Light Client Research Articles

Techniques to alleviate blockchain bloat: Potentials, challenges, and recommendations

Blockchain (BC) bloat, characterized by excessive data growth on BC networks, presents a pressing challenge. The need for a comprehensive study addressing BC bloat solutions arises due to the scarcity of knowledge in this emerging area. This study advances knowledge along with practical insights and inspires innovative approaches to address BC bloat. This research explores various techniques proposed to combat BC bloat. Two technique themes are identified: on-chain and off-chain techniques. On-chain techniques focus on updating the consensus mechanism, block size, or database partition. This study identified five on-chain techniques: structural modification, pruning, sharding, ephemeral BC, and zk-SNARKs. Off-chain techniques focus on processing in parallel, bundling transactions, or handling transactions off-chain. Further, three off-chain techniques identified are off-chain storage, historical data storage, and light clients’ techniques. These recommendations aim to optimize resources use, enhance scalability, and maintain data integrity. However, these may compromise several BC capabilities, such as security, privacy, and data loss. The applicability of these techniques for resource-constrained devices is also explored. Future research should include further investigation into the performance and applicability of these techniques, especially in resource-constrained environments like IoT and fog computing.

Faster Montgomery multiplication and Multi-Scalar-Multiplication for SNARKs

The bottleneck in the proving algorithm of most of elliptic-curve-based SNARK proof systems is the Multi-Scalar-Multiplication (MSM) algorithm. In this paper we give an overview of a variant of the Pippenger MSM algorithm together with a set of optimizations tailored for curves that admit a twisted Edwards form. We prove that this is the case for SNARK-friendly chains and cycles of elliptic curves, which are useful for recursive constructions. Our contribution is twofold: first, we optimize the arithmetic of finite fields by improving on the well-known Coarsely Integrated Operand Scanning (CIOS) modular multiplication. This is a contribution of independent interest that applies to many different contexts. Second, we propose a new coordinate system for twisted Edwards curves tailored for the Pippenger MSM algorithm.Accelerating the MSM over these curves is critical for deployment of recursive proof< systems applications such as proof-carrying-data, blockchain rollups and blockchain light clients. We implement our work in Go and benchmark it on two different CPU architectures (x86 and arm64). We show that our implementation achieves a 40-47% speedup over the state-of-the-art implementation (which was implemented in Rust). This MSM implementation won the first place in the ZPrize competition in the open division “Accelerating MSM on Mobile” and will be deployed in two real-world applications: Linea zkEVM by ConsenSys and probably Celo network.

Toward a Secure, Rich, and Fair Query Service for Light Clients on Public Blockchains

The rapid growth of storage overhead on public blockchains has urged the use of light clients that only store a small fraction of blockchain data and rely on other bootstrapped full nodes for data retrievals. Unfortunately, current blockchain light client designs are far from satisfactory. First, outsourcing retrieval requests could raise severe concerns about result correctness and privacy threats. Second, current light clients do not support rich query and enforce fee payments to full nodes. Given that blockchain storage increases day by day, enabling effective rich blockchain queries and fairly compensating full nodes’ ever growing costs has become extremely necessary. In this article, we propose a general and secure paid query framework to simultaneously meet those demands above. Specifically, we leverage the integration of trusted hardware (e.g., Intel SGX) and smart contract as a starting point for building efficient yet secure query processing with fair payments. Then, we further craft several crucial performance and security refinement designs to boost query efficiency and enforce result correctness, and also explore an enclave-facilitated fair settlement mechanism for on-chain cost optimizations. We implement a prototype of our paid query framework and the experimental result has demonstrated its practically affordable cost.

Aurora-Trinity: A Super-Light Client for Distributed Ledger Networks Extending the Ethereum Trinity Client.

Light clients for distributed ledger networks can verify blockchain integrity by downloading and analyzing blockchain headers. They are designed to circumvent the high resource requirements, i.e., the large bandwidth and memory requirements that full nodes must meet, which are unsuitable for consumer-grade hardware and resource-constrained devices. Light clients rely on full nodes and trust them implicitly. This leaves them vulnerable to various types of attacks, ranging from accepting maliciously forged data to Eclipse attacks. We introduce Aurora-Trinity, a novel version of light clients that addresses the above-mentioned vulnerability by relying on our original Aurora module, which extends the Ethereum Trinity client. The Aurora module efficiently discovers the presence of malicious or Byzantine nodes in distributed ledger networks with a predefined and acceptable error rate and identifies at least one honest node for persistent or ephemeral communication. The identified honest node is used to detect the latest canonical chain head or to infer the state of an entry in the ledger without downloading the header chain, making the Aurora-Trinity client extremely efficient. It can run on consumer-grade hardware and resource-constrained devices, as the Aurora module consumes about 0.31 MB of RAM and 1 MB of storage at runtime.

Transparent subsidized agri‐product distribution during pandemics with reputation based PoA blockchain

SummaryTechnological advancements play a crucial role in agriculture sector aiming at eradicating numerous problems. These problems are intensified due to pandemics like delay overhead in the subsidized agri‐products supply chains. The existing technology‐based solutions are not readily adopted by stakeholders due to absence of trust. Blockchain can impart more transparency and trust in agri‐supply chains leading to fair pricing. The idea of using blockchain for financing processes in agriculture has resulted from the managerial pressure and fiscal scams which eventually aggravate the plight of farmers. Thus, a blockchain‐based subsidized agri‐products distribution (SAPD) is proposed. Blockchain has been optimized by a reputation‐based Proof‐of‐Authority (PoA) consensus algorithm. It has been implemented using Ethereum blockchain on AWS EC2 cloud. The smart contract is designed in solidity. Detailed performance evaluation has been conducted to compute cost and processing time that shows a substantial reduction in cost of managerial operations with respect to previous work by 41.65%. Finally, to assess the utility of SAPD system a qualitative user survey has been conducted. Managerial significance of system is reflected in memory space reduction by 85% in light clients and increase in transaction execution per second by 31% using reputation‐based PoA.

Time-Dilation Attacks on the Lightning Network

Lightning Network (LN) is a widely-used network of payment channels enabling faster and cheaper Bitcoin transactions. In this paper, we outline three ways an attacker can steal funds from honest LN users. The attacks require dilating the time for victims to become aware of new blocks by eclipsing (isolating) victims from the network and delaying block delivery. While our focus is on the LN, time-dilation attacks may be relevant to any second-layer protocol that relies on a timely reaction. According to our measurements, it is currently possible to steal the total channel capacity by keeping a node eclipsed for as little as 2 hours. Since trust-minimized Bitcoin light clients currently connect to a very limited number of random nodes, running just 500 Sybil nodes allows an attacker to Eclipse 47\% of newly deployed light clients (and hence prime them for an attack). As for the victims running a full node, since they are often used by large hubs or service providers, an attacker may justify the higher Eclipse attack cost by stealing all their available liquidity. In addition, time-dilation attacks neither require access to hashrate nor purchasing from a victim. Thus, this class of attacks is a more practical way of stealing funds via Eclipse attacks than previously anticipated double-spending. We argue that simple detection techniques based on the slow block arrival alone are not effective, and implementing more sophisticated detection is not trivial. We suggest that a combination of anti-Eclipse/anti-Sybil measures are crucial for mitigating time-dilation attacks.

LOPE: A Low‐Overhead Payment Verification Method for Blockchains

With its characteristics of decentralization, security, data traceability, and tamper-resistance, the blockchain has been widely used in various domains. Considering the difference in the performance of the devices, the light client is proposed so that devices without the ability to store a full blockchain copy can also participate in the blockchain transactions. However, the light client has to communicate with full nodes and verify the authenticity of a transaction which brings in some extent of communication, computation, and storage overheads to the light client. These overheads cannot be ignored for some low-performance devices, such as embedded devices or IoT chips, and therefore the current light client scheme does not work in this situation. We propose LOPE (a Low-overhead payment vErification method) for poor-capacity nodes in the blockchain system. In LOPE, a grouping protocol is designed to partition full nodes into groups to serve the verification requests of the light client. In addition, Practical byzantine fault tolerance (PBFT) is used to ensure the light client to get a credible result in spite of a few dishonest nodes existing in the group. We conduct LOPE and evaluate it in a testbed. The experiment results show that LOPE reduces more than half of the communication overhead, degrades the computation overhead of the light client to a large extent, and avoids the storage overhead of the hash roots of block headers in the light client. We also conduct theoretical analysis to show the performance improvement and security issues of LOPE.

T-CREo: A Twitter Credibility Analysis Framework

Social media and other platforms on Internet are commonly used to communicate and generate information. In many cases, this information is not validated, which makes it difficult to use and analyze. Although there exist studies focused on information validation, most of them are limited to specific scenarios. Thus, a more general and flexible architecture is needed, that can be adapted to user/developer requirements and be independent of the social media platform. We propose a framework to automatically and in real-time perform credibility analysis of posts on social media, based on three levels of credibility: Text , User , and Social . The general architecture of our framework is composed of a front-end, a light client proposed as a web plug-in for any browser; a back-end that implements the logic of the credibility model; and a third-party services module. We develop a first version of the proposed system, called T-CREo ( T witter CRE dibility analysis framew o rk) and evaluate its performance and scalability. In summary, the main contributions of this work are: the general framework design; a credibility model adaptable to various social networks, integrated into the framework; and T-CREo as a proof of concept that demonstrates the framework applicability and allows evaluating its performance for unstructured information sources; results show that T-CREo qualifies as a highly scalable real-time service. The future work includes the improvement of T-CREo implementation, to provide a robust architecture for the development of third-party applications, as well as the extension of the credibility model for considering bots detection, semantic analysis and multimedia analysis.

Security Properties of Light Clients on the Ethereum Blockchain

Ethereum is a decentralized blockchain, known as being the second most popular public blockchain after Bitcoin. Since Ethereum is decentralised the canonical state is determined by the Ethereum network participants via a consensus mechanism without a centralized coordinator. The network participants are required to evaluate every transaction starting from the genesis block, which requires a large amount of network, computing, and storage resources. This is impractical for many devices with either limited computing resources or intermittent network connectivity. To overcome this drawback Ethereum defines a light client protocol where the light client fetches the blockchain state from a node operating as a light protocol server. Light clients are unable to maintain blockchain state internally, and as a consequence can only perform partial validation on blocks. Thus they rely on the light server for full block validation and to provide the updated blockchain state. Light clients connect to multiple light servers to mitigate the risk of relying on a single potentially dishonest server. Ethereum light clients are known to suffer from a probabilistic security model, but they are widely assumed to be secure under normal operating conditions. In fact, the implicit security assumptions of light clients have not been formally characterised in the literature. We present and analyse the probabilistic security guarantees under three different adversarial scenarios. The results show that for any adversary that is able to manipulate the network, the security assurances provided by the light protocol are severely impacted, and in some cases entirely lost. These results clearly demonstrate that the assumption of normal operating conditions is insufficient to justify the security assumptions of light clients. Our work also provides insight to the security of light clients under different security parameters, allowing light client implementers to more accurately understand the potential security trade-offs.

Remote access protocols for Desktop-as-a-Service solutions.

The use of remote desktop services on virtualized machines is a general trend to reduce the cost of desktop seats. Instead of assigning a physical machine with its operating system and software to each user, it is considerably easier to manage a light client machine that connects to a server where the instance of the user’s desktop machine actually executes. Citrix and VMware have been major suppliers of these systems in private clouds. Desktop-as-a-Service solutions such as Amazon WorkSpaces offer a similar functionality, yet in a public cloud environment. In this paper, we review the main offerings of remote desktop protocols for a cloud deployment. We evaluate the necessary network resources using a traffic model based on self-similar processes. We also evaluate the quality of experience perceived by the user, in terms of image quality and interactivity, providing values of Mean Opinion Score (MOS). The results confirm that the type of application running on the remote servers and the mix of users must be considered to determine the bandwidth requirements. Applications such as web browsing result in unexpectedly high traffic rates and long bursts, more than the case of desktop video playing, because the on-page animations are rendered on the server.

Securing light clients in blockchain with DLCP

SummaryIn blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions. In contrast, light clients (LCs) are those with limited resources, and for this reason, they request only block headers from FNs for transaction verification—using protocols like Simple Payment Verification (SPV). In an approach to prevent FN tampering on transaction verification (byzantine fault), LCs request block headers from multiple FNs and compare received responses. One problem with this approach is that an LC must connect to each FN and perform the same cryptographic operations with each one repeatedly, which leads to client‐side complexity and slower response. We propose an alternate approach to tackle this issue, in which LCs can encrypt a request for block headers only once, and send that request to a predetermined set of FNs to access, process, and reply back in a single response. Our approach, called Distributed Lightweight Client Protocol (DLCP), enables LCs to verify with little effort if FNs have agreed on a response. From an experimental evaluation, we observed that DLCP provided lower latency and reduced computing and communication overhead in comparison with the existing conventional approach.

A software architecture for virtualized educational multimedia games in IPTV environments

SUMMARYT‐Learning makes it possible to deliver educational content to home TVs. TV operators, which manage huge populations of devices such as set‐top‐boxes (STBs) in user homes, are considering t‐Learning as an interesting option for expanding the service they offer. However, typical STB hardware configurations are limited in terms of satisfying operator needs and do not easily support all types of applications or content. In this work, we consider graphic < e‐Adventure > educational games, which are not directly executable on typical STBs. To cover this gap and guarantee an enjoyable user experience, we present an architecture based on a combination of streaming and remote desktop protocols that relies on virtualized servers deployed in a cloud computing infrastructure. It features an original image‐encoding signalling mechanism that identifies multimedia content in educational games and permits seamless protocol switching at the client side. This architecture is a complete technological solution to virtualize heavy educational games and execute them smoothly on STB light clients over Internet Protocol Television networks. We present performance results that show that our proposal is an efficient scalable solution to deliver t‐Learning to home environments. Copyright © 2013 John Wiley & Sons, Ltd.

A real-time simulation grid for collaborative virtual assembly of complex products

Simulation of collaborative virtual assembly (CVA) processes is a helpful tool for product development. However, existing collaborative virtual assembly environments (CVAE) have many disadvantages with regard to computing capability, data security, stability, and scalability, and moreover it is difficult to create enterprise applications in these environments. To support large-scale CVAEs offering high fidelity and satisfactory interactive performance among various distributed clients, highly effective system architectures are needed. In this paper, a collaborative virtual assembly scheme based on grid technology is proposed. This scheme consists of two parts: one is a grid-based virtual assembly server (GVAS) which can support parallel computing, the other a set of light clients which can support real-time interaction. The complex and demanding computations required for simulation of virtual assembly (VA) operations, such as model rendering, image processing (fusion), and collision detection, are handled by the GVAS using network resources. Users at the light clients input operation commands that are transferred to the GVAS and receive the results of these operations (images or video streams) from the GVAS. Product data are managed independently by the GVAS using the concept of RBAC (role-based access control), which is secure enough for this application. The key related technologies are discussed, and a prototype system is developed based on the web services and VA components identified in the paper. A case study involving a car-assembly workstation simulation has been used to verify the scheme.

The Role of Fusion Hybrids for Fissile Fuel Production in Future Power Generation Systems

The use of the fusion hybrid to supply fissile fuel for conventional light water client reactors beginning at the turn of the century is discussed. Utility needs for the hybrid are formulated by generation expansion analyses while the ability of various hybrid concepts to meet these needs are forecast based on computer models of hybrid cost and performance characteristics. It is concluded that the fusion hybrid is an economically attractive option which has the potential to establish a ceiling on nuclear fuel price increases in the first or second decade of the twenty-first century.