The Cost of Quantum Resistance: A Hash-Based Commit-Reveal Alternative for Minimizing Blockchain Infrastructure Overhead

2026-05-07

AI Summary

This work addresses the challenges of transaction bloat and significantly increased node verification overhead that arise when migrating blockchain systems to post-quantum cryptography. The authors propose a hash-based commit-reveal mechanism that restructures transaction semantics—rather than directly substituting signature schemes—by splitting each signed transaction into two lightweight transactions containing only 32-byte hash values. Under standard hash function assumptions, this approach achieves post-quantum security while introducing merely 1.5–2× data overhead, substantially lower than existing post-quantum signature schemes. Consequently, it effectively mitigates network-wide data amplification and offers an efficient, practical migration pathway for large-scale blockchain systems.

Abstract

The transition to post-quantum cryptography in blockchain systems such as Bitcoin and Ethereum is often framed as a purely cryptographic problem. In practice, it also presents significant economic and infrastructural challenges: in globally replicated networks, increases in transaction size and verification cost are multiplied across all participating nodes. Existing post-quantum signature schemes, including lattice-based constructions such as CRYSTALS-Dilithium and stateless hash-based schemes such as SPHINCS+, introduce substantial increases in signature size. At blockchain scale, these increases translate into higher storage, bandwidth, and validation requirements, potentially requiring multiple generations of hardware improvement to become operationally routine. Historical experience suggests that even moderate increases in data footprint can be contentious, as illustrated by the Bitcoin block size debates (2015--2017). We propose a hash-based commit--reveal construction that replaces a single signature-bearing transaction with two lightweight transactions, each containing a fixed-size (32-byte) hash output derived from well-established primitives such as SHA-256, BLAKE, or Keccak. This approach achieves post-quantum security under standard hash assumptions while increasing the effective transaction footprint by only approximately 1.5$\times$ to 2$\times$ per authorization event. These results indicate that practical post-quantum migration may benefit from rethinking transaction semantics rather than directly adopting larger signature schemes, and that viable designs for decentralized systems must account for system-wide cost amplification.

Problem

• post-quantum cryptography
• blockchain
• transaction size
• infrastructure overhead
• signature schemes

Innovation

• post-quantum cryptography
• hash-based commit-reveal
• blockchain scalability
• transaction overhead
• lightweight authentication