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.
“The only practical solution is to set a hard deadline for account owners to migrate their tokens to quantum safe accounts, after which all tokens held in vulnerable accounts will be permanently frozen,” said Auryn Macmillan, co-founder of Gnosis Guild.
That possibility would represent one of the most controversial governance interventions in crypto history, potentially forcing users to migrate assets under protocol-imposed timelines rather than voluntary adoption.
Hardware Wallets And Exchanges Face Operational Challenges
The report describes the coming transition as the “Great Quantum Filter,” a period where capital could begin moving from quantum-vulnerable blockchains toward chains designed with post-quantum cryptography from inception.
Hardware limitations may further complicate the process.
“For a hardware wallet, the device is typically MCU-based, which means its hardware resources are inherently limited,” said Aaron Chen, CTO of Keystone. “For algorithms such as ML-DSA-87, the hardware resource requirements are significantly higher, particularly when user experience must also be preserved.”
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The report notes that many blockchain systems still rely on elliptic-curve cryptography schemes such as ECDSA and Ed25519, both of which are theoretically vulnerable to Shor’s algorithm once sufficiently advanced quantum systems emerge. Public keys already exposed onchain remain permanently visible, creating a lasting attack surface for older wallets and reused addresses.
Unlike traditional internet infrastructure, which can often rotate cryptographic systems through centralized software updates, blockchains face a more difficult path because assets are user-controlled, governance is decentralized, and dormant wallets may remain exposed indefinitely.
Quantum Timelines Are Compressing Faster Than Expected
While the industry has often treated quantum risk as distant, some researchers argue the timeline is compressing faster than expected.
“All we did was take the published performance specs over time of commercially available quantum computers and draw them on a line of best fit for exponential growth,” said Colton Dillion, CEO of Quip Networks. “We stand by this forecast as a quantitative guide for making decisions about quantum risk.”
Matt Swayne, Chief Content Officer at Resonance, warned that the industry may still be underestimating the pace of development.
“We often hear about quantum hype, but we also have to be aware that the quantum industry is underselling its progress,” Swayne said. “Companies and organizations, particularly in the crypto industry, should be aware of the landscape and options to mitigate any potential threat.”
Stablecoins, Bridges And DeFi Infrastructure Could Also Be Exposed
The report warns that the risk extends beyond retail wallets. Stablecoin administrator keys, multisig custody systems, bridge validators, oracle networks, and governance contracts all depend on classical cryptography today. A compromise at those layers could affect lending markets, cross-chain liquidity, derivatives infrastructure, automated market makers, and institutional custody flows simultaneously.
NIST finalized its first post-quantum standards in 2024, and companies including Signal, Chrome, and Apple’s iMessage have already begun integrating them into production systems. Crypto infrastructure providers, however, remain in much earlier stages of adoption.
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