The Great Quantum Filter Is Coming And It Could Freeze Your Crypto

The crypto industry’s transition to a post-quantum future may create a scalability and governance crisis far larger than the industry currently acknowledges, according to a new report from quantum-secure blockchain project Quantus, which argues that Bitcoin (BTC) and other legacy chains could struggle to migrate before quantum hardware reaches dangerous capability thresholds.

The report warns that the industry’s biggest problem is no longer simply whether quantum computers will eventually break classical cryptography. Instead, the challenge is whether decentralized networks can realistically coordinate a migration to post-quantum systems without overwhelming scalability limits, wallet infrastructure, and governance processes.

Bitcoin’s Post-Quantum Upgrade Could Break Scalability Assumptions

Quantus estimates the burden could become severe for Bitcoin specifically. A standard Bitcoin transaction using ECDSA signatures carries roughly 97 bytes of signature and public key data. A comparable transaction using ML-DSA-87, one of the post-quantum signature standards finalized by NIST in 2024, would carry approximately 7,187 bytes, representing a roughly 74-fold increase.

That increase would sharply reduce transaction capacity per block unless Bitcoin undergoes deeper architectural changes beyond a simple cryptographic swap. The report argues that larger signatures, privacy requirements, and scalability constraints are creating a new version of the blockchain trilemma for the post-quantum era.