SPID-Chain: A Smart Contract-Enabled, Polar-Coded Interoperable DAG Chain

TL;DR

SPID-Chain tackles blockchain interoperability in Web3 by introducing a dual-layer consensus: intra-consensus within each chain using Event-Driven Smart Contracts (EDSC) and coded distributed computing with Polar codes, and inter-consensus across chains via a DAG ledger. Cross-chain blocks Z_j^P(t) are proposed per epoch and validated through a DAG-based aggregation with weight-based finality, while intra-chain processing leverages six smart contracts to trigger event-driven tasks and coordinate committee/worker actions. The system uses VRF-based committee selection, stake-derived weights ω_j (with ∑_j ω_j = 1), and an aggregated DAG weight AW to determine block confirmations, enhancing scalability, security, and decentralization. Simulations on a Substrate-GoShimmer setup demonstrate strong intra- and inter-consensus throughput (up to ~11 blocks/min), improved decentralization with larger K, and robust resistance to double-spend and adversarial spamming, highlighting SPID-Chain’s potential for seamless cross-chain interactions in Web3 networks.

Abstract

As the digital landscape evolves, Web3 has gained prominence, highlighting the critical role of decentralized, interconnected, and verifiable digital ecosystems. This paper introduces SPID-Chain, a novel interoperability consensus designed for Web3, which employs a directed acyclic graph (DAG) of blockchains to facilitate seamless integration across multiple blockchains. Within SPID-Chain, each blockchain maintains its own consensus and processes transactions via an intra-consensus mechanism that incorporates event-driven smart contracts (EDSC) and Polar codes for optimized computation distribution. This mechanism is complemented by a division of committee and worker nodes, enhancing transaction processing efficiency within individual chains. For inter-blockchain consensus, SPID-Chain utilizes a DAG structure where blockchains append blocks containing cross-chain transactions. These blocks are then processed through the inter-consensus mechanism orchestrated by the blockchains. Extensive simulations validate the efficacy of our scheme in terms of throughput, scalability, decentralization, and security. Our results showcase SPID-Chain's potential to enable fluid interactions and transactions across diverse blockchain networks, aligning with the foundational goals of Web3.

Figures (8)

• Figure 1: Evolution of a DAG ledger over two consecutive epochs. Nodes are color-coded to indicate their status: yellow for unconfirmed, green for confirmed, and red for tips. The blue text represents the AW associated with each node.
• Figure 2: Intra-consensus throughput with $N=10$, $n=100$, and for varying straggler worker percentages $\lambda$ and incoming block rates.
• Figure 3: Intra-consensus scalability with $\lambda=10\%$, $12$ blocks per minute for rate of incoming blocks, and for varying numbers of nodes within each blockchain and different numbers of blockchains $N$.
• Figure 4: Inter-consensus throughput with $\lambda=10\%$, $N=10$, $K=2$, $\mu_{\text{crit}}=50\%$, and for varying rates of incoming blocks and spamming rates.
• Figure 5: Inter-consensus scalability for varying numbers of blockchains $N$ and worker nodes within each blockchain $n\in\{100,\,200\}$ with fixed incoming block rate $10$ blocks per min, $\mu=20\%$, $\lambda=10\%$, $K=2$, and $\mu_{\text{crit}}=50\%$.