Project Eleven’s 2026 “Quantum Threat to Blockchains” report projects that “Q‑Day” — the point when quantum computers can break today’s public‑key encryption — is most likely to arrive around 2033, with plausible outcomes between 2030 and 2042.
The report introduces a quantitative model to track progress toward a cryptographically relevant quantum computer (CRQC), assesses how quickly quantum capability is improving, and maps those advances to specific vulnerabilities across blockchain ecosystems. It also lays out technical migration paths for organizations aiming to harden their systems against future quantum attacks.
Key findings and timeline
- Baseline Q‑Day estimate: ~2033
- Early arrival window: as soon as 2030
- Late arrival window: up to 2042
- Primary concern: ability to break widely used schemes such as RSA‑2048 and elliptic curve cryptography (ECC), including those used in major digital asset networks.
The model is built from published work by academic and industry teams, including Google and Oratomic, and is designed to be updated as new quantum research and hardware benchmarks emerge.
Revised qubit requirements shrink the threat horizon
Earlier public estimates suggested that breaking RSA‑2048 encryption would require on the order of 20 million physical qubits, implying that a CRQC was many years away.
Project Eleven reports that newer analyses from academic groups and industry labs, notably Google and Oratomic, have cut those qubit estimates by several orders of magnitude. The lower resource requirements compress the timeline for a practical quantum breaker and force a reassessment of when existing cryptographic systems may become unsafe.
A key driver of this compression is rapid progress in quantum algorithms and error‑correction techniques, which reduce both qubit count and runtime needed to attack real‑world keys.
Google research accelerates ECC risk
The report notes that in March 2026, Google’s Quantum AI team released research showing that the resources required to break elliptic curve encryption — used extensively in digital asset protocols — are significantly lower than previously assumed.
This update strengthens the case that:
- elliptic curve‑based schemes are likely to be among the earlier practical targets for a CRQC, and
- the “harvest now, decrypt later” strategy is no longer theoretical, as adversaries can archive encrypted traffic and on‑chain data today with an eye to decrypting it once quantum machines are capable.
Blockchain exposure and quantum‑sensitive holdings
Project Eleven highlights that exposure is already material on public blockchains.
- Approximately 33% of the total Bitcoin supply, or about 6.9 million BTC, is held in addresses where public keys are already visible on‑chain.
- These holdings are considered directly vulnerable in a post‑Q‑Day environment, because a CRQC could derive the private keys from these public keys and seize control of the funds.
The report stresses that this is not limited to Bitcoin; any blockchain where public keys are broadly exposed, or where migration pathways are unclear, faces similar structural risk once quantum attacks become feasible.
Technical model and analytical framework
The analysis is structured in two main sections:
- Quantum computing fundamentals and timeline model
- Explains how qubits, error correction, and quantum algorithms such as Shor’s algorithm interact to break classical encryption.
- Introduces a quantitative framework that tracks hardware scale, error rates, and algorithmic efficiency, generating a moving estimate of when a CRQC will be achievable.
- Cryptographic exposure of distributed ledger technologies
- Classifies common blockchain signature schemes and key‑management patterns by their quantum vulnerability.
- Identifies which protocol designs are most at risk and outlines staged migration paths to post‑quantum‑safe mechanisms.
Chief executive Pruden describes the model as an adaptable tool for scenario analysis and forecasting that will be refined as new results arrive from leading quantum labs. Chief technology officer Deegan emphasizes that many protocols built on elliptic curve signatures will require substantial engineering work to migrate to post‑quantum schemes.
Early experiments with post‑quantum signatures
Some networks are already experimenting with post‑quantum security, highlighting both feasibility and cost.
- In the Solana ecosystem, independent validator client teams have been testing quantum‑resistant signature schemes.
- Many have converged on Falcon, a lattice‑based algorithm selected by the U.S. National Institute of Standards and Technology (NIST) as part of its post‑quantum cryptography portfolio.
However, early benchmarks are stark:
- Implementing Falcon‑based signatures increased signature data size by up to 40x in some tests.
- Network throughput reportedly dropped by around 90%, underscoring the performance penalties associated with first‑generation post‑quantum primitives.
These results illustrate the trade‑offs Deegan referenced: improving quantum resilience often implies significantly larger signatures and higher computational and bandwidth overheads.
Size and performance penalties of new cryptography
The report notes that algorithm choice heavily influences costs.
- A signature using CRYSTALS‑Dilithium (standardized as ML‑DSA), another NIST‑approved post‑quantum scheme, is roughly 2,420 bytes.
- By contrast, typical ECDSA signatures used on major chains are about 72 bytes.
In Ethereum‑based benchmarking:
- Even the simplest Dilithium variant showed about 12% higher execution time across key generation, signing, and verification compared with ECDSA.
- While Dilithium is relatively efficient among post‑quantum candidates, these overheads compound at scale, affecting block sizes, fees, and throughput.
The report concludes that selecting and integrating post‑quantum schemes will require protocol‑level redesign, client optimization, and potentially new assumptions about node hardware and bandwidth.
Regulatory and standards push toward quantum readiness
Project Eleven situates these technical shifts within a firm policy backdrop.
- In August 2024, NIST finalized the first set of post‑quantum standards: FIPS 203, 204, and 205, providing official specifications for quantum‑resistant algorithms.
- U.S. federal agencies are now working under a defined transition roadmap that pressures the broader ecosystem to move.
Key milestones include:
- September 21, 2026: new U.S. federal procurements must use cryptographic modules validated under FIPS 140‑3, effectively nudging suppliers toward NIST’s post‑quantum standards.
- Post‑2030: quantum‑vulnerable algorithms are scheduled for deprecation in federal use, setting a de facto deadline for compliance across many technology supply chains.
Implications for blockchain systems and digital infrastructure
Project Eleven argues that the convergence of:
- shrinking quantum resource estimates,
- demonstrated blockchain‑level vulnerabilities, and
- a formal government transition schedule
creates a finite window for the industry to act.
The report stresses that meaningful upgrades — such as introducing dual‑stack classical/post‑quantum signatures, redesigning address formats, and migrating existing holdings from vulnerable to hardened schemes — will require years of coordinated work across core developers, exchanges, custodians, and infrastructure providers.
About Project Eleven and access to the report
Project Eleven focuses on building secure infrastructure for quantum‑resilient environments, with particular emphasis on cryptography and blockchain architectures that can withstand future quantum attacks.
The full 2026 “Quantum Threat to Blockchains” report, including the quantitative model, technical appendices, and migration recommendations, is available on Project Eleven’s website.
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