Blockchain Papers

Bo Qin, Jikun Huang, Qin Wang, Xizhao Luo · 6 authors

No abstract is available for this record.

Daniel Augot, Hervé Chabanne, Olivier Clémot, William R. George

The most fundamental purpose of blockchain technology is to enable\npersistent, consistent, distributed storage of information. Increasingly common\nare authentication systems that leverage this property to allow users to carry\ntheir personal data on a device while a hash of this data is signed by a\ntrusted authority and then put on a blockchain to be compared against. For\ninstance, in 2015, MIT introduced a schema for the publication of their\nacademic certificates based on this principle. In this work, we propose a way\nfor users to obtain assured identities based on face-to-face proofing that can\nthen be validated against a record on a blockchain. Moreover, in order to\nprovide anonymity, instead of storing a hash, we make use of a scheme of Brands\nto store a commitment against which one can perform zero-knowledge proofs of\nidentity. We also enforce the confidentiality of the underlying data by letting\nusers control a secret of their own. We show how our schema can be implemented\non Bitcoin's blockchain and how to save bandwidth by grouping commitments using\nMerkle trees to minimize the number of Bitcoin transactions that need to be\nsent. Finally, we describe a system in which users can gain access to services\nthanks to the identity records of our proposal.\n

B. K. Kipkirui

The Elliptic Curve Digital Signature Algorithm (ECDSA), de nes a technique for generating and validating digital signatures. We start by reviewing the mathematics behind the Digital Signature Algorithm (DSA) and its elliptic curve analogue (ECDSA). Secondly, we describe how the ECDSA is used in Bitcoin technology.

Quanqing Xu, Chao Jin, Mohamed Faruq Bin Mohamed Rasid, Bharadwaj Veeravalli · 5 authors

No abstract is available for this record.

Maxim Amelchenko, Shlomi Dolev

Blockchain's ever increasing size has become a major problem. Bitcoin [7], for example, has grown to 115120 MB as of May 2017, which is roughly 115 GB. This uncontrollable growth of the Blockchain is bound to become an issue in the future, as hard disks may become too small to store the entire Blockchain history and traversing the transactions databases may become increasingly slow. Already, there are lightweight clients in various Blockchain platforms (Bitcoin included), who do not store the entire chain locally but rely on a third party to send them the blocks they need. There are many issues with these clients, mainly security problems, since they go back to trusting a central authority rather than gaining trust from several distributed peers. These clients' knowledge of the Blockchain is solely based on some third party that should be trusted, while the conceptual base for Blockchain is trust distributing. In this paper we present two Blockchain abbreviation schemes. The first one is based on the Ethereum [8] project and proposes replacing the full Blockchain with a new Genesis block, which summarizes everyone's account balances at a certain point in time. One possible benefit is to use less communication while still storing the prefix of the old Blockchain (or signature of the Blockchain that can validate a version archived by other participants) in a local archive. Here we trade loss of transaction history for efficiency. Our second contribution is a UNIX based architecture using the file system, for implementing Blockchain. We demonstrate a Blockchain abbreviation technique for this architecture too.

Long-Hai Li, Chengqiang Huang, Shao-Feng Fu

A mix-net is an important cryptographic tool in schemes requiring anonymity of messages, such as in secure e-voting and e-auction schemes. In this paper, we present a novel mix-net protocol which achieves stronger security and satisfies both public verifiability and sender verifiability. Our mix-net is constructed based on Wikström's scheme and strengthens its se-curity by introducing an improved key generation procedure and proposing a new method for constructing zero knowledge proof of secret shuffle. It is proved to be CCA-secure under the assumption of random oracle. Compared with previous mix-net schemes which are CCA-secure, the proposed protocol does not require any trusted center, and incurs fewer inter-actions between servers which resulting in a lower computation and communication complexity.

Nesrine Kaaniche, Maryline Laurent

Recent years have witnessed the trend of increasingly relying on distributed infrastructures. This increased the number of reported incidents of security breaches compromising users' privacy, where third parties massively collect, process and manage users' personal data. Towards these security and privacy challenges, we combine hierarchical identity based cryptographic mechanisms with emerging blockchain infrastructures and propose a blockchain-based data usage auditing architecture ensuring availability and accountability in a privacy-preserving fashion. Our approach relies on the use of auditable contracts deployed in blockchain infrastructures. Thus, it offers transparent and controlled data access, sharing and processing, so that unauthorized users or untrusted servers cannot process data without client's authorization. Moreover, based on cryptographic mechanisms, our solution preserves privacy of data owners and ensures secrecy for shared data with multiple service providers. It also provides auditing authorities with tamper-proof evidences for data usage compliance.

David Froelicher, Patricia Egger, João Sá Sousa, Jean Louis Raisaro · 8 authors

Abstract Current solutions for privacy-preserving data sharing among multiple parties either depend on a centralized authority that must be trusted and provides only weakest-link security (e.g., the entity that manages private/secret cryptographic keys), or leverage on decentralized but impractical approaches (e.g., secure multi-party computation). When the data to be shared are of a sensitive nature and the number of data providers is high, these solutions are not appropriate. Therefore, we present U n L ynx , a new decentralized system for efficient privacy-preserving data sharing. We consider m servers that constitute a collective authority whose goal is to verifiably compute on data sent from n data providers. U n L ynx guarantees the confidentiality, unlinkability between data providers and their data, privacy of the end result and the correctness of computations by the servers. Furthermore, to support differentially private queries, U n L ynx can collectively add noise under encryption. All of this is achieved through a combination of a set of new distributed and secure protocols that are based on homomorphic cryptography, verifiable shuffling and zero-knowledge proofs. U n L ynx is highly parallelizable and modular by design as it enables multiple security/privacy vs. runtime tradeoffs. Our evaluation shows that U n L ynx can execute a secure survey on 400,000 personal data records containing 5 encrypted attributes, distributed over 20 independent databases, for a total of 2,000,000 ciphertexts, in 24 minutes.

Alican Beydemir, İbrahim Soğukpınar

Importance of Internet of Things technologies increased in recent years. However, these technologies carry some security vulnerabilities because of their network communication layer. The root cause of these vulnerabilities is usually the Authentication problem. Zero knowledge proof method is a strong cryptographic solution for Authentication problem that is proving of having a knowledge to another party without revealing anything other than the veracity of the statement. Zero knowledge proof method is consist of two-way complex mathematical algorithms for both parties. In this work, a new method that uses zero knowledge proofs has been proposed to provide efficient solution for Internet of Things technologies. New method was implemented and tested, then compared with existing proposed zero knowledge proof based authentication methods.

Yi Liu, Ruilin Li, Xingtong Liu, Jian Wang · 7 authors

With widely adoption of Bitcoin, Many malicious software trying to steal bitcoins through network has emerged in a large scale. Bitcoin makes heavy use of elliptic curve digital signature algorithm to guarantee transactions security. Each user can have lots of addresses hashed from his public keys to receive coins, and need private keys associated with these addresses to authorize spending those coins. A Bitcoin wallet give a good assistance to manage and preserve all private keys belong to its owner. However, saving complete private keys on local storage meets a big challenge in case of theft. For the purpose of securing user's private keys, we propose an efficient method to enhance Bitcoin wallet security. We combine random seeds and a passphrase for user easy to keep in mind to generate private keys whenever needed. It is only need to reserve a list of random seeds on local storage instead of complete private keys. Nobody could generate the whole private keys just relying on random seeds without the passphrase. Therefore, our method increases the difficulty for attackers to steal bitcoins. We also introduce a key recovery approach in case of the passphrase being forgotten. Our method does not incur any additional operations and is convenient to use by a common customer without professional knowledge.

Xueping Liang, Juan Zhao, Sachin Shetty, Danyi Li

Data assurance and resilience are crucial security issues in cloud-based IoT applications. With the widespread adoption of drones in IoT scenarios such as warfare, agriculture and delivery, effective solutions to protect data integrity and communications between drones and the control system have been in urgent demand to prevent potential vulnerabilities that may cause heavy losses. To secure drone communication during data collection and transmission, as well as preserve the integrity of collected data, we propose a distributed solution by utilizing blockchain technology along with the traditional cloud server. Instead of registering the drone itself to the blockchain, we anchor the hashed data records collected from drones to the blockchain network and generate a blockchain receipt for each data record stored in the cloud, reducing the burden of moving drones with the limit of battery and process capability while gaining enhanced security guarantee of the data. This paper presents the idea of securing drone data collection and communication in combination with a public blockchain for provisioning data integrity and cloud auditing. The evaluation shows that our system is a reliable and distributed system for drone data assurance and resilience with acceptable overhead and scalability for a large number of drones.

Rifa Hanifatunnisa, Budi Rahardjo

Increasingly digital technology in the present helped many people lives. Unlike the electoral system, there are many conventional uses of paper in its implementation. The aspect of security and transparency is a threat from still widespread election with the conventional system (offline). General elections still use a centralized system, there is one organization that manages it. Some of the problems that can occur in traditional electoral systems is with an organization that has full control over the database and system, it is possible to tamper with the database of considerable opportunities. Blockchain technology is one of solutions, because it embraces a decentralized system and the entire database are owned by many users. Blockchain itself has been used in the Bitcoin system known as the decentralized Bank system. By adopting blockchain in the distribution of databases on e-voting systems can reduce one of the cheating sources of database manipulation. This research discusses the recording of voting result using blockchain algorithm from every place of election. Unlike Bitcoin with its Proof of Work, this thesis proposed a method based on a predetermined turn on the system for each node in the built of blockchain.

Aravind Ramachandran, Murat Kantarcıoğlu

Blockchain technology has evolved from being an immutable ledger of\ntransactions for cryptocurrencies to a programmable interactive the environment\nfor building distributed reliable applications. Although, blockchain technology\nhas been used to address various challenges, to our knowledge none of the\nprevious work focused on using blockchain to develop a secure and immutable\nscientific data provenance management framework that automatically verifies the\nprovenance records. In this work, we leverage blockchain as a platform to\nfacilitate trustworthy data provenance collection, verification, and\nmanagement. The developed system utilizes smart contracts and open provenance\nmodel (OPM) to record immutable data trails. We show that our proposed\nframework can efficiently and securely capture and validate provenance data,\nand prevent any malicious modification to the captured data as long as the\nmajority of the participants are honest.\n

Vincent Gramoli

No abstract is available for this record.

En Zhang, Jie Peng, Ming Li

Secret sharing is an important component of cryptography protocols and has a wide range of practical applications. However, the existing secret sharing schemes cannot apply to computationally weak devices and cannot efficiently guarantee fairness. In this study, a novel outsourcing secret sharing scheme is proposed. In the setting of outsourcing secret sharing, clients only need a small amount of decryption and verification operations, while the expensive reconstruction computation and verifiable computation can be outsourced to cloud service providers (CSP). The scheme does not require complex interactive argument or zero‐knowledge proof. The malicious behaviour of clients and CSP can be detected in time. Moreover, the CSP cannot get any useful information about the secret, and it is fair for every client to obtain the secret. At the end of this study, the authors prove the security of the proposed scheme and compare it with other secret sharing schemes.

Peng Jiang, Fuchun Guo, Kaitai Liang, Jianchang Lai · 5 authors

No abstract is available for this record.

Qin Wang, Bo Qin, Jiankun Hu, Fu Xiao

No abstract is available for this record.

Robert Herian

Abstract There are important synergies between the trust of blockchain and that of trusts law. This article critically examines the intersection between law and blockchain technology through an exploration of the notional impacts upon orthodox practices and principles of trusts law made by blockchain and other “disruptive” technologies, including smart property and the Internet of Things.

C. E. Veni Madhavan, Ch. Srikanth, H.V. Kumar Swamy

We present a computational system for handling, in an integrated manner, distributed transactional information and the associated monetary payment information, arising in typical organizational applications. Our paper contains three ideas: (i) a conceptual architectural design for chains of blocks of content transaction chains, (ii) a conceptual architectural design for blocks of financial instrument transaction chains including a proposed form of denominational digital cash, and (iii) a new, versatile cryptographic hash function to support all the chaining operations. In the total design, the transactional and financial information are chained together. We call these chains the VSK chains. Our system consists of centralized, auditable chains to manage distributed transactions of: (i) financial instruments (such as coins, tokens, or coupons used as a medium of exchange) and (ii) associated transactions of plain content (such as documents, or mail). The digital cash and the blockchains of our system can be adapted to models of decentralized blockchains, akin to cryptocurrencies, using proof-of-work/proof-of-stake computational principles. We have recently proposed a new key stream generator based on certain types of collections of arithmetic progressions of integers. Our scheme provides for enhanced flexibility and versatility with respect to parametric choices.We build our hashchains using the integer sequences derived from this collection. We present an outline of prototype development and implementation of certain modules of the VSK chains system.

Christian Cachin

A blockchain is a public ledger for recording transactions, maintained by<br> many nodes without central authority through a distributed cryptographic<br> protocol. All nodes validate the information to be appended to the<br> blockchain, and a consensus protocol ensures that the nodes agree on a<br> unique order in which entries are appended. Consensus protocols for<br> tolerating Byzantine faults have received renewed attention because they<br> also address blockchain systems. However, amid the current hype around<br> blockchains, cryptocurrencies, fintech startups, and novel consensus<br> mechanisms, it is sometimes overlooked that assessing and gaining<br> confidence in the resilience of a protocol is a difficult task. We argue that developing consensus protocols is similar to engineering<br> cryptographic systems, and that blockchain developers should look towards<br> the established experience in cryptography and security with building<br> trustworthy systems. Otherwise, it might be dangerous to entrust<br> financial value to new protocols. Public discussion, expert reviews,<br> broad validation, and standards recommendations should be employed,<br> following the established practice in cryptography and security.<br>

Authors unavailable

This document describes the Schnorr non-interactive zero-knowledge (NIZK) proof, a non-interactive variant of the three-pass Schnorr identification scheme. The Schnorr NIZK proof allows one to prove the knowledge of a discrete logarithm without leaking any information about its value. It can serve as a useful building block for many cryptographic protocols to ensure that participants follow the protocol specification honestly. This document specifies the Schnorr NIZK proof in both the finite field and the elliptic curve settings.

Dimitris Chatzopoulos, Mahdieh Ahmadi, Sokol Kosta, Pan Hui

During the last years, researche'rs have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that integrates an incentive scheme and a reputation mechanism. Our proposal follows the principles of the Hidden Market Design approach, which allows users to specify the amount of resources they are willing to sacrifice when participating in the offloading system. The underlying algorithm, that users are not aware of, is based on a truthful auction strategy and a peer-to-peer reputation exchange scheme. Extensive simulations on real traces depict how our designed mechanism achieves higher offloading rate and produces less traffic compared to three benchmark algorithms. Finally, we show how collaborating devices get rewarded for their contribution, while selfish ones get sidelined by others.

Diego Romano, Giovanni Schmid

After more than eight years since the launch of Bitcoin, the decentralized transaction ledger functionality implemented through the blockchain technology is being used not only for cryptocurrencies, but to register, confirm and transfer any kind of contract and property. In this work, we analyze the most relevant functionalities and known issues of this technology, with the intent of pointing out the possible behaviours that are not as efficient and reliable as they should be when thinking with a broader outlook.

Carlos Oliver, Alessandro Ricottone, Pericles Philippopoulos

We propose a proof-of-work algorithm that rewards blockchain miners for using computational resources to solve NP-complete puzzles. The resulting blockchain will publicly store and improve solutions to problems with real world applications while maintaining a secure and fully functional transaction ledger.