This study builds on our previous systematic literature review (SLR) that assessed the applications and performance of zk-SNARK, zk-STARK, and Bulletproof non-interactive zero-knowledge proof (NIZKP) protocols. To address the identified research gaps, we designed and implemented a benchmark comparing these three protocols using a dynamic minimized multiplicative complexity (MiMC) hash application. We evaluated performance across four general-purpose programming libraries and two programming languages. Our results show that zk-SNARK produced the smallest proofs, while zk-STARK generated the largest. In terms of proof generation and verification times, zk-STARK was the fastest, and Bulletproof was the slowest. Interestingly, zk-SNARK proofs verified marginally faster than zk-STARK, contrary to other findings. These insights enhance our understanding of the functionality, security, and performance of NIZKP protocols, providing valuable guidance for selecting the most suitable protocol for specific applications.
En el ecosistema de las aplicaciones descentralizadas (DApps), la dependencia de un único nodo de blockchain para realizar todas las transacciones presenta varios desafíos críticos, entre ellos la falta de redundancia y la potencial inestabilidad en caso de fallos en dicho nodo. Este problema subraya la necesidad de un sistema que permita la configuración y monitoreo de múltiples nodos, asegurando una alta disponibilidad y un equilibrio de carga eficiente. El presente Trabajo de Final de Grado, titulado "HIGH AVAILABILITY ETHEREUM-LIKE NODE PROXY", aborda esta problemática proponiendo una solución basada en una aplicación desarrollada en Python para monitorear y equilibrar el tráfico entre varios nodos Ethereum JSON-RPC.
Decentralized Physical Infrastructure Networks (De-PINS) are secured and governed by blockchains but beyond crypto-economic incentives, they lack measures to establish trust in participating devices and their services. The verification of relevant device credentials during device registration helps to overcome this problem. However, on-chain verification in decentralized applications (dApp) discloses potentially confidential device attributes whereas off-chain verification introduces undesirable trust assumptions. In this paper, we propose a credential-based device registration (CDR) mechanism that verifies device credentials on the blockchain and leverages zero-knowledge proofs (ZKP) to protect confidential device attributes from being disclosed. We characterize CDR for DePINs, present a general system model, and technically evaluate CDR using zkSNARKs with Groth16 [1] and Marlin [2]. Our experiments give first insights into performance impacts and reveal a tradeoff between the applied proof systems.
In this paper, we present a decentralized network protocol, Space Network Protocol, based on Communication Satellite Services. The protocol outlines a method for distributing information about the status of satellite communication services across the entire blockchain network, facilitating fairness and transparency in all communication services. Our primary objective is to standardize the services delivered by all satellite networks under the communication satellite protocol. This standard remains intact regardless of potential unreliability associated with the satellites or the terminal hardware. We proposed PoD (Proof of Distribution) to verify if the communication satellites are online and PoF (Proof of Flow) to authenticate the actual data flow provided by the communication satellites. In addition, we also proposed PoM (Proof of Mesh) to verify if the communication satellites have successfully meshed together. Utilizing zero-knowledge proof and multi-party cryptographic computations, we can evaluate the service provisioning parameters of each satellite, even in the presence of potential terminal or network node fraud. This method offers technical support for the modeling of distributed network services.
The financial landscape is rapidly evolving, presenting challenges for traditional systems. In response, the decentralised finance (DeFi) sector is emerging, driven by blockchain technology. This project, “DeFinance: Decentralised Lending and Borrowing of Digital Assets” aims to revolutionize financial services by providing an efficient, transparent, and inclusive lending and borrowing platform. Modules such as the dashboard, wallet connector, portfolio, markets, lending pool, and borrowing collectively offer users a comprehensive financial services platform. The key goals include trustless and transparent solutions, capital diversification, real-world asset tokenization, and seamless integration into the DeFi ecosystem. The project envisions a financial future marked by decentralization, inclusivity, and financial empowerment.
Jun 17, 2024·Proceedings of the 2024 Workshop on Advanced Tools, Programming Languages, and PLatforms for Implementing and Evaluating algorithms for Distributed systems
Reaching consensus despite faulty or corrupted nodes is a central question in distributed computing; it has received renewed attention over the last years because of its importance for cryptocurrencies and blockchain networks. Modern consensus protocols in this space have relied on a number of different methods for the nodes to influence protocol decisions. Such assumptions include (1) traditional voting, where each node has one vote, (2) weighted voting, where voting power is proportional to stake in an underlying asset, and (3) proof-of-X, which demonstrates a cryptographically verifiable investment of a resource X, such as storage space, time waited, or computational work.
Chris Natoli, Parinya Ekparinya, Guillaume Jourjon, Vincent Gramoli
Traditional blockchain systems offer a secure way of tracking the ownership of digital assets as long as the attacker does not control a large portion of the overall computational or mining power. They typically require participants to generate a proof-of-work before proposing a block at a given index of the chain. To choose one block among the candidate blocks at the same index, Nakamoto’s consensus, Ghost , and the original Ethereum’s consensus select, respectively, the longest branch, the heaviest subtree and the branch with the most difficult crypto-puzzles. This allows an attacker who can generate proofs-of-work faster than others to double spend by overwriting any given branch. In this article, we present a double spending attack, called the Balance attack, that simply needs to delay some messages. This result sheds new lights on an important, often implicit, assumption of the blockchain, synchrony , under which the transmission delay of any message should be within a known upper bound. We show that the attack succeeds with high probability on the protocols of the two largest blockchain systems in market capitalization, Bitcoin and Ethereum. To quantify the impact of our attack, we replicated the blockchain network run by 50 financial institutions and achieved double spending in less than 20 minutes. Finally, we demonstrate the success of the attack empirically by modifying the geth software and hijacking BGP in a controlled distributed system whose distribution of mining power is set to the distribution observed on the Ethereum main blockchain.
The last decade has witnessed unprecedented de-velopment in blockchain smart contracts. While smart contracts inherit the decentralization and other security properties of blockchain, they are hampered by the lack of privacy protection and poor performance of blockchain. In this paper, we propose a parallel contract execution framework, ParaEthereum, that combines blockchain and trusted execution environments (TEEs) to construct private, efficient, and scalable smart contracts. By introducing TEEs, ParaEthereum performs contract execution off the chain through enclave-enabled computing nodes and confirms the correctness of the execution results on the chain, achieving the decoupling of contract execution and consensus. To meet system availability requirements and enable concurrent exe-cution of transactions, each transaction is executed independently by a set of computing nodes determined by its execution set, and different computing nodes process transactions within the block concurrently based on the constructed transaction dependency graph. We also conducted extensive tests on our proposed scheme with respect to its efficiency and effectiveness.
Soosan Naderi Mighan, Jelena Mišić, Vojislav B. Mišić, Xiaolin Chang
Implementing a consensus protocol in a Proof-of-Stake context requires a delicate tradeoff between different system parameters. Ethereum 2.0, probably the most popular PoS system today, uses a large number of validators to achieve decentralization, but long time windows, during which both blocks and attestations for those blocks are considered valid, open up the possibility for a number of attacks that target the process of consensus. A possible remedy would be to try to achieve single-slot finality similar to that obtained in Practical Byzantine Fault Tolerance (PBFT). In this paper, we develop a Markov chain model of validator lifecycle in an Ethereum 2.0-like system with single-slot finality which includes penalties and rewards, as well as the possibility of voluntary exit and waiting to rejoin the validator pool. Using the model, we obtain the probability of achieving consensus as the function of probabilities of different events, most notably the probability of truthful voting by the validator. Our results indicate that consensus is rather sensitive to false voting, and that low probability of waiting and low probability of voluntary exit help improve the probability of consensus.
David Melo, Saúl E. Pomares Hernández, Lil María Rodríguez-Henríquez, Julio César Pérez-Sansalvador
Blockchain technology ensures record-keeping by redundantly storing and verifying transactions on a distributed network of nodes. Permissionless blockchains have pushed the development of decentralized applications (DApps) characterized by distributed business logic, resilience to centralized failures, and data immutability. However, storage scalability without sacrificing throughput is one of the remaining open challenges in permissionless blockchains. Enhancing throughput often compromises storage, as seen in projects such as Elastico, OmniLedger, and RapidChain. On the other hand, solutions seeking to save storage, such as CUB, Jidar, SASLedger, and SE-Chain, reduce the transactional throughput. To our knowledge, no analysis has been performed that relates storage growth to transactional throughput. In this article, we delve into the execution of the Bitcoin and Ethereum transactional models, unlocking patterns that represent any transaction on the blockchain. We reveal the trade-off between transactional throughput and storage. To achieve this, we introduce the spent-by relation, a new abstraction of the UTXO model that utilizes a directed acyclic graph (DAG) to reveal the patterns and allows for a graph with granular information. We then analyze the transactional patterns to identify the most storage-intensive ones and those that offer greater flexibility in the throughput/storage trade-off. Finally, we present an analytical study showing that the UTXO model is more storage-intensive than the account model but scales better in transactional throughput.
Today, blockchain ledgers utilize concurrent deterministic execution schemes to scale up. However, ordering fairness is not preserved in these schemes: although they ensure all replicas achieve the same serial order, this order does not always align with the fair, consensus-established order when executing smart contracts with runtime-determined accesses. To preserve ordering fairness, an intuitive method is to concurrently execute transactions and re-execute any order-violating ones. This in turn increases unforeseen conflicts, leading to scaling bottlenecks caused by numerous costly aborts under contention. To address these issues, we propose Spectrum, a novel deterministic execution scheme for smart contract execution on blockchain ledgers. Spectrum preserves the consensus-established serial order (so-called strict determinism) with high performance. Specifically, we leverage a speculative deterministic concurrency control to execute transactions in speculation and enforce an agreed-upon serial order by aborting and re-executing any mis-speculated ones. To overcome the scaling bottleneck, we present two key optimizations based on speculative processing: operation-level rollback and predictive scheduling, for reducing both the overhead and the number of mis-speculations. We evaluate Spectrum by executing EVM-based smart contracts on popular benchmarks, showing that it realizes fair smart contract execution by preserving ordering fairness and outperforms competitive schemes in contended workloads by 1.4x to 4.1x.
The rapid advancement of technology, alongside state-of-the-art techniques is at an all-time high. However, this unprecedented growth of technological prowess also brings forth potential threats, as oftentimes the security encompassing these technologies is imperfect. Particularly within the automobile industry, the recent strides in technology have brought about increased complexity. A notable flaw lies in the CAN-FD protocol, which lacks robust security measures, making it vulnerable to data theft, injection, replay, and flood data attacks. With the rising complexity of in-vehicular networks and the widespread adoption of CAN-FD, the imperative to safeguard the protocol has never been more crucial. This paper aims to provide a comprehensive review of the existing in-vehicle communication protocol, CAN-FD. It explores existing security approaches designed to fortify CAN-FD, demonstrating multiple multi-layer solutions that leverage modern techniques including Physical Unclonable Function (PUF), Elliptical Curve Cryptography (ECC), Ethereum Blockchain, and Smart contracts. The paper highlights existing multi-layer security measures that offer minimal overhead, optimal performance, and robust security. Moreover, it identifies areas where these security measures fall short and discusses ongoing research along with suggestions for implementing software and hardware-level modifications. These proposed changes aim to streamline complexity, reduce overhead while ensuring forward compatibility. In essence, the methods outlined in this study are poised to excel in real-world applications, offering robust protection for the evolving landscape of in-vehicular communication systems.
This paper introduces a novel incentivization scheme tailored for a leaderless Directed Acyclic Graph-based Distributed Ledger Technology. The distinctive feature of the proposed scheme lies in enabling a no-fee environment with a fixed supply token, all while incorporating a robust anti-spam mechanism and a well-defined incentivization scheme.
Mayank Raikwar, Nikita Polyanskii, Sebastian Müller
This paper is a Systematization of Knowledge (SoK) that focuses on Directed Acyclic Graph (DAG)-based consensus protocols in Distributed Ledger Technologies (DLTs). Our study evaluates their impact on performance and their tradeoffs concerning consistency, availability, and partition tolerance, as postulated by the CAP theorem. We delineate the key functionalities and tradeoffs of DAGbased consensus protocols, highlighting iterative improvements and deviations from foundational models. Additionally, we identify research gaps and suggest directions for future work to refine DAG-based consensus mechanisms.
David Guzman, Dirk Trossen, Trinh Viet Doan, Joerg Ott
In distributed consensus systems (DCSs), a single peer exposes functionality to other peers to agree on a shared state for a computational problem, such as for cryptocurrencies and distributed file systems. We observe, however, that this original, peer-centric model has evolved towards deploying several peers at a single network location, thus exposing the same DCS services many times, driven by the fees and rewards that can be gained by doing so. We refer to this trend as the service-centric model and provide in our paper evidence for this trend, its growth, and its impact on DCS operations, using empirical observations in the Ethereum system. Specifically, we shed light on the opposing observations of increasing reliance on highly available cloud infrastructures and large numbers of non-reachability events in the DCS. We provide recommendations on how to tackle this impact through changes to the Ethereum platform and identifier generation, believing that those recommendations and our empirical observations provide useful insights for building resilient and bias-free DePIN platforms.
Proof-of-Authority (PoA) is one of the popular blockchain consensus protocols, particularly for permissioned blockchains. However, PoA (as in Clique) still faces performance scalability issues. Its leader-based design restricts throughput and results in resource inefficiency, as it permits only one block to be accepted in each round, discarding all other concurrently proposed blocks in the same round. In this paper, we introduce DaPoA, an effort to enhance the Ethereum PoA Clique network to improve its performance scalability. The main idea of DaPoA is that it follows a parallel leader architecture that allows multiple sealers to propose their blocks in each round, which are then accepted in the same round. To achieve this, DaPoA employs a state-of-the-art directed acyclic graph (DAG)-based Byzantine Fault Tolerant (BFT) consensus algorithm, which enables parallel block proposals for high scalability with leader-less design. We have implemented and evaluated DaPoA on top of the Ethereum PoA Clique to demonstrate its performance scalability. In our setting of eight nodes, DaPoA achieves a 2.47 x higher throughput and 5.76x lower latency compared to Clique.
Srisht Fateh Singh, Panagiotis Michalopoulos, Andreas Veneris
This paper introduces BAKUP, a smart contract insurance design for decentralized finance users to mitigate risks arising from platform vulnerabilities. While providing automated claim payout, BAKUP utilizes a modular structure to harmonize three key features: the platform's resilience against vulnerabilities, the flexibility of underwritten policies, and capital efficiency. An immutable core module performs capital accounting while ensuring robustness against external vulnerabilities, a customizable oracle module enables the underwriting of novel policies, and an optional and peripheral yield module allows users to independently manage additional yield. The implementation incorporates binary conditional tokens that are tradable on automated market maker (AMM)-based exchanges. Finally, the paper examines specific liquidity provision strategies for the conditional tokens, demonstrating that a conservative strategy and parameterization can effectively reduce the divergence loss of liquidity providers by more than 47 % compared to a naive strategy in the worst-case scenario.
Distributed ledger technology such as blockchain is considered essential for supporting large numbers of micro-transactions in the Machine Economy, which is envisioned to involve billions of connected heterogeneous and decentralized cyber-physical systems. This stresses the need for performance and scalability of distributed ledger technologies. Addressing this, sharding techniques that divide the blockchain network into multiple committees are a common approach to improve scalability. However, with current sharding approaches, costly cross-shard verification is needed to prevent double-spending. This article proposes a novel and more scalable distributed ledger method named ScaleGraph that implements dynamic sharding by using routing and logical proximity concepts from distributed hash tables. ScaleGraph addresses cybersecurity in terms of integrity and availability to support frequent micro-transactions between autonomous devices. Benefits of ScaleGraph include a total storage space complexity of \(O(t)\) , where \( t \) is the global number of transactions (assuming a constant replication degree). This space is sharded over \( N \) nodes so that each node needs \(O(t/N)\) storage in expectation, which provides a high level of concurrency and data localization as compared to other delegated consensus proposals. ScaleGraph allows for a dynamic grouping of validators that are selected based on a distance metric. We analyze the consensus requirements in such a dynamic setting and show that a synchronous consensus protocol allows shards to be smaller than an asynchronous one, and likely yields better performance. Moreover, we provide an experimental analysis of security aspects regarding the required size of the consensus groups with ScaleGraph. Our analysis shows that dynamic sharding based on proximity concepts brings attractive scalability properties in general, especially when the fraction of corrupt nodes is small.
Shan Wang, Ming Yang, Wenxuan Dai, Yu Liu · 6 authors
Third-party RPC services have become the mainstream way for users to access Ethereum. In this paper, we present a novel deanonymization attack that can link an Ethereum address to a real-world identity such as IP address of a user who accesses Ethereum via a third-party RPC service. We find that RPC API calls result in distinguishable sizes of encrypted TCP packets. An attacker can then find when a user sends a transaction to an RPC provider and immediately send a beacon transaction after the user transaction. By exploiting the differences in the distributions of inter-arrival time intervals of normal transactions and two simultaneously initiated transactions, the attacker can identify the victim transaction in the Ethereum network. This enables the attacker to correlate the Ethereum address of the victim transaction’s initiator with the source IP address of TCP packets from a victim user. We model the attack through empirical measurements and conduct extensive real-world experiments to validate the effectiveness of our attack. With three optimization strategies, the correlation accuracy can reach to 98.70% and 96.60% respectively in Ethereum testnet and mainnet. We are the first to study the deanonymization of Ethereum users behind third-party RPC services.
Miguel Isabel, Clara Rodríguez-Núñez, Albert Rubio
The application of Zero-Knowledge (ZK) proofs is rapidly growing in the industry and has become a key element to enable privacy and enhance scalability in public distributed ledgers. In most practical ZK systems, the statement to be proven is expressed by means of a set of polynomial equations in a prime field that describe an arithmetic circuit. Describing general statements using this kind of constraints is a complex and error-prone task. This can be partly mitigated by using high-level programming languages, but at the cost of losing control over the added constraints and, as a result, obtaining too large systems for complex statements. In this context, having tools to automatically verify properties of the constraint systems is of paramount importance to guarantee the security of the protocol. However, since non-linear polynomial reasoning over a finite field is needed for checking challenging properties, existing automatic tools either do not scale or cannot detect non-trivial bugs. In this paper, we present a new scalable modular technique based on the application of transformation and deduction rules that have proven to be very effective in verifying properties over the signals of a circuit given as a set of polynomial equations in a large prime field. Our technique has been implemented in a tool called CIVER and applied to verify safety properties for circuits implemented in circom, which is one of the most popular languages for defining ZK protocols. We have been able to analyze large industrial circuits and detect subtle vulnerabilities in circuits designed by expert programmers.