSE), public key searchable encryption (PEKS) simplifies key management greatly. However, most existing public key authenticated encryption with keyword search (PAEKS) schemes are based bilinear pairing, making them computationally expensive. Apart from this, complex retrieval requirements and the integrity of the results had not been considered. To address these problems, we propose a blockchain-based PAEKS schemes supporting multi-keyword queries and integrity verification. In addition, we provide security proofs for the PAEKS scheme under the decisional oracle Diffie-Hellman (DODH) assumption. This scheme a scheme that requires less storage and computational power than other schemes of the same kind.
Ulysse Pavloff, Yackolley Amoussou-Guenou, Sara Tucci-Piergiovanni
Ethereum has undergone a recent change called \textit{the Merge}, which made Ethereum a Proof-of-Stake blockchain, shifting closer to BFT consensus. Ethereum, which wished to keep the best of the two protocol designs (BFT and Nakomoto-style), now has a convoluted consensus protocol as its core. The result is a blockchain being possibly produced in a tree-like form while participants try to finalize blocks. We categorize different attacks jeopardizing the liveness of the protocol. The Ethereum community has responded by creating patches against some of them. We discovered a new attack on the patched protocol. To support our analysis, we propose a new high-level formalization of the properties of liveness and availability of the Ethereum blockchain, and we provide a pseudo-code. We believe this formalization to be helpful for other analyses as well. Our results yield that the Ethereum Proof-of-Stake has safety but only probabilistic liveness. The probability of the liveness is influenced by the parameter describing the time frame allowed for validators to change their mind about the current main chain.
Permission delegation has become a new way for data sharing by delegating the authorized permission to other users. A flexible authorization model with strict access control policies is promising for electronic health record (EHR) sharing with security. In this paper, a blockchain-based multi-hop permission delegation scheme with controllable delegation depth for EHR sharing has been presented. We use the interplanetary file system (IPFS) for storing the original EHRs. Smart contracts and proxy re-encryption technology are implemented for permission delegation. In order to ensure data security, we use attribute-based encryption to provide fine-grained access control. Additionally, blockchain is used to achieve traceability and immutability. We deploy smart contracts so that the delegation depth can be set by delegators. Security analysis of the proposed protocol shows that our solution meets the designed goals. Finally, we evaluate the proposed algorithm and implement the scheme on the Ethereum test chain. Our scheme outperforms the competition in terms of performance, according to the results of our experiments.
Iman Ajaj Naje, Vinod Kumar Shukla, Deepa Gupta, D.B. Ojha
Cloud computing is the collection of computing services available through the internet. ICloud virtual services are provided to the user through data centres around the world via the internet. It is currently the base of most Internet applications. Email, web engines, interpersonal organizations, web-based media, and different administrations are currently facilitated in “the cloud”. The accelerated growth in this field by both private and public sectors globally has heightened the cyberattacks on stored user data. While cost and usability are the primary advantages of cloud computing, trust and security are the two top worries of clients of cloud administrations. Blockchain is known as Distributed Ledger Technology (DLT). It is an unalterable and transparent digital ledger that uses decentralization and cryptography for security and authentication. It is the future of security and privacy improvements in the IT industry as it provides integrity, authenticity, and confidentiality to all stored data. This paper attempts to understand the root cause of cloud security attacks along with a proposed solution using blockchain technology and various cryptographic algorithms.
Jena Catherine Bel D, C Esther, Zionna Sen G B, D Tamizhmalar · 6 authors
A cloud-based repository is the most popular option for individuals and businesses to share data digitally. To move and store the data, conventional cloud hosting has come to rely on big storage providers functioning as reliable intermediaries. Although cloud providers offer robust security measures, rising usage and demand have made these centralized platforms prime targets for security breaches and hackers. This research study proposes a blockchain-based public key cryptosystem data protection scheme to address the problem. All of the data is automatically encrypted using the homomorphic technique. The ciphertext index Ci is created via a public key accessible crypto technique and set aside in the blockchain. At the same time, confidential information is protected and published in a cloud storage server. A reliable verification cloud server is used to access and manage data across users. The blockchain automatically syncs data transactions, which is more equitable to protect the confidentiality and integrity of the shared data process. In the case of numerous users, the integration of distributed ledger technology and a dedicated cloud verification server makes it easier to implement a fair and reliable access control system. Finally, the authentication process and performance evaluation demonstrate the schemes ensure the efficiency.
Sahilpreet Singh Sidhu, Minh Nam Hai Nguyen, Chikamnaele Ngene, Sara Rouhani
Despite advances in developing various blockchain platforms and services, disparate blockchain networks do not support direct communications, causing fragmentation and data and asset in silos. Blockchain interoperability is a solution that allows communication between different blockchain platforms to exchange data and assets. This study investigates a blockchain interoperability solution based on publish-subscribe architecture to share data between various blockchain platforms. We extend the solution by providing decentralized identifiers and verifiable credentials to the users sharing and accessing data through inte-gration with Hyperledger Indy, Aries, and Ursa stack projects, which are blockchain services offering decentralized identity. We also designed a testbed comprising multiple permissioned blockchain platforms integrated with decentralized identity ser-vices to evaluate the proposed system's security and integrity
(English) Invoice factoring has been a popular way to provide cash flow for businesses. The primary function of a factoring system is to prevent an invoice from being factored twice. In order to prevent double factoring, many factoring ecosystems use one or several centralized entities to register factoring agreements. However, this puts a lot of power in the hands of these centralized entities and makes it difficult for users to dispute situations in which factoring data is unavailable, wrongly recorded or manipulated by negligence or on purpose. This thesis presents our research around the current problems of invoice factoring and our new solutions to solve this process using the blockchain technology. A public blockchain can keep a permanent, secure, ordered and transparent record of transactions which are then available for everyone at any time to view and verify. In this thesis, we start proposing a base solution, and we gradually enhance it. In the base protocol, we propose an architecture for invoicing registration based on a general blockchain. The blockchain platform builds trust between the parties by executing transactions correctly. We employed a smart contract to complete the registration process, and prevent double factoring. The smart contract provides for auditing and dispute resolution in such a way that privacy is protected and relevant information is always available. In the second protocol, we add a relayer to our architecture for easier on-boarding. Only the relayer is required to submit blockchain transactions, and pay the corresponding fees. Other participants can proxy their transactions through the relayer, and pay the relayer in fiat money. We also enhance our identity management and authentication using the concept of verifiable credentials (VC) in order to better comply with the Know-Your-Customer (KYC) regulation. In fact, in this architecture, participants use their decentralized identifiers (DIDs) and the DIDComm protocol for asynchronous and secure off-chain interactions. In the final protocol, we greatly enhance our smart contract with respect to the conditions it checks before registering an invoice factoring. We integrate non-interactive zero-knowledge proofs and cryptographic commitments into our solution. With these cryptographic tools in place, we can prevent a special type of denial of service (DoS) attack and better verify invoice details without compromising privacy. Our protocols are very efficient in terms of blockchain costs. In particular, we only need one transaction to register an invoice factoring, and most of the details are recorded in low-cost blockchain storage. Our evaluations and comparison with the literature reveals that our protocols are superior to the related works with respect to efficiency, security, privacy, and ease of use. (Català) La venda de factures o "invoice factoring" ha estat una forma popular de proporcionar flux de caixa a les empreses. La funció principal d'un sistema de venda de factures és evitar que una factura sigui venuda dues vegades. Per evitar la doble venda, molts ecosistemes de factoring utilitzen entitats centralitzades per registrar els acords de venda de factures. Això, però, posa molt poder en mans d'aquestes entitats centralitzades i dificulta que els usuaris puguin impugnar o rebatre situacions en què les dades de venda no estan disponibles, es registren erròniament o es manipulen ja sigui per negligència o a propòsit. Aquesta tesi presenta la nostra recerca al voltant dels problemes actuals dels sistemes de registre de venda de factures i les nostres novedosses solucions per resoldre aquest procés utilitzant la tecnologia "blockchain" (cadena de blocs). Mitjançant una blockchain pública es pot mantenir un registre permanent, segur, ordenat i transparent de transaccions que estan disponibles per a tothom en qualsevol moment per poder ser observades i verificades. A la tesi, comencem proposant una solució base i la anem ampliant i millorant gradualment. La primera proposta és un protocol que utilitza una arquitectura amb blockchain. La plataforma blockchain genera confiança entre les parts ja que garanteix la correcta execució de les transaccions. En aquest sentit, fem servir un contracte intel·ligent per completar el procés de registre i evitar la doble venda. El contracte intel·ligent permet l'auditoria i la resolució de disputes de manera que protegim la privadesa i fem que la informació rellevant estigui sempre disponible. Al segon protocol, afegim un "relay" o retransmissor a la nostra arquitectura per facilitar la incorporació d'usuaris al sistema. El retransmissor és l'únic que envia transaccions a la cadena de blocs i el que paga les taxes corresponents. Els altres participants poden delegar l'enviament de les seves transaccions al repetidor i pagar amb diners fiduciaris. En aquesta proposta també millorem la gestió de la identitat i de l'autenticació utilitzant el concepte de credencials verificables (Verifiable Credentials o VC) per complir millor amb la normativa "Conegui el seu client" (Know Your Customer o KYC). De fet, en aquesta arquitectura, els participants utilitzen els seus identificadors descentralitzats (Decentralized Identifier o DID) i el protocol DIDComm per a les interaccions asíncrones i segures fora de la cadena. Al protocol final, millorem en gran mesura el nostre contracte intel·ligent pel que fa a les condicions que comprova abans de registrar una venda de factura. En aquesta última solució, integrem proves no interactives de coneixement nul (Zero Knowledge Proofs o ZKP) i compromisos criptogràfics. Amb aquestes eines, podem evitar un tipus especial d'atac de denegació de servei (Denial of Service o DoS) i verificar millor els detalls de les factures sense comprometre la privadesa. Els nostres protocols són molt eficients en termes de cost per comissions. En particular, només necessitem una transacció per registrar una factura i la majoria dels detalls es registren a l'emmagatzematge de la cadena de blocs de baix cost. Les nostres avaluacions i la comparació amb la literatura revelen que els nostres protocols són superiors als treballs relacionats pel que fa a l'eficiència, la seguretat, la privadesa i facilitat d'ús.
The purpose of this paper is to present the main focus areas in smart contracts securing and to propose a procedure and a sample audit plan of an upload/download files smart contract on a blockchain-based platform designed for data and information sharing. Smart contracts and blockchain oracles definition and types are discussed and summarized. The smart contracts and blockchains securing issues and activities are systemized in four directions: code writing, security and penetration testing, blockchain security testing and vulnerability scanning tools. A five-step smart contract audit plan is suggested, adopted to the smart contract’s current functional specifications and program code complexity. The audit plan is illustrated by example.
With the development of Blockchain technology, permissioned Blockchains are getting more and more attention from researchers because applications based on permissioned Blockchains are more practical and easier to be carried out. This paper aims to design a dedicated consensus protocol for permissioned Blockchains. The existing consensus protocols applied to permissioned Blockchains are either derived from public Blockchains such as Proof of Work (PoW) or Proof of Stake (PoS), with full decentralization, resulting in low transaction processing efficiency; or derived from traditional Byzantine fault-tolerant (BFT) consensus protocols such as Practical BFT (PBFT) or HoneyBadgerBFT, with high communication complexity of the consensus process, resulting in low scalability. Therefore, we propose a dedicated consensus protocol for permissioned Blockchains called Votes-as-a-Proof (VaaP) with high transaction processing efficiency while ensuring high scalability. Every node in VaaP runs a simple consensus process based on voting in parallel. Faulty nodes will only deprive themselves of using consensus service. We present the comparison of VaaP and Sphinx, one of the state-of-the-art consensus protocols, analytically and experimentally (up to 500 nodes). The results indicate that VaaP outperforms Sphinx in throughput, latency and scalability.
J. G. L. A Jayasinghe, K. G. S. Shiranthaka, T. Kavith, M. H. D. V. Jayasinghe · 6 authors
Electronic health records (EHRs) have become the de facto standard for storing patient data in hospitals because of the data technology revolution. Many hospitals use server-based systems to keep track of patient medical records, however, this limits the scalability of those systems because they require a lot of storage space. Interoperability and security and privacy concerns, as well as cyber-attacks on the centralized storage, are among the issues they are dealing with. Lab report downloads can be compromised by a poor authentication mechanism that can be easily shared with a third party. Highlighted issues will be addressed by the proposed system, a Blockchain-based private patient information management system. Using a distributed, immutable, and secure ledger, the solution promises efficient system access and retrieval. Consensus can be achieved without consuming a big amount of energy or causing network congestion thanks to an enhanced consensus technique. Because of their tight zero-knowledge requirement, near-perfect data interchange across many platforms is possible thanks to Non-Fungible Tokens, which encourage openness and immutability in the data flow. In addition, the proposed system uses a mix of a hybrid access control system and public key cryptography to ensure high levels of data protection. Additionally, it is a fantastic accomplishment when Lab Report Download Portal and the report generator for medical lab reports can be connected to the main system, which can dynamically modify the report template format with multi-factor authentication enabled. Know your customer verification is also used to authenticate the user to the system. Decentralizing the medical industry’s data storage, sharing, and record-keeping is the general goal of this solution; this method eliminates the need for paper records.
Lin Chen, Qingchun Yu, Wei Liang, Jiahong Cai · 6 authors
With the increasing growth of electronic medical data, the difficulties of data sharing among medical institutions and the leakage of data privacy have become the focus of the public and medical workers. The blockchain has the characteristics of decentralization, traceability, and immutability, which can provide new ideas for fine-grained secure access to medical research. This article first introduces blockchain and blockchain-based privacy protection technology; then analyzes the advantages and disadvantages of electronic medical records, and introduces the current development status of electronic medical records based on blockchain technology; then from data encryption, access the three aspects of control and transaction anonymity introduce the medical data privacy protection method based on blockchain technology; finally, the full text is summarized and prospected.
Blockchains have seen growing traction with cryptocurrencies reaching a market cap of over 1 trillion dollars, major institution investors taking interests, and global impacts on governments, businesses, and individuals. Also growing significantly is the heterogeneity of the ecosystem where a variety of blockchains co-exist. Cross-chain bridge is a necessary building block in this multi-chain ecosystem. Existing solutions, however, either suffer from performance issues or rely on trust assumptions of committees that significantly lower the security. Recurring attacks against bridges have cost users more than 1.5 billion USD. In this paper, we introduce zkBridge, an efficient cross-chain bridge that guarantees strong security without external trust assumptions. With succinct proofs, zkBridge not only guarantees correctness, but also significantly reduces on-chain verification cost. We propose novel succinct proof protocols that are orders-of-magnitude faster than existing solutions for workload in zkBridge. With a modular design, zkBridge enables a broad spectrum of use cases and capabilities, including message passing, token transferring, and other computational logic operating on state changes from different chains. To demonstrate the practicality of zkBridge, we implemented a prototype bridge from Cosmos to Ethereum, a particularly challenging direction that involves large proof circuits that existing systems cannot efficiently handle. Our evaluation shows that zkBridge achieves practical performance: proof generation takes less than 20 seconds, while verifying proofs on-chain costs less than 230K gas. For completeness, we also implemented and evaluated the direction from Ethereum to other EVM-compatible chains (such as BSC) which involves smaller circuits and incurs much less overhead.
Blockchain has become one of the hottest research areas in recent years. The technology could potentially lead to a new generation of decentralized applications and decentralized autonomous organizations. Unfortunately, there is simply too much misinformation regarding blockchain. Most notably, blockchain has been used as a buzzword synonymous with data immutability and trust. In fact, this is far from the truth. In this article, we provide a concise description of exactly what blockchain technology is, including its design principle, building blocks, core innovations, and benefits. This is followed by an analysis of data immutability. We show that to create an insurmountable barrier against attacks on data immutability, decentralization and system scale are both necessary. Based on this analysis, we further dissect what benefits private and consortium blockchain could actually offer when decentralization is removed. We show that private and consortium blockchain cannot offer data immutability and trust as many works in the literature have claimed or implied. Instead, the centralized version of blockchain technology provides an elegant solution to achieving fault tolerance and atomic contract execution, which could make private and consortium blockchain useful for enterprises that would like to provide high availability to their customers and for their internal operations.