On Scaling LT-Coded Blockchains in Heterogeneous Networks and their Vulnerabilities to DoS Threats

TL;DR

This paper addresses scaling LT-coded blockchains in heterogeneous networks by introducing two hybrid decoders, BRH and CRH, that optimize the trade-off between bootstrap overhead and computational complexity via a mirroring-cost framework. It provides analytical and simulation-based assessments showing these decoders can achieve lower mirroring costs than traditional BP/OFG decoders, enabling more efficient blockchain mirroring under diverse node capabilities. The work also uncovers vulnerabilities to non-oblivious DoS attacks, designing attacker strategies that leverage decoder structure to deny new nodes decoding capability, and offers cost-constrained attack analyses to guide defense priorities. Together, these contributions advance perspectives on secure, scalable coded-blockchain designs that balance storage savings, decoding efficiency, and resilience to optimized threats. The findings have practical implications for deploying LT-coded blockchains in real networks where heterogeneity and adversarial activity shape performance and security.

Abstract

Coded blockchains have acquired prominence as a promising solution to reduce storage costs and facilitate scalability. Within this class, Luby Transform (LT) coded blockchains are an appealing choice for scalability owing to the availability of a wide range of low-complexity decoders. In the first part of this work, we identify that traditional LT decoders like Belief Propagation and On-the-Fly Gaussian Elimination may not be optimal for heterogeneous networks with nodes that have varying computational and download capabilities. To address this, we introduce a family of hybrid decoders for LT codes and propose optimal operating regimes for them to recover the blockchain at the lowest decoding cost. While LT coded blockchain architecture has been studied from the aspects of storage savings and scalability, not much is known in terms of its security vulnerabilities. Pointing at this research gap, in the second part, we present novel denial-of-service threats on LT coded blockchains that target nodes with specific decoding capabilities, preventing them from joining the network. Our proposed threats are non-oblivious in nature, wherein adversaries gain access to the archived blocks, and choose to execute their attack on a subset of them based on underlying coding scheme. We show that our optimized threats can achieve the same level of damage as that of blind attacks, however, with limited amount of resources. Overall, this is the first work of its kind that opens up new questions on designing coded blockchains to jointly provide storage savings, scalability and also resilience to optimized threats.

Figures (18)

• Figure 1: Number of contributions that implement RS, Fountain, LDPC and LCC codes to address scalability issues in blockchains (source: Survey paper).
• Figure 2: Depiction of coded blockchain architecture wherein $k$ blocks of an epoch are coded to generate $S$ coded blocks and then stored across $S$ droplet nodes. The vectors $\mathbf{v}$ store the indices of the message blocks used to generate the corresponding coded block, thus capturing the degree information. The most recent $\tau$ blocks are stored in an uncoded format to handle blockchain reorganizations due to potential forks SeF.
• Figure 3: Depiction of generating a coded droplet from an epoch using LT encoding.
• Figure 4: Illustration of bipartite graph $\mathcal{T}$ formed using the coded droplets collected by a bucket node.
• Figure 5: BRH and CRH decoders acting as bridge between BP and OFG in terms of bootstrap overhead vs computational complexity trade-off.

Theorems & Definitions (19)

• Definition 1: Bootstrap overhead
• Definition 2: Computational complexity
• Proposition 1
• proof
• Proposition 2
• proof
• Theorem 1
• proof
• Theorem 2
• proof