107 research outputs found
Fair and trustworthy: Lock-free enhanced tendermint blockchain algorithm
Blockchain Technology is exclusively used to make online transactions secure by maintaining a distributed and decentralized ledger of records across multiple computers. Tendermint is a general-purpose blockchain engine that is composed of two parts; Tendermint Core and the blockchain application interface. The application interface makes Tendermint suitable for a wide range of applications. In this paper, we analyze and improve Practical Byzantine Fault Tolerant (PBFT), a consensus-based Tendermint blockchain algorithm. In order to avoid negative issues of locks, we first propose a lock-free algorithm for blockchain in which the proposal and voting phases are concurrent whereas the commit phase is sequential. This consideration in the algorithm allows parallelism. Secondly, a new methodology is used to decide the size of the voter set which is a subset of blockchain nodes, further investigating the block sensitivity and trustworthiness of nodes. Thirdly, to fairly select the voter set nodes, we employ the random walk algorithm. Fourthly, we imply the wait-freedom property by using a timeout due to which all blocks are eventually committed or aborted. In addition, we have discussed voting conflicts and consensuses issues that are used as a correctness property, and provide some supportive techniques
Correctness of Tendermint-Core Blockchains
Tendermint-core blockchains (e.g. Cosmos) are considered today one of the most viable alternatives for the highly energy consuming proof-of-work blockchains such as Bitcoin and Ethereum. Their particularity is that they aim at offering strong consistency (no forks) in an open system combining two ingredients (i) a set of validators that generate blocks via a variant of Practical Byzantine Fault Tolerant (PBFT) consensus protocol and (ii) a selection strategy that dynamically selects nodes to be validators for the next block via a proof-of-stake mechanism. The exact assumptions on the system model under which Tendermint underlying algorithms are correct and the exact properties Tendermint verifies, however, have never been formally analyzed. The contribution of this paper is as follows. First, while formalizing Tendermint algorithms we precisely characterize the system model and the exact problem solved by Tendermint, then, we prove that in eventual synchronous systems a modified version of Tendermint solves (i) under additional assumptions, a variant of one-shot consensus for the validation of one single block and (ii) a variant of the repeated consensus problem for multiple blocks. These results hold even if the set of validators is hit by Byzantine failures, provided that for each one-shot consensus instance less than one third of the validators is Byzantine
On Fairness in Committee-Based Blockchains
Committee-based blockchains are among the most popular alternatives of proof-of-work based blockchains, such as Bitcoin. They provide strong consistency (no fork) under classical assumptions, and avoid using energy-consuming mechanisms to add new blocks in the blockchain. For each block, these blockchains use a committee that executes Byzantine-fault tolerant distributed consensus to decide the next block they will add in the blockchain. Unlike Bitcoin, where there is only one creator per block, in committee-based blockchain any block is cooperatively created. In order to incentivize committee members to participate in the creation of new blocks, rewarding schemes have to be designed. In this paper, we study the fairness of rewarding in committee-based blockchains and we provide necessary and sufficient conditions on the system communication under which it is possible to have a fair reward mechanism
Consensus Algorithms of Distributed Ledger Technology -- A Comprehensive Analysis
The most essential component of every Distributed Ledger Technology (DLT) is
the Consensus Algorithm (CA), which enables users to reach a consensus in a
decentralized and distributed manner. Numerous CA exist, but their viability
for particular applications varies, making their trade-offs a crucial factor to
consider when implementing DLT in a specific field. This article provided a
comprehensive analysis of the various consensus algorithms used in distributed
ledger technologies (DLT) and blockchain networks. We cover an extensive array
of thirty consensus algorithms. Eleven attributes including hardware
requirements, pre-trust level, tolerance level, and more, were used to generate
a series of comparison tables evaluating these consensus algorithms. In
addition, we discuss DLT classifications, the categories of certain consensus
algorithms, and provide examples of authentication-focused and
data-storage-focused DLTs. In addition, we analyze the pros and cons of
particular consensus algorithms, such as Nominated Proof of Stake (NPoS),
Bonded Proof of Stake (BPoS), and Avalanche. In conclusion, we discuss the
applicability of these consensus algorithms to various Cyber Physical System
(CPS) use cases, including supply chain management, intelligent transportation
systems, and smart healthcare.Comment: 50 pages, 20 figure
LightChain: A DHT-based Blockchain for Resource Constrained Environments
As an append-only distributed database, blockchain is utilized in a vast
variety of applications including the cryptocurrency and Internet-of-Things
(IoT). The existing blockchain solutions have downsides in communication and
storage efficiency, convergence to centralization, and consistency problems. In
this paper, we propose LightChain, which is the first blockchain architecture
that operates over a Distributed Hash Table (DHT) of participating peers.
LightChain is a permissionless blockchain that provides addressable blocks and
transactions within the network, which makes them efficiently accessible by all
the peers. Each block and transaction is replicated within the DHT of peers and
is retrieved in an on-demand manner. Hence, peers in LightChain are not
required to retrieve or keep the entire blockchain. LightChain is fair as all
of the participating peers have a uniform chance of being involved in the
consensus regardless of their influence such as hashing power or stake.
LightChain provides a deterministic fork-resolving strategy as well as a
blacklisting mechanism, and it is secure against colluding adversarial peers
attacking the availability and integrity of the system. We provide mathematical
analysis and experimental results on scenarios involving 10K nodes to
demonstrate the security and fairness of LightChain. As we experimentally show
in this paper, compared to the mainstream blockchains like Bitcoin and
Ethereum, LightChain requires around 66 times less per node storage, and is
around 380 times faster on bootstrapping a new node to the system, while each
LightChain node is rewarded equally likely for participating in the protocol
A New Product Anti-Counterfeiting Blockchain Using a Truly Decentralized Dynamic Consensus Protocol
The growth of counterfeit goods has plagued the international community for decades. Nowadays, the battle against counterfeiting remains a significant challenge. Most of the current anti‐counterfeiting systems are centralized. Motivated by the evolution of blockchain technology, we propose (Block‐Supply), a decentralized anti‐counterfeiting supply chain that exploits NFC and blockchain technologies. This paper also proposes a new truly decentralized consensus protocol that, unlike most of the existing protocols, does not require PoW and randomly employs a different set of different size of validators each time a new block is proposed. Our protocol utilizes a game theoretical model to analyze the risk likelihood of the block\u27s proposing nodes. This risk likelihood is used to determine the number of validators involved in the consensus process. Additionally, the game model enforces the honest consensus nodes\u27 behavior by rewarding honest players and penalizing dishonest ones. Our protocol utilizes a novel, decentralized, dynamic mapping between the nodes that participate in the consensus process. This mapping ensures that the interaction between these nodes is executed anonymously and blindly. This way of mapping withstands many attacks that require knowing the identities of the participating nodes in advance, such as DDoS, Bribery, and Eclipse attacks
Threshold Encrypted Mempools: Limitations and Considerations
Encrypted mempools are a class of solutions aimed at preventing or reducing
negative externalities of MEV extraction using cryptographic privacy. Mempool
encryption aims to hide information related to pending transactions until a
block including the transactions is committed, targeting the prevention of
frontrunning and similar behaviour. Among the various methods of encryption,
threshold schemes are particularly interesting for the design of MEV mitigation
mechanisms, as their distributed nature and minimal hardware requirements
harmonize with a broader goal of decentralization.
This work looks beyond the formal and technical cryptographic aspects of
threshold encryption schemes to focus on the market and incentive implications
of implementing encrypted mempools as MEV mitigation techniques. In particular,
this paper argues that the deployment of such protocols without proper
consideration and understanding of market impact invites several undesired
outcomes, with the ultimate goal of stimulating further analysis of this class
of solutions outside of pure cryptograhic considerations. Included in the paper
is an overview of a series of problems, various candidate solutions in the form
of mempool encryption techniques with a focus on threshold encryption,
potential drawbacks to these solutions, and Osmosis as a case study. The paper
targets a broad audience and remains agnostic to blockchain design where
possible while drawing from mostly financial examples
Lessons from HotStuff
This article will take you on a journey to the core of blockchains, their
Byzantine consensus engine, where HotStuff emerged as a new algorithmic
foundation for the classical Byzantine generals consensus problem.
The first part of the article underscores the theoretical advances HotStuff
enabled, including several models in which HotStuff-based solutions closed
problems which were opened for decades.
The second part focuses on HotStuff performance in real life setting, where
its simplicity drove adoption of HotStuff as the golden standard for blockchain
design, and many variants and improvements built on top of it.
Both parts of this document are meant to describe lessons drawn from HotStuff
as well as dispel certain myths
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