Follow blockchain research across journals, conferences, and preprint repositories.
9,005 results · page 301 of 376
Jingting Xue, Chunxiang Xu, Yuan Zhang, Lanhua Bai
No abstract is available for this record.
Patrick Li, Scott D. Nelson, Bradley Malin, You Chen
Background: Access to accurate and complete medication histories across healthcare institutions enables effective patient care. Histories across healthcare institutions currently rely on centralized systems for sharing medication data. However, there is a lack of efficient mechanisms to ensure that medication histories transferred from one institution to another are accurate, secure, and trustworthy. Methods: In this article, we introduce a decentralized medication management system (DMMS) that leverages the advantages of blockchain to manage medication histories. DMMS is realized as a decentralized network under the hyperledger fabric framework. Based on the network, we designed an architecture, within which each prescriber can create prescriptions for each patient and perform queries about historical prescriptions accordingly. Finally, we analyzed the advantages of DMMS over centralized systems in terms of accuracy, security, trustworthiness, and privacy. Results: We developed a proof of concept to showcase DMMS. In this system, a prescriber prescribes medications for a patient and then encrypts the prescriptions via the patient’s public keys. Patients can query their own prescriptions from different histories across healthcare institutions and then decrypt the prescriptions via their private keys. At the same time, a prescriber can query a patient’s prescription records across healthcare institutions after approval from the patient. Analytic results show that DMMS can improve security, trustworthiness, and privacy in medication history sharing and exchanging across healthcare institutions. In addition, we discuss the potential for DMMS in e-prescribing markets. Conclusions: This study shows that a distributed secure ledger can enable reliable, interoperable, and accurate medication history sharing. Keywords: Blockchain Ledger, Decentralized, Hyperledger Fabric Framework, Medication Histories Please see a related Letter to the Editor (https://doi.org/10.30953/bhty.v2.98), and its response (https://doi.org/10.30953/bhty.v2.108)
Bin Yu, Joseph K. Liu, Amin Sakzad, ‪Surya Nepal‬ · 7 authors
No abstract is available for this record.
Shaimaa Badr, Ibrahim Gomaa, Emad Abd-Elrahman
Recently, Blockchain is considered as one of the main powerful techniques in security and privacy domains. It is considered as the promised security concept for replacing the current third parities trusting solutions. This could be achieved by mixing some cryptography techniques, consensus algorithms alongside with some peer-to-peer communication protocols. In this paper, to meet the requirement of distributed structure in the eHealth Records (EHRs) system, we propose a novel protocol to achieve a perfect privacy preserving for the patient namely Pseudonym Based Encryption with Different Authorities (PBE-DA) by applying the concept of Blockchain on the healthcare communication entities in an e-health platform. Therefore, PBE-DA will be used to help the patient anonymously to access, check or update his sensitive data on EHRs system. Moreover, we analyzed not only the public blockchain tier between the different EHRs cloud provider but also another Blockchain tier between the patient sensors (IoT devices used to do some patient measurements) and the patient system as a gateway for the whole healthcare platform.
Marie Gotaas Buøen
No abstract is available for this record.
Massimo Bartoletti, Roberto Zunino
A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some funds remain frozen. The relevance of this issue is witnessed by a recent liquidity attack to the Ethereum Parity Wallet, which has frozen $${\sim }160M$$ USD within the contract, making this sum unredeemable by any user. We address the problem of verifying liquidity of Bitcoin contracts. Focussing on BitML, a contracts DSL with a computationally sound compiler to Bitcoin, we study various notions of liquidity. Our main result is that liquidity of BitML contracts is decidable, in all the proposed variants. To prove this, we first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of any given set of contracts, abstracting the context moves. With respect to the chosen contracts, this abstraction is sound and complete. Our decision procedure for liquidity is then based on model-checking the finite space of states of the abstraction.
Manuel Zander, Tom Waite, Dominik Harz
Scalability of distributed ledgers is a key adoption factor. As an alternative to blockchain-based protocols, directed acyclic graph (DAG) protocols are proposed with the intention to allow a higher volume of transactions to be processed. However, there is still limited understanding of the behaviour and security considerations of DAG-based systems. We present an asynchronous, continuous time, and multi-agent simulation framework for DAG-based cryptocurrencies. We model honest and semi-honest actors in the system to analyse the behaviour of one specific cryptocurrency, IOTA. Our simulations show that the agents that have low latency and a high connection degree have a higher probability of having their transactions accepted in the network with honest and semi-honest strategies. Last, the simulator is built with extensibility in mind. We are in the process of implementing SPECTRE as well as including malicious agents.
Wei Yin, Qiaoyan Wen, Wenmin Li, Hua Zhang · 5 authors
Blockchain is a new distributed and decentralized technology, and gradually attracts worldwide attention, but it is vulnerable to quantum attacks that would solve elliptic curve digital logarithm problem, which is mainly used for transaction authentication in blockchain. The key needed for authentication comes from the wallet. To ensure that the size of the wallet is fixed and easy to manage, deterministic wallets are required to be used. But if existing anti-quantum signature schemes, such as lattice-based signature are used directly in blockchain to solve the problem, it would have made the wallet bloat. In this paper, we present a novel anti-quantum transaction authentication scheme in the blockchain. In order to construct lightweight nondeterministic wallets, the key point is that public and private keys are generated from a set of master public and private key(Seed Key). We leverage on Bonsai Trees technology and propose a new authentication method which can extend a lattice space to multiple lattice spaces accompanied by the corresponding key. Every signature of a transaction uses a lattice space so as to ensure the randomness and the security of the master private key. And we give the complete security proof and analysis. This paper provides the theoretical support for the application of blockchain in the post quantum age.
Lijing Zhou, Licheng Wang, Yiru Sun, Pin Lv
Currently, Internet of Things (IoT) and blockchain technologies are experiencing exponential growth in academia and industry. Generally, IoT is a centralized system whose security and performance mainly rely on centralized servers. Therefore, users have to trust the centralized servers; in addition, it is difficult to coordinate external computing resources to improve the performance of IoT. Fortunately, the blockchain may provide this decentralization, high credibility and high security. Consequently, blockchain-based IoT may become a reasonable choice for the design of a decentralized IoT system. In this paper, we propose a novel blockchain-based threshold IoT service system: BeeKeeper. In the BeeKeeper system, servers can process a user's data by performing homomorphic computations on the data without learning anything from them. Furthermore, any node can become a leader's server if the node and the leader desire so. In this way, BeeKeeper's performance can continually increase by attracting external computing resources to join in it. Moreover, malicious nodes can be scrutinized. In addition, BeeKeeper is fault tolerant since a user's BeeKeeper protocol may work smoothly as long as a threshold number of its servers are active and honest. Finally, we deploy BeeKeeper on the Ethereum blockchain and give the corresponding performance evaluation. In our experiments, servers can generate their response with about 107 ms. Moreover, the performance of BeeKeeper mainly depends on the blockchain platform. For instance, the response time is about 22.5 s since the block interval of Ethereum blockchain is about 15 s. In fact, if we use some other blockchain with short block interval, the response time may be obviously short.
Baocheng Wang, Jiawei Sun, Yunhua He, Dandan Pang · 5 authors
Based on the blockchain, homomorphic ElGamal encryption and ring signature, an electronic voting scheme based on blockchain is proposed for large-scale voting, which has the properties of decentralization, self-management, non-interactive and free-receipt, furthermore the one-time ring signature ensures the anonymity of the vote trading in the blockchain. The public verifiable billboards guarantee the voting fair, and the miner nodes provides ciphertext ballot counting service makes large-scale voting feasible. Finally, we analysis the security of the blockchain voting system and present the performance in large-scale nodes.
Krishnendu Chatterjee, Amir Kafshdar Goharshady, Yaron Velner
Smart contracts are computer programs that are executed by a network of mutually distrusting agents, without the need of an external trusted authority. Smart contracts handle and transfer assets of considerable value (in the form of crypto-currency like Bitcoin). Hence, it is crucial that their implementation is bug-free. We identify the utility (or expected payoff) of interacting with such smart contracts as the basic and canonical quantitative property for such contracts. We present a framework for such quantitative analysis of smart contracts. Such a formal framework poses new and novel research challenges in programming languages, as it requires modeling of game-theoretic aspects to analyze incentives for deviation from honest behavior and modeling utilities which are not specified as standard temporal properties such as safety and termination. While game-theoretic incentives have been analyzed in the security community, their analysis has been restricted to the very special case of stateless games. However, to analyze smart contracts, stateful analysis is required as it must account for the different program states of the protocol. Our main contributions are as follows: we present (i)~a simplified programming language for smart contracts; (ii)~an automatic translation of the programs to state-based games; (iii)~an abstraction-refinement approach to solve such games; and (iv)~experimental results on real-world-inspired smart contracts.
Qi Zhang, Petr Novotny, Salman Baset, Donna N. Dillenberger · 6 authors
The rise of crypto-currencies has spawned great interest in their underlying technology, namely, Blockchain. The central component in a Blockchain is a shared distributed ledger. A ledger comprises series of blocks, which in turns contains a series of transactions. An identical copy of the ledger is stored on all nodes in a blockchain network. Maintaining ledger integrity and security is one of the crucial design aspects of any blockchain platform. Thus, there are typically built-in validation mechanisms leveraging cryptography to ensure the validity of incoming blocks before committing them into the ledger. However, a blockchain node may run over an extended period of time, during which the blocks on the disk can may become corrupted due to software or hardware failures, or due to malicious activity. This paper proposes LedgerGuard, a tool to maintain ledger integrity by detecting corrupted blocks and recovering these blocks by synchronizing with rest of the network. The experimental implementation of LedgerGuard is based on Hyperledger Fabric, which is a popular open source permissioned blockchain platform.
Ivan Damgård, Ji Luo, Sabine Oechsner, Peter Schöll · 5 authors
No abstract is available for this record.
Spencer J. Hosack
Recent attention to Bitcoin and other cryptocurrencies has opened investors and the public to the realm of digital currency. Greater exposure around the world has led to a frenzy of entry into the market and a test into the long-term feasibility of Bitcoin being able to remain a functioning peer-to-peer (P2P), decentralized currency. Its main structure is supported by the Proof-of-Work (PoW) protocol in which users can elect to participate in determining transaction approval and ensuring an honest blockchain. This system relies on elected users to expend computational power and energy to solve puzzles to prove the accuracy of the network’s transactions and create new blocks.\nEach cryptocurrency uses their own method to ensure blockchain accuracy, and this paper will focus on how a Proof-of-Stake (PoS) protocol is a superior algorithm to PoW by assigning mining ability equal to one’s stake within a coin, rather than her energy consumption, among other factors. We will discuss Bitcoin’s PoW as a baseline for our eventual analysis of PoS in terms of advantages and performance metrics. The main factors that can be compared between the two protocols is how each system can prevent itself against a variety of attacks from adversarial users within the network, as well as long-term sustainability.\nFinally, we will use the Cardano (ADA) cryptocurrency by IOHK as a case study for understanding how their Ouroboros Praos PoS protocol works. Our goal is to show how long-term adoption of PoS framework is more realistic from an energy perspective than PoW.
Craig Calcaterra, Wulf A. Kaal
No abstract is available for this record.
Massimo Bartoletti, Tiziana Cimoli, Roberto Zunino
Besides simple transfers of currency, Bitcoin also enables various forms of smart contracts, i.e. protocols where users interact within pre-agreed rules, which determine (possibly depending on the actual interaction) how currency is eventually distributed. This paper provides a gentle introduction to Bitcoin smart contracts, which we specify by abstracting from the underlying Bitcoin machinery. To this purpose we exploit BitML, a recent DSL for smart contracts executable on Bitcoin.
Alexander Chepurnoy, Charalampos Papamanthou, Yupeng Zhang
No abstract is available for this record.
Shuangyu He, Qianhong Wu, Xizhao Luo, Zhi Liang · 8 authors
Effective cryptocurrency key management has become an urgent requirement for modern cryptocurrency. Although a large body of cryptocurrency wallet-management schemes has been proposed, they are mostly constructed for specific application scenarios and often suffer from weak security. In this paper, we propose a more effective, usable, and secure cryptocurrency wallet-management system based on semi-trusted social networks, therein allowing users to collaborate with involved parties to achieve some powerful functions and recovery under certain circumstances. Furthermore, we employ an identity-based hierarchical key-insulated encryption scheme to achieve time-sharing authorization and present a semi-trusted portable social-network-based wallet-management scheme that provides the features of security-enhanced storage, portable login on different devices, no-password authentication, flexible key delegation, and so on. The performance analysis shows that our proposed schemes require minimal additional overhead and have low time delays, making them sufficiently efficient for real-world deployment.
Trishita Tiwari, David Starobinski, Ari Trachtenberg
No abstract is available for this record.
Qun Lin, Hongyang Yan, Zhengan Huang, Wenbin Chen · 6 authors
Identity-based cryptosystems mean that public keys can be directly derived from user identifiers, such as telephone numbers, email addresses, and social insurance number, and so on. So they can simplify key management procedures of certificate-based public key infrastructures and can be used to realize authentication in blockchain. Linearly homomorphic signature schemes allow to perform linear computations on authenticated data. And the correctness of the computation can be publicly verified. Although a series of homomorphic signature schemes have been designed recently, there are few homomorphic signature schemes designed in identity-based cryptography. In this paper, we construct a new ID-based linear homomorphic signature scheme, which avoids the shortcomings of the use of public-key certificates. The scheme is proved secure against existential forgery on adaptively chosen message and ID attack under the random oracle model. The ID-based linearly homomorphic signature schemes can be applied in e-business and cloud computing. Finally, we show how to apply it to realize authentication in blockchain.
Nils Fleischhacker, Vipul Goyal, Abhishek Jain
We study the round complexity of zero-knowledge (ZK) proof systems. While five round ZK proofs for \({\mathsf {NP}}\) are known from standard assumptions [Goldreich-Kahan, J. Cryptology’96], Katz [TCC’08] proved that four rounds are insufficient for this task w.r.t. black-box simulation. In this work, we study the feasibility of ZK proofs using non-black-box simulation. Our main result is that three round private-coin ZK proofs for \({\mathsf {NP}}\) do not exist (even w.r.t. non-black-box simulation), under certain assumptions on program obfuscation. Our approach builds upon the recent work of Kalai et al. [Crypto’17] who ruled out constant round public-coin ZK proofs under the same assumptions as ours.
David Derler, Sebastian Ramacher, Daniel Slamanig
No abstract is available for this record.
Jonathan Bootle, Andrea Cerulli, Jens Groth, S. Jakobsen · 5 authors
No abstract is available for this record.
Rafaël del Pino, Vadim Lyubashevsky, Gregor Seiler
We present a group signature scheme, based on the hardness of lattice problems, whose outputs are more than an order of magnitude smaller than the currently most efficient schemes in the literature. Since lattice-based schemes are also usually non-trivial to efficiently implement, we additionally provide the first experimental implementation of lattice-based group signatures demonstrating that our construction is indeed practical -- all operations take less than half a second on a standard laptop. A key component of our construction is a new zero-knowledge proof system for proving that a committed value belongs to a particular set of small size. The sets for which our proofs are applicable are exactly those that contain elements that remain stable under Galois automorphisms of the underlying cyclotomic number field of our lattice-based protocol. We believe that these proofs will find applications in other settings as well. The motivation of the new zero-knowledge proof in our construction is to allow the efficient use of the selectively-secure signature scheme (i.e. a signature scheme in which the adversary declares the forgery message before seeing the public key) of Agrawal et al. (Eurocrypt 2010) in constructions of lattice-based group signatures and other privacy protocols. For selectively-secure schemes to be meaningfully converted to standard signature schemes, it is crucial that the size of the message space is not too large. Using our zero-knowledge proofs, we can strategically pick small sets for which we can provide efficient zero-knowledge proofs of membership.