Blockchain Papers

Benjamin Terner

No abstract is available for this record.

Joshua S. Gans, Richard Holden

Blockchain consensus is a state whereby each node in a network agrees on the current state of the blockchain. Existing protocols achieve consensus via a contest or voting procedure to select one node as a dictator to propose new blocks. However, this procedure can still lead to potential attacks that make consensus harder to achieve or lead to coordination issues if multiple, competing chains (i.e., forks) are created with the potential that an untruthful fork might be selected. We explore the potential for mechanisms to be used to achieve consensus that are triggered when there is a dispute impeding consensus. Using the feature that nodes stake tokens in proof of stake (POS) protocols, we construct revelation mechanisms in which the unique (subgame perfect) equilibrium involves validating nodes propose truthful blocks using only the information that exists amongst all nodes. We construct operationally and computationally simple mechanisms under both Byzantine Fault Tolerance and a Longest Chain Rule, and discuss their robustness to attacks. Our perspective is that the use of simple mechanisms is an unexplored area of blockchain consensus and has the potential to mitigate known trade-offs and enhance scalability.

Jovan Karamachoski, Liljana Gavrilovska

No abstract is available for this record.

Sudeep Tanwar

No abstract is available for this record.

Emanuel Onica, Ciprian Amariei

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.

Yanhe Na, Zhan Wen, Jie Fang, Yin Tang · 5 authors

The Practical Byzantine Fault Tolerant (PBFT) consensus algorithm has many advantages, which makes PBFT utilized widely. Nonetheless, PBFT is not suitable for large-scale node scenarios due to its high communication complexity and it also has an apparent disadvantage of inadequate fault tolerance. The typically derived PBFT algorithms focus on reducing communication complexity at the cost of diminished system security or fault tolerance. In this paper, Dual-Primary-Node derived Practical Byzantine Fault Tolerance (DPNPBFT) is proposed to achieve the best balance of the above three performances. First, DPNPBFT selects dual master nodes based on the idea of power separation. The two master nodes check balance and supervise each other to avoid excessive centralization as a single master node system. It also reduces the communication complexity of the replica node, which only communicates with the master node. Furthermore, we designed the architecture of DPNPBFT to get a practical 49% fault tolerance rate, and it is close to the current mainstream Proof of Work and Proof of Stake algorithms. Experimental results demonstrate that DPNPBFT has O(N) level communication complexity and excellent anti-host node malicious performance. The Transactions Per Second of DPNPBFT is stable at 1700. It proves DPNPBFT has the best performance balance and excellent comprehensive performance for large-scale Internet of Things application scenarios.

Kaifeng Zhang, Zhao Qiu, Tao Chen, Jiale Lin · 11 authors

No abstract is available for this record.

Sebastian Müller, Andreas Penzkofer, Nikita Polyanskii, Jonas Theis · 6 authors

We introduce the theoretical foundations of the Tangle 2.0, a probabilistic leaderless consensus protocol based on a directed acyclic graph (DAG) called the Tangle. The Tangle naturally succeeds the blockchain as its next evolutionary step as it offers features suited to establish more efficient and scalable distributed ledger solutions. Consensus is no longer found in the longest chain but on the heaviest DAG, where PoW is replaced by a stake- or reputation-based weight function. The DAG structure and the underlying Reality-based UTXO Ledger allow parallel validation of transactions without the need for total ordering. Moreover, it enables the removal of the intermediary of miners and validators, allowing a pure two-step process that follows the \emph{propose-vote} paradigm at the node level and not at the validator level. We propose a framework to analyse liveness and safety under different communication and adversary models. This allows providing impossibility results in some edge cases and in the asynchronous communication model. We provide formal proof of the security of the protocol assuming a common random coin.

Zerui Ge, Dumitrel Loghin, Beng Chin Ooi, Pingcheng Ruan · 5 authors

With the emergence of hybrid blockchain database systems, we aim to provide an in-depth analysis of the performance and trade-offs among a few representative systems. To achieve this goal, we implement Veritas and BlockchainDB from scratch. For Veritas, we provide two flavors to target the crash fault-tolerant (CFT) and Byzantine fault-tolerant (BFT) application scenarios. Specifically, we implement Veritas with Apache Kafka to target CFT application scenarios, and Veritas with Tendermint to target BFT application scenarios. We compare these three systems with the existing open-source implementation of BigchainDB. BigchainDB uses Tender-mint for consensus and provides two flavors: a default implementation with blockchain pipelining and an optimized version that includes blockchain pipelining and parallel transaction validation. Our experimental analysis confirms that CFT designs, which are typically used by distributed databases, exhibit much higher performance than BFT designs, which are specific to blockchains. On the other hand, our extensive analysis highlights the variety of design choices faced by the developers and sheds some light on the trade-offs that need to be done when designing a hybrid blockchain database system.

Margarita Capretto, Martín Ceresa, César Sánchez

Blockchains are modern distributed systems that provide decentralized financial capabilities with trustable guarantees. Smart contracts are programs written in specialized programming languages running on a blockchain and govern how tokens and cryptocurrency are sent and received. Smart contracts can invoke other contracts during the execution of transactions initiated by external users. Once deployed, smart contracts cannot be modified and their pitfalls can cause malfunctions and losses, for example by attacks from malicious users. Runtime verification is a very appealing technique to improve the reliability of smart contracts. One approach consists of specifying undesired executions (never claims) and detecting violations of the specification on the fly. This can be done by extending smart contracts with additional instructions corresponding to monitor specified properties, resulting in an onchain monitoring approach. In this paper, we study transaction monitoring that consists of detecting violations of complete transaction executions and not of individual operations within transactions. Our main contributions are to show that transaction monitoring is not possible in most blockchains and propose different execution mechanisms that would enable transaction monitoring.

Liang Cai, Qilei Li, Xiubo Liang

No abstract is available for this record.

Liang Cai, Qilei Li, Xiubo Liang

No abstract is available for this record.

Andras Ferenczi, Costin Bădică

No abstract is available for this record.

Sylvain Carré, Franck Gabriel

No abstract is available for this record.

Γεώργιος Δρακόπουλος, Eleanna Kafeza, Ιωάννα Γιαννούκου, Phivos Mylonas · 5 authors

No abstract is available for this record.

Sneha Sarkar, Dharavath Ramesh, Hemika Jadav Badavath

No abstract is available for this record.

Sanatan Shrivastava, Ashish Sharma

No abstract is available for this record.

Imran Bashir

This chapter covers blockchain age protocols. Some novel and some variants of classical blockchain consensus protocols were discussed in Chapter 7 . We start with Ethereum and finish this chapter at Solana. Along the way, we will cover in detail the characteristics, strengths, weaknesses, properties, and inner workings of major consensus protocols used in platforms such as Cosmos, Ethereum 2.0, and Polkadot.

Imran Bashir

Blockchain consensus is the core element of a blockchain, which ensures the integrity and consistency of the blockchain data. Blockchain being a distributed system, in the first instance, it may appear that we can apply traditional distributed consensus protocols, such as Paxos or PBFT, to address the agreement and total order requirements in a blockchain. However, this can only work in consortium chains where participants are known and limited in number. In public chains, traditional consensus protocols cannot work due to the permissionless environment. However, in 2008 a new class of consensus algorithms emerged which relied on proof of work to ensure random leader election who wins the right to append to the blockchain by solving a mathematical puzzle. This is the so-called Nakamoto consensus protocol. This algorithm for the very first time solved the problem of consensus in a permissionless public environment with many anonymous participants.

Xiaoqin Feng, Jianfeng Ma, Yinbin Miao, Ximeng Liu · 5 authors

Proof of Stake powered blockchains account for general trends in existing consensus mechanisms. However, existing PoS protocols are vulnerable to the nothing at stake and long range attacks, which allow attackers to gain unfair shares based on costless simulations and malicious sale information. In a decentralized setting, these securities are limited as each node is unregulated. To address these problems, we introduce a proof-of-hardware-stake (PohS) consensus mechanism and a regulatory mechanism based on a consortium blockchain. Our approach is implemented in a sharding blockchain to scale the consensus. Since any node on the network cannot fake information, the blockchain trustless won not be decreased by the reliance on a consortium blockchain. Under the competing rule of PohS consensus mechanism, adversaries can issue the long range attack with at most$10^{-3}$probability. The regulatory mechanism implements the regulation of costless simulations at the nothing stake attack. We prove that our design is secure (e.g.,51% and selfish mining) against adversarial stakes less than 51% by adopting the square root of stakes for competition. Our proof also highlights the security of double-spending and long range attacks. Simulations are conducted to compare the efficiency of our approach with Ethereum and Ouroboros.

Daria Smuseva, Ivan Malakhov, Andrea Marin, Aad van Moorsel · 5 authors

No abstract is available for this record.

David Guzman, Dirk Trossen, Mike McBride, Xinxin Fan

No abstract is available for this record.

M.D. Khan, Dirk Schaefer, Jelena Milisavljevic-Syed

Blockchain Technology has gained prominence since 2008 with trust, reliability, speed, and transparency becoming major advantages. It has also been applied and researched within a multitude of industry applications ranging from manufacturing to financial transactions through to real estate. In addition to Artificial Intelligence (AI) and Internet of Things (IoT), Distributed Ledger Technology (DLT) such as blockchain serves as the backbone to the Machine Economy, which is a relatively recent concept in which machines can communicate and exchange data with each other autonomously, allowing manufacturing companies to become more competitive. However, using blockchain for exchanging large volumes of data requires significant fees and energy due to its use of miners to validate transactions which is a barrier for manufacturing companies to implement. Directed Acyclic Graph (DAG), which is a different type of DLT is an example of an alternative to blockchain which aims to overcome most of the problems currently on the blockchain and promises to enable fee-less transactions with much lower power requirements than blockchain. In this paper, the authors explore the DLT aspect of the machine economy within the manufacturing context. Firstly, the enabling DLT technical attributes of the machine economy are analysed. This is followed by an evaluation of all DLT’s, focusing on the challenges and benefits of each alternative. Following on from this, a cross comparison of each DLT type is done which leads into a discussion and future directions to be drawn.

Xin Wang, Sisi Duan, James R. Clavin, Haibin Zhang

A blockchain is a distributed system that achieves strong security guarantees in storing, managing, and processing data. All blockchains achieve a common goal: building a decentralized system that provides a trustworthy service in an untrustworthy environment. A blockchain builds a Byzantine fault-tolerant (BFT) system in which decentralized nodes run a protocol to reach an agreement on the common system state. In this article, we focus on the research of BFT protocols. In particular, we categorize BFT protocols according to both the system models and workflow. We seek to answer these important questions: How has the research in BFT evolved in the past four decades, especially with the rise of blockchains? What are the driven needs for BFT research in the future?