Follow blockchain research across journals, conferences, and preprint repositories.
9,005 results · page 303 of 376
Nicola Atzei, Massimo Bartoletti, Stefano Lande, Roberto Zunino
No abstract is available for this record.
Gregory Maxwell, Andrew Poelstra, Yannick Seurin, Pieter Wuille
We describe a new Schnorr-based multi-signature scheme (i.e., a protocol which allows a group of signers to produce a short, joint signature on a common message) called $$\mathsf {MuSig}$$ , provably secure under the Discrete Logarithm assumption and in the plain public-key model (meaning that signers are only required to have a public key, but do not have to prove knowledge of the private key corresponding to their public key to some certification authority or to other signers before engaging the protocol). $$\mathsf {MuSig}$$ improves over the state-of-art scheme of Bellare and Neven (ACM Conference on Computer and Communications Security-CCS 2006) and its variants by Bagherzandi et al. (ACM Conference on Computer and Communications Security-CCS 2008) and Ma et al. (Des Codes Cryptogr 54(2):121–133, 2010) in two respects: (i) it is simple and efficient, having the same key and signature size as standard Schnorr signatures; (ii) it allows key aggregation, which informally means that the joint signature can be verified exactly as a standard Schnorr signature with respect to a single “aggregated” public key which can be computed from the individual public keys of the signers. To the best of our knowledge, this is the first multi-signature scheme provably secure under the Discrete Logarithm assumption in the plain public-key model which allows key aggregation. As an application, we explain how our new multi-signature scheme could improve both performance and user privacy in Bitcoin.
Dan Boneh, Benedikt Bünz, Ben Fisch
We present batching techniques for cryptographic accumulators and vector commitments in groups of unknown order. Our techniques are tailored for distributed settings where no trusted accumulator manager exists and updates to the accumulator are processed in batches. We develop techniques for non-interactively aggregating membership proofs that can be verified with a constant number of group operations. We also provide a constant sized batch non-membership proof for a large number of elements. These proofs can be used to build the first positional vector commitment (VC) with constant sized openings and constant sized public parameters. As a core building block for our batching techniques we develop several succinct proof systems in groups of unknown order. These extend a recent construction of a succinct proof of correct exponentiation, and include a succinct proof of knowledge of an integer discrete logarithm between two group elements. We circumvent an impossibility result for Sigma-protocols in these groups by using a short trapdoor-free CRS. We use these new accumulator and vector commitment constructions to design a stateless blockchain, where nodes only need a constant amount of storage in order to participate in consensus. Further, we show how to use these techniques to reduce the size of IOP instantiations, such as STARKs. The full version of the paper is available online [BBF18b].
Rafael Pass, Elaine Shi
No abstract is available for this record.
Dan Boneh, Manu Drijvers, Gregory Neven
No abstract is available for this record.
Rui Guo, Huixian Shi, Qinglan Zhao, Dong Zheng
Electronic Health Records (EHRs) are entirely controlled by hospitals instead of patients, which complicates seeking medical advices from different hospitals. Patients face a critical need to focus on the details of their own healthcare and restore management of their own medical data. The rapid development of blockchain technology promotes population healthcare, including medical records as well as patient-related data. This technology provides patients with comprehensive, immutable records, and access to EHRs free from service providers and treatment websites. In this paper, to guarantee the validity of EHRs encapsulated in blockchain, we present an attribute-based signature scheme with multiple authorities, in which a patient endorses a message according to the attribute while disclosing no information other than the evidence that he has attested to it. Furthermore, there are multiple authorities without a trusted single or central one to generate and distribute public/private keys of the patient, which avoids the escrow problem and conforms to the mode of distributed data storage in the blockchain. By sharing the secret pseudorandom function seeds among authorities, this protocol resists collusion attack out of N from N -1 corrupted authorities. Under the assumption of the computational bilinear Diffie-Hellman, we also formally demonstrate that, in terms of the unforgeability and perfect privacy of the attribute-signer, this attribute-based signature scheme is secure in the random oracle model. The comparison shows the efficiency and properties between the proposed method and methods proposed in other studies.
Bernardo David, Peter Gaži, Aggelos Kiayias, Alexander Russell
No abstract is available for this record.
Shangping Wang, Yinglong Zhang, Yaling Zhang
In traditional cloud storage systems, attribute-based encryption (ABE) is regarded as an important technology for solving the problem of data privacy and fine-grained access control. However, in all ABE schemes, the private key generator has the ability to decrypt all data stored in the cloud server, which may bring serious problems such as key abuse and privacy data leakage. Meanwhile, the traditional cloud storage model runs in a centralized storage manner, so single point of failure may leads to the collapse of system. With the development of blockchain technology, decentralized storage mode has entered the public view. The decentralized storage approach can solve the problem of single point of failure in traditional cloud storage systems and enjoy a number of advantages over centralized storage, such as low price and high throughput. In this paper, we study the data storage and sharing scheme for decentralized storage systems and propose a framework that combines the decentralized storage system interplanetary file system, the Ethereum blockchain, and ABE technology. In this framework, the data owner has the ability to distribute secret key for data users and encrypt shared data by specifying access policy, and the scheme achieves fine-grained access control over data. At the same time, based on smart contract on the Ethereum blockchain, the keyword search function on the cipher text of the decentralized storage systems is implemented, which solves the problem that the cloud server may not return all of the results searched or return wrong results in the traditional cloud storage systems. Finally, we simulated the scheme in the Linux system and the Ethereum official test network Rinkeby, and the experimental results show that our scheme is feasible.
Archana Prashanth Joshi, Meng Han, Yan Wang
Blockchain is gaining traction and can be termed as one of the furthermost prevalent topics nowadays. Although critics question about its scalability, security, and sustainability, it has already transformed many individuals' lifestyle in some areas due to its inordinate influence on industries and businesses. Granting that the features of blockchain technology guarantee more reliable and expedient services, it is important to consider the security and privacy issues and challenges behind the innovative technology. The spectrum of blockchain applications range from financial, healthcare, automobile, risk management, Internet of things (IoT) to public and social services. Several studies focus on utilizing the blockchain data structure in various applications. However, a comprehensive survey on technical and applications perspective has not yet been accomplished. In this paper, we try to conduct a comprehensive survey on the blockchain technology by discussing its structure to different consensus algorithms as well as the challenges and opportunities from the prospective of security and privacy of data in blockchains. Furthermore, we delve into future trends the blockchain technology can adapt in the years to come.Index Terms- Blockchains, Future Trends of Blockchains, Security, Privacy
Christian Esposito, Alfredo De Santis, Genny Tortora, Henry Chang · 5 authors
One particular trend observed in healthcare is the progressive shift of data and services to the cloud, partly due to convenience (e.g. availability of complete patient medical history in real-time) and savings (e.g. economics of healthcare data management). There are, however, limitations to using conventional cryptographic primitives and access control models to address security and privacy concerns in an increasingly cloud-based environment. In this paper, we study the potential to use the Blockchain technology to protect healthcare data hosted within the cloud. We also describe the practical challenges of such a proposition and further research that is required.
George Pîrlea, Ilya Sergey
We present the first formalisation of a blockchain-based distributed consensus protocol with a proof of its consistency mechanised in an interactive proof assistant.
Sidney Amani, Myriam Bégel, Maksym Bortin, Mark Staples
Blockchain technology has increasing attention in research and across many industries. The Ethereum blockchain offers smart contracts, which are small programs defined, executed, and recorded as transactions in the blockchain transaction history. These smart contracts run on the Ethereum Virtual Machine (EVM) and can be used to encode agreements, transfer assets, and enforce integrity conditions in relationships between parties. Smart contracts can carry financial value, and are increasingly used for safety-, security-, or mission-critical purposes. Errors in smart contracts have led and will lead to loss or harm. Formal verification can provide the highest level of confidence about the correct behaviour of smart contracts. In this paper we extend an existing EVM formalisation in Isabelle/HOL by a sound program logic at the level of bytecode. We structure bytecode sequences into blocks of straight-line code and create a program logic to reason about these. This abstraction is a step towards control of the cost and complexity of formal verification of EVM smart contracts.
Kun-Tai Chan, Raylin Tso, Chien‐Ming Chen, Mu‐En Wu
No abstract is available for this record.
Jen-Ho Hsiao, Raylin Tso, Chien‐Ming Chen, Mu‐En Wu
No abstract is available for this record.
Anunay Kulshrestha, Akshay Rampuria, Matthew Denton, Ashwin Sreenivas
We introduce a robust framework that allows for cryptographically secure multiparty computations, such as distributed private value auctions. The security is guaranteed by two-sided authentication of all network connections, homomorphically encrypted bids, and the publication of zero-knowledge proofs of every computation. This also allows a non-participant verifier to verify the result of any such computation using only the information broadcasted on the network by each individual bidder. Building on previous work on such systems, we design and implement an extensible framework that puts the described ideas to practice. Apart from the actual implementation of the framework, our biggest contribution is the level of protection we are able to guarantee from attacks described in previous work. In order to provide guidance to users of the library, we analyze the use of zero knowledge proofs in ensuring the correct behavior of each node in a computation. We also describe the usage of the library to perform a private-value distributed auction, as well as the other challenges in implementing the protocol, such as auction registration and certificate distribution. Finally, we provide performance statistics on our implementation of the auction.
Changsong Yang, Xiaofeng Chen, Yang Xiang
No abstract is available for this record.
Volker Skwarek
Purpose This paper aims to describe a method for Internet-of-Things-devices to achieve industrial grade reliability for information transfer from wireless sensor systems to production systems using blockchain technologies. Design/methodology/approach An increased security and reliability of submitted data within the sensor network could be achieved on an application level. Therefore, a lightweight, high-level communication protocol based on blockchain principles was designed. Findings Blockchain mechanisms can secure the wireless communication of Internet-of-Things-devices in a lightweight and scalable manner. Originality/value The innovation of this research is the successful application of general blockchain mechanisms to increase security of a wireless sensor system without binding to a dedicated blockchain technology.
Daniel Conte de Leon, Antonius Q. Stalick, Ananth A. Jillepalli, Michael Haney · 5 authors
Purpose - The purpose of this article is to clarify current and widespread misconceptions about the properties of blockchain technologies and to describe challenges and avenues for correct and trustworthy design and implementation of distributed ledger system (DLS) or Technology (DLT). Design/methodology/approach - The authors contrast the properties of a blockchain with desired, however emergent, properties of a DLS, which is a complex and distributed system. They point out and justify, with facts and analysis, current misconceptions about the blockchain and DLSs. They describe challenges that these systems will need to address and possible solution avenues for achieving trustworthiness. Findings - Many of the statements that have appeared on the internet, news and academic articles, such as immutable ledger and exact copies, may be misleading. These are desired emergent properties of a complex system, not assured properties. It is well-known within the distributed systems and critical software community that it is extremely hard to prove that a complex system correctly and completely implements emergent properties. Further research and development for trustworthy DLS design and implementation is needed, both practical and theoretical. Research limitations/implications - This is the first known published attempt at describing current misconceptions about blockchain technologies. Further collaborative work, discussions, potential solutions, evaluations, resulting publications and verified reference implementations are needed to ensure DLTs are safe, secure, and trustworthy. Practical implications - Interdisciplinary teams with members from academia, business and industry, and from disciplines such as business, entrepreneurship, theoretical and practical computer science, cybersecurity, finance, mathematics and statistics, must be formed. Such teams must collaborate with the objective of developing strategies and techniques for ensuring the correctness and security of future DLSs in which our society may become dependent. Originality value - The value and originality of this article is twofold: the disproving, through fact collection and systematic analysis, of current misconceptions about the properties of the blockchain and DLSs, and the discussion of challenges to achieving adequate trustworthiness along with the proposal of general avenues for possible solutions.
Chao Yuan, Mixue Xu, Xueming Si, Бин Ли
As a recently proposed public key primitive, attribute-base encryption(ABE) divided into Ciphertext-policy ABE (CP-ABE) and Key-policy ABE (KP-ABE) is a highly promising tool for the management and protection of data. And Blockchain, as one of the core technologies of Bitcoin that is the most representative cryptocurrency, has received extensive attentions recently. Supervision and privacy protection are two difficulties in blockchain. In this paper, a new scheme combining blockchain and accountable CP-ABE is proposed. In this scheme, each change of the data is recorded on the blockchain. And the different permissions of access are realized through ABE. If a malicious user shares a decryption key illegally, it will be considered illegal. Similarly, if the authority generates a decryption key for any unauthorized user, it also will be considered illegal. This scheme allows any third party to publicly verify the identity of a decryption key. And it is achievable for an auditor to publicly audit whether a malicious user or the authority should be responsible for an exposed decryption key, and the key abuser cannot deny it. At last this scheme is applied to the management of electronic documents.
Nejc Zupan, Kaiwen Zhang, Hans‐Arno Jacobsen
Since the introduction of Bitcoin in 2008, blockchain systems have evolved immensely in terms of performance and usability. There is a massive focus on building enterprise blockchain solutions, with providers such as IBM and Microsoft already providing Blockchain-as-a Service (BaaS). To facilitate the adoption of blockchain technologies across various business verticals, we argue that middleware plays an integral role in accelerating the development of automated business processes (i.e., smart contracts). We argue that decentralized messaging is a key requirement of many distributed applications and should be provided as a reusable blockchain middleware. Our system, called HyperPubSub, provides decentralized publish/subscribe messaging for a multi-federated, permissioned, environment. HyperPubSub provides secure and privacy-preserving messaging, which is audited using blockchains for validation and monetization purposes. We demonstrate our implementation using Kafka and Hyperledger.
Areej M. Abduldaim, Jumana Waleed, Arbah S. Abdul-Kareem, Maiada N. Mohmmedali
A zero knowledge proof is a type of authentication scheme, which gives no knowledge beyond the authenticity for identifying an entity. Ring theory plays an important role in designing of a novel algorithm for zero knowledge proof through using of a particular class of non-commutative rings. In this article, we employ the notion of nil 3-Armendariz rings to plan a new algorithm for zero knowledge proof. Our main approach is to build the algebraic structure of the zero knowledge proof depends on the stipulation in the definition of the nil 3-Armendariz rings. The proposed protocol is clarified via numerical simulation example, and its soundness and completeness are evidenced. Finally, we found that the proposed protocol satisfies the completeness, the soundness in the sense that, there is 50% chance of catching a cheating prove, and the proposed protocol has the property of zero knowledge.
Safdar Hussain Shaheen, Muhammad Yousaf, Mudassar Jalil
In this article, a secure and verifiable electronic voting scheme is proposed. Encrypted votes are accumulated and prepared in the form of block on each electronic polling booth at the end of polling time. The resultant block from each electronic polling booth is distributed to the authorized nodes of group for temper proof block chaining that assures the internal verifiability. The external verifiability is attained through the redistribution of temper proof Blockchain ledger to the validated and authorized nodes of auditing group. The temper proof property of electoral data is achieved using an emerging Blockchain Technology. Whereas the secure data distribution in the form of temper proof blocks and ledger amongst the authenticated group members is accomplished through the cryptographically secure group oriented scenario. The individual and universal verifiability features in our proposed scheme make the electoral process transparent, reliable and verifiable.
Elham Akbari, Qing Wu, Wenbing Zhao, Hamid R. Arabnia · 5 authors
Blockchain is one of the hottest topics in the discussion of technologies lately. As the enabling technology for Bitcoin, the pioneering cryptocurrency, blockchain is an append-only distributed ledger that is virtually impossible to attack given sufficient scale of participants. Hence, blockchain holds great promises as the fundamental technology to enable Internet-based electronic voting. However, Internet-based voting has additional requirements than monetary transactions. In this paper, we analyze these requirements, review existing proposed solutions, and outline possible improvements. Specifically, we propose to use live biometrics of the voter to perform secure and highly reliable remote authentication. We also propose a scheme to protect the secrecy of the ballots and eliminate the influence of votes already cast. Finally, we propose to impose a hierarchy to the voting infrastructure that aligns naturally with traditional voting, which enables parallel processing of multiple blockchains, to overcome the intrinsic scalability limitation of the blockchain technology.
Fangdong Zhu, Wen Chen, Yunpeng Wang, Ping Lin · 7 authors
Online wallet has become an important method to manage Bitcoin. In a Bitcoin transaction, online wallet manages the private key automatically, and stores the encrypted private key in remote to ensure the accessibility of Bitcoin anywhere. In the traditional online wallet, the private key is stored centrally in a storage unit. However, if the storage unit is collapsed or hacked, users will suffer the risk of losing their Bitcoins. Motivated by this, in this paper, we propose a new online wallet architecture: HA-eWallet. In HA-eWallet, the transaction of Bitcoin is signed by multiple private keys rather than one, and private keys are stored separately in different places. In addition, we introduce a second service unit to construct the Active-Active architecture to rotate the capability and workload. Besides, we adopt a disaster recovery strategy in our proposed architecture in case of any disaster. According to the running states of each service unit, HA-eWallet have three operation models, and can be switched smoothly. Theoretical analyses and experiments show that: HA-eWallet can achieve higher availability compared with the traditional online wallet architecture, and users will not suffer a loss as long as the number of lost private keys are less than 50% of the users' total number of private keys.