SNARKChain Proof-of-Useful-Work Blockchain Consensus with General-Purpose SNARK Marketplace

Jul 16, 2026

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Proof of Work secures permissionless blockchains but wastes electricity on computationally intensive yet externally useless puzzles. Proof of Useful Work (PoUW) aims to produce real-world value while maintaining security; however, many proposals fail to bind chain integrity and miner identity into puzzle solutions, leaving gaps against PoW-like requirements. SNARKChain introduces a PoUW consensus where client-outourced SNARK proofs are computed as the useful work, then reused to secure consensus. It further enables a decentralized marketplace for general-purpose SNARK proof generation operating at the consensus layer.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages12

Reading Time30 min

Introduction

Background

SNARKChain: Proof-of-Useful-Work Blockchain Consensus with General-Purpose SNARK Marketplace Samuel Oleksak, Richard Gazdik, Martin Pere´ıni, Ivan Homoliak Brno University of Technology Faculty of Information Technology Brno, Czechia arXiv :2510 .09729v2 [ cs .CR] 13 Jul 2026 Abstract—Proof of Work (PoW) is widely regarded as the most secure permissionless blockchain consensus protocol. However, its reliance on computationally intensive yet externally useless puzzles results in excessive electric energy wasting. To alleviate this, Proof of Useful Work (PoUW) has been explored as an alternative to secure blockchain platforms while also producing real-world value. Despite this promise, existing PoUW proposals often fail to embed the integrity of the chain and the identity of the miner into the puzzle solutions, not meeting the necessary requirements for PoW and thus rendering them vulnerable. In this work, we propose a PoUW consensus protocol that computes client-outsourced SNARK proofs as a byproduct, which are simultaneously used to secure the consensus protocol. We further leverage this mechanism to design a decentralized marketplace for outsourcing SNARK proof generation, which is, to the best of our knowledge, the first such marketplace operating at the consensus layer while meeting all necessary properties of PoW. I. INTRODUCTION Permissionless blockchain systems rely on consensus protocols to provide agreement among mutually distrusting nodes. The first and still one of the most popular blockchain consensus protocols is Proof of Work (PoW) [1] . PoW secures the network from Sybil attacks by requiring the nodes that participate in consensus to solve computationally intensive puzzles, such as finding a particular hash [1], solving memoryhard problems [2], or completing randomized computational tasks [3] . The results of these puzzles typically do not have any use outside the consensus protocol, which leads to this protocol being labeled as wasteful and environmentally harmful. Some reports [4] suggest that Bitcoin alone may be responsible for 65.4 megatonnes of CO2 emitted per year, which is comparable to the country-level emissions of Greece. To justify the energy consumption of PoW, the community has proposed puzzles that deliver value beyond securing the consensus protocol, with notable examples including Cunningham chains [3], Cuckoo cycles [5], DNA sequence alignment [6], and deep learning model training [7] . Protocols incorporating such useful computational puzzles are known as Proof of Useful Work (PoUW) protocols. These protocols have not yet gained significant traction in the blockchain space, mainly due to the challenges in designing meaningful tasks that meet the core PoW requirements, such as the verifiability of solutions, adjustable hardness, solution replay attack resistance (freshness), and chain integrity embedding [8], [9] . Zero-knowledge Succinct Non-interactive Arguments of Knowledge (zk-SNARKs) [10] are a powerful cryptographic tool that enables verifiable computation and privacy preservation by allowing a prover to convince a verifier of the truth of a statement with no interaction and without revealing the underlying data. However, their usability is hindered by the fact that generating zk-SNARKs is both computationally and memory intensive, often requiring tens of gigabytes of RAM and taking tens of minutes even on high-end hardware, making them impractical to compute on resource-constrained devices. To address this, various off-chain proof generation frameworksand marketplaces have been proposed, allowing users to delegate proof generation to external providers. These solutions can be broadly grouped as (a) centralized [11] and decentralized [12], [13], depending on whether a trusted operator manages task allocation and payments or whether matching is achieved through a peer-to-peer protocol, and (b) those that operate at the application layer [14], where proof outsourcing

FAQs

What problem does SNARKChain address compared with Proof of Work?

Proof of Work relies on puzzles that consume significant electricity while providing no value beyond consensus security. SNARKChain replaces that wasteful work with useful computation that also strengthens consensus.

How does SNARKChain incorporate useful work into consensus security?

The protocol computes client-outourced zk-SNARK proofs as the useful work. These proofs are simultaneously used to secure the consensus process.

What is the role of the decentralized SNARK marketplace in the system?

SNARKChain leverages the proof-byproduct mechanism to support decentralized outsourcing of general-purpose zk-SNARK generation, designed to operate at the consensus layer with PoW-level properties.

Jul 16, 2026

Upload by Patrick