As the basis of cloud computing, distributed storage technology mainly studies how data centers store, organize and manage data. Blockchain has become the most secure solution for cloud storage due to its decentralization and immutability. Consensus mechanism is one of the core technologies of blockchain, which affects the transaction processing capability, security and scalability of blockchain. The current mainstream consensus algorithms such as Proof of Work, Proof of Stake, and Delegated Proof of Stake all have the problem of wasting resources. And with the explosive growth of data, cloud storage nodes store a large amount of redundant data, which inevitably increases storage overhead and computing cost. To this end, we propose to use the Proof of Retrievability with deduplication algorithm as the consensus mechanism of the blockchain system and design a blockchain consensus protocol suitable for distributed storage. First, the data integrity verification protocol in the scheme guarantees that storage nodes correctly store the data they promise to store. Second, the deduplication algorithm in the protocol can optimize data auditing, greatly reduce the need for data storage space, and improve the scalability of data transmission. In addition, the scheme uses ring signatures in the audit process to ensure user anonymity and data unlinkability, while providing highly reliable data storage, and ensuring data storage security through blockchain. Finally, we demonstrate the security of the proposed scheme and evaluate its performance. The evaluation results show that our scheme is efficient and scalable.
Decentralized applications (DApps) gained traction in the context of the blockchain technology. Ethereum is currently the public blockchain that backs the largest amount of the existing DApps. Onboarding new users to Ethereum DApps is a notoriously hard issue to solve. This is mainly caused by lack of cryptocurrency ownership, needed for transaction fees. Several meta-transaction patterns emerged for decoupling users from paying these fees. However, such solutions are mostly offered via off-chain, often paid relayer services and do not fully address the security issues present in the meta-transaction path. In this paper, we introduce a new meta-transaction architecture that makes use of the Intel Software Guard Extensions (SGX). Unlike other solutions, our approach would offer the possibility to deploy a fee-free Ethereum DApp on a web server that can directly relay meta-transactions to the Ethereum network while having essential security guarantees integrated by design.
Haya R. Hasan, Khaled Salah, Ammar Battah, Mohammad Madine · 7 authors
Non-Fungible Tokens (NFTs) have recently received immense popularity in the digital art industry. An NFT represents ownership of a unique item that is stored on the blockchain and cannot be changed, replaced, and copied. The current NFT ecosystem falls short in trust features and is prone to illegitimate users, threats, and vulnerabilities. In this paper, we propose a blockchain-based solution for the NFT ecosystem that incorporates registration of the participating actors, involves a decentralized reputation system, provides incentives to its users through rewards, and penalizes misconduct. Our system design is built to ensure trust and credibility in the NFT ecosystem. The proposed solution leverages blockchain’s intrinsic security features such as transparency, tamper-proof logs, data integrity, accountability, and non-repudiation. We use the decentralized storage of the InterPlanetary File System (IPFS) to store the NFTs’ metadata, whereas their hash is stored on the chain. We present algorithms along with their implementation, testing, and validation details. We demonstrate how our solution, as well as smart contract code, is secure enough against common security threats and attacks. We make our smart contract code publicly available on the GitHub repository.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Since public blockchains are permissionless, it is subject to passive adversarial attack. In 5irechain we have addressed the security problem related to this passive adversarial activity by applying 5ireHE, a homomorphic encryption technique that encrypts the transactional details using the receiver’s public key. Since the transaction is encrypted by the receiver’s public key, it is harder for other validators to validate the transaction in 5ire. In this paper, we introduce ZKP for validating the transaction in a sense that validator can check if the sender’s previous balance and the remaining balance are in harmony with the amount of the transaction despite the difference in public keys that are used for the encryption of transaction and the encryption of account balance.
Omar Sefraoui, Afaf Bouzidi, Kamal Ghoumid, El Miloud Ar-Reyouchi
Nowadays, connected devices are growing exponen-tially; their produced data traffic has increased unprecedent-edly. Information systems security and cybersecurity are critical because data typically contain sensitive personal information, requiring high data protection. An authentication system manages and controls access to this data allowing the system to ensure the legitimacy of the access request. Most of the current identification and authentication systems are based on a centralized architec-ture. However, some concepts as Cloud computing and Blockchain use respectively distributed and decentralized architectures. Users without a central server will own platforms and applications of the next generation of Internet and Web3. This paper proposes AuSDiDe, a new authentication system for the distributed and decentralized structure. This solution aims to divide and share keys toward different and distributed nodes. The main objective of AuSDiDe is to securely store and manage passwords, private keys, and authentication based on the Shamir secret sharing algo-rithm. This new proposal significantly reinforces data protection in information security.
With the rapid development of blockchain technology in recent years, all kinds of blockchain-based applications have emerged. Among them, the decentralized finance (DeFi) is one of the most successful applications, which is regarded as the future of finance. The great success of DeFi relies on the real-world data which is not directly available on the blockchain. However, due to the deterministic nature of blockchain, the blockchain cannot directly obtain indeterministic data from the outside world (off-chain). Thus, oracles have appeared as a viable solution to feed off-chain data to blockchain applications. In this paper, we carry out a comprehensive study on oracles, especially on DeFi oracles. We first briefly introduce the application scenarios of DeFi oracles, and then we talk about the past of DeFi oracles by categorizing them into several types based on their design features. After that, we introduce five popular DeFi oracles currently in use (such as Chainlink and Band Protocol), with the focus on their system architecture, data validation process, and their incentive mechanisms. Then, we compare these present DeFi oracles from their data trustworthiness, data source trustworthiness and their overall trust models. Finally, we propose a set of metrics for designing trustworthiness DeFi oracles, and propose a potential trust architecture and a few promising techniques for building future trustworthiness oracles.
Non-Fungible Tokens (NFTs) have lately piqued the interest of investors, with some NFTs achieving selling levels previously inconceivable for a non-fungible virtual asset. This raises intriguing questions about "value" and "scarcity" in relation to blockchain technology, viewed through the lens of a digital asset's non-fungibility, This study seeks to attract attention to these issues inasmuch as they may create a future alternative environment for blockchain development and trading.
We propose a privacy-preserving scheme to outsource zero-knowledge proof generation to a party that we call a worker. Our scheme can be applied to zk-SNARKs with a trusted setup, zero-knowledge proofs deployed in many applications. Compared to known privacy-preserving outsourcing schemes, our scheme is more practical in the sense that the computational and memory load on the worker is almost the same as that on the prover in cases where the provers generate proofs on their own.
Immutability has been widely accepted as a fundamental property protecting the security of blockchain technology. However, this property impedes the development of blockchain because of the abuse of blockchain storage and legal obligations. To mitigate this issue, a novel construction of blockchain, calledredactable blockchain, was introduced. It enables a central authority to issue the rewriting privilege to a particular party who can rewrite a registered object, e.g., a block or a transaction, in a controlled way. Unfortunately, the central authority must be fully trusted and is an obvious target suffering from various attacks. In this paper, we introduce a redactable blockchain controlled at a fine-grained level in a decentralized setting. In our solution, the rewriting privilege is issued by multiple authorities for reducing the vulnerability of the centralized setting. To formalize our solution, we introduce a novel cryptographic notion, calleddecentralized policy-based chameleon hash(DPCH), with the formal definition and security model. By applying several simple cryptographic tools, such as chameleon hash, digital signature, and multi-authority attribute-based encryption, we present the generic construction of DPCH along with rigorous security proofs. By applying RSA-based chameleon hash and BLS short signature, we give a practical instantiation of DPCH with performance evaluation. The comprehensive evaluation shows that our solution has superior performance than the state-of-the-art solution.
Trust management systems often use registries to authenticate data, or form trust decisions. Examples are revocation registries and trust status lists. By introducing distributed ledgers (DLs), it is also possible to create decentralized registries. A verifier then queries a node of the respective ledger, e.g., to retrieve trust status information during the verification of a credential. While this ensures trustworthy information, the process requires the verifier to be online and the ledger node available. Additionally, the connection from the verifier to the registry poses a privacy issue, as it leaks information about the user's behavior. In this paper, we resolve these issues by extending existing ledger APIs to support results that are trustworthy even in an offline setting. We do this by introducing attestations of the ledger's state, issued by ledger nodes, aggregatable into a collective attestation by all nodes. This attestation enables a user to prove the provenance of DL-based data to an offline verifier. Our approach is generic. So once deployed it serves as a basis for any use case with an offline verifier. We also provide an implementation for the Ethereum stack and evaluate it, demonstrating the practicability of our approach.
Tao Feng, Pu Yang, Chunyan Liu, Junli Fang · 5 authors
The data generated in the Industrial Internet of Things (IIoT) has important research value. In the process of data sharing, data privacy, security, and data availability are important issues that cannot be ignored. This paper proposes a blockchain privacy protection scheme based on zero‐knowledge proof to realize the secure sharing of data among data owners, cloud service providers, and semitrusted cloud servers. First, the method of combining zero‐knowledge proof and smart contract is used to verify the availability of data between the data owner and the cloud service provider under the premise of protecting data privacy. Second, proxy reencryption technology is used to realize the secure sharing of data among authorized cloud service providers. In addition, data sharing transaction information between multiple parties and data hashes with digital signatures are stored on the blockchain to achieve public and verifiable data sharing information and data validity. Finally, the theoretical analysis of the scheme shows that the scheme meets the confidentiality requirements of security, integrity, and validity.
Standardized Ethereum tokens, e.g., ERC-20 tokens, have become the norm in fundraising (through ICOs) and kicking off blockchain-based DeFi applications. However, they require the user's wallet to hold both tokens and ether to pay the gas fee for making a transaction. This makes for a cumbersome user experience, and complicates, from the user perspective, the process of transitioning to a different smart-contract enabled blockchain, or to a newly launched blockchain. We formalize, instantiate, and analyze in a composable manner a system that we call Etherless Ethereum Tokens (in short, EETs), which allows the token users to transact in a closed-economy manner, i.e., having only tokens on their wallet and paying any transaction fees in tokens rather than Ether/Gas. In the process, we devise a methodology for capturing Ethereum token-contracts in the Universal Composability (UC) framework, which can be of independent interest.
Marcela Tuler de Oliveira, Lúcio Henrik A. Reis, Yiannis Verginadis, Diogo M. F. Mattos · 5 authors
Cross-organisation data sharing is challenging because all the involved organisations must agree on ’how’ and ’why’ the data is processed. Due to a lack of transparency, the organisations need to trust that others comply with the agreements and regulations. We propose to exploit blockchain and smart contracts technologies to define an Attribute-Based Access Control System for cross-organisation medical records sharing, coined SmartAccess. SmartAccess offers joint agreement over access policies and dynamic access control besides blockchain transparency and auditability. We leverage the Attribute-Based Access Control model to implement smart contracts.We deploy and test them on a private and permissioned blockchain, transforming the access control process into a distributed smart contract execution. This paper proposes the SmartAccess system and its application in two healthcare use cases. We introduce the threat model and perform a security analysis of the system. To demonstrate the feasibility of our proposal, we implement a proof-of-concept of the smart contracts, written in Solidity language, with a size-efficient policy representation, and analyse the complexity and scalability of the contracts’ functions. Furthermore, we present performance results, measuring the latency and throughput of the transactions to execute the access control functions with different blockchain network consensus setups. We also compare the performance of the SmartAccess system against two open-source Solidity implementations of smart contract-based access control, Role-based Access Control and Access Control List. Finally, we discuss the strengths and drawbacks of our proposal. SmartAccess requires the overhead of a decentralised system, but the trade-off is transparency, regulation compliance and auditability for complex cross-organisation data sharing.
Data sharing is a crucial step in the research community to make the most of the prior effort. Platforms for sharing data currently in use rely on trustworthy third parties (TTP). Such systems lack immutability, security, transparency, and trust because of TTP’s involvement. In order to address these problems, the proposed system approaches an Interplanetary File System (IPFS)-based blockchain-based secure data sharing platform. The user uploads a data file to the IPFS server, which is subsequently split up into several secret shares. By carrying out the access responsibilities that the user has specified in the smart contract, the suggested scheme accomplishes security and access control. This scenario combines encryption, Ethereum blockchain technology, decentralized storage, and incentive systems. Solidity smart contracts are created and deployed on a local Ethereum test network in order to carry out the suggested scenario. Transparency, Security, Access control, Owner authenticity, and Data quality are all achieved by the suggested plan.
The Internet of things (IoT) is the key enabler of the smart systems used in many areas, from agriculture to aviation, industrial automation to autonomous vehicles. Most IoT deployments employ cost-efficient lightweight devices with limited resources (e.g., bandwidth, energy, storage). Although an IoT network must be built in its simplest form, engineers include more sophisticated devices like gateways and servers to provide web-based services and benefit from cloud systems. So, although the nodes can be widely distributed geographically or topologically, the system becomes centralized, which causes bottlenecks and single-points-of-failure. Furthermore, providing data integrity, nonrepudiation, and event management becomes tricky. In most IoT scenarios, data usually flow from sensors to storage and processing units, whereas event-driven commands and triggers flow from these units to actuators, if any. Therefore, an attacker who gained access to parts of the centralized systems may leak, alter, or remove critical data and may exploit event handling features. This is where blockchain technology can be extremely useful. Using a decentralized ledger as the data storage unit provides integrity, immutability, and nonrepudiation for any IoT deployment. And a customized smart contract lets the IoT deployment benefit from decentralized and immutable (i.e. nonmanipulatable) event management features, too. Further, decentralization provides resilience against availability attacks to a large extent. With this motivation, we introduced a novel IoT architecture that incorporates an Ethereum-based private (Quorum) blockchain running a unique ad-hoc smart contract and a message queue telemetry transport (MQTT) based communication scheme between sensor and actuator nodes. The scheme, the ledger, and the smart contract have also been implemented with several nodes, a broker, and a server all on a PC using Docker containers, where the server was running a forest fire risk detection algorithm as the use case scenario. The proof-of-concept successfully validates the abovesaid functionality, scalability, and efficiency for the given IoT scenario (and some others). Moreover, performance tests showed that an instance of the system with 1000 nodes could stably process and record incoming (sensor) data up to 12.5 transactions per second (TPS) and distribute commands up to 4 TPS, whereas higher TPS is achievable depending on the network conditions and tolerance to losses. The scheme was shown to have polynomial message and time complexity.
Rodrigo Dutra Garcia, Gowri Ramachandran, Raja Jurdak, Jó Ueyama
Real-world applications in healthcare and supply chain domains produce, exchange, and share data in a multi-stakeholder environment. Data owners want to control their data and privacy in such settings. On the other hand, data consumers demand methods to understand when, how, and who produced the data. These requirements necessitate data governance frameworks that guarantee data provenance, privacy protection, and consent management. We introduce a decentralized data governance framework based on blockchain technology and proxy re-encryption to let data owners control and track their data through privacy-enhancing and consent management mechanisms. Besides, our framework allows the data consumers to understand data lineage through a blockchain-based provenance mechanism. We have used Digital e-prescription as the use case since it has multiple stakeholders and sensitive data while enabling the medical fraternity to manage patients' prescription data, involving patients as data owners, doctors and pharmacists as data consumers. Our proof-of-concept implementation and evaluation results based on CosmWasm, Ethereum, and pyUmbral PRE show that the proposed decentralized system guarantees transparency, privacy, and trust with minimal overhead.
The existing domain name system relies heavily on the root domain name server and has unilateral management problems, which is not conducive to the open and equal development of the Internet environment. Blockchain technology provides new technical means to solve the centralization problem of the root resolution system but induces high consumption and slow query issues. In this paper, we studied optimizing the blockchain smart contract virtual machine, specifically EVM (Ethereum Virtual Machine), for realizing a domain name system through a smart contract. We abstracted the key data structure of domain name management and added core attributes to the account structure to accelerate domain name management through transactions. Furthermore, we modified the EVM structure and added EVM opcodes that can directly call the underlying logic related to upper-level domain name management to simplify the transaction processing flow. The evaluations show that the system has achieved a two orders of magnitude improvement in the performance of the domain name resolution system based on blockchain.