Introduction

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This report examines quantum computing risk in the context of institutional blockchain strategy. The analysis draws on primary sources including NIST publications, BIS papers, G7 Cyber Expert Group statements, and independent expert surveys to assess whether quantum computing should alter long-horizon blockchain deployment decisions.

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As financial institutions evaluate blockchain systems for custody, settlement, and tokenized assets, quantum computing is frequently cited as a reason for caution. This report examines the current state of quantum hardware, probability-weighted CRQC timelines, Ethereum’s post-quantum roadmap, and the strategic implications of delay.

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This article outlines the report’s key findings on threat timelines, blockchain-specific exposure, governance capacity, and institutional decision frameworks.

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Key Findings

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1. Quantum Computing Is a Strategic, Not Imminent, Threat

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Industry consensus places the earliest realistic cryptographically relevant quantum computer in the early-to-mid 2030s. Current systems cannot break deployed cryptographic standards. Probability of CRQC before 2030 remains below 15% under the most comprehensive expert surveys.

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2. Blockchain Exposure Is Often Mischaracterized

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“Harvest now, decrypt later” primarily threatens encrypted communications such as TLS and stored ciphertext.

For blockchain systems, the primary quantum exposure is future key derivation from publicly exposed keys, enabling signature forgery if migration does not occur. This distinction materially changes mitigation strategy.

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3. Ethereum Has a Structured Post-Quantum Roadmap

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Ethereum’s phased transition includes research, testnets, hybrid migration, and full deprecation of classical signatures, targeting completion around 2030. Under median threat forecasts, this creates an estimated 3–5 year safety margin.

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4. Regulatory Timelines Converge on the Same Window

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NIST standardization, NSA federal migration targets, NCSC UK guidance, and BIS analysis all converge on a mid-2030s horizon for cryptographic migration. Ethereum’s roadmap aligns with these expectations.

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5. Delay Carries Strategic Cost

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The institutional learning curve for blockchain integration spans multiple years. Delaying adoption does not reduce quantum exposure across existing infrastructure. It postpones capability development while maintaining dependency on vulnerable asymmetric cryptography.

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Conclusion

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Quantum computing represents a credible long-term shift in cryptographic assumptions. It does not justify institutional paralysis.

The probability-weighted timeline provides runway for migration. Ethereum’s roadmap targets completion ahead of the most probable threat window. Regulatory guidance converges on the same horizon.

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The appropriate posture is structured preparation.

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