In a pivotal move within the cryptocurrency landscape, BlackRock has thrown its hat into the quantum-computing debate, releasing a report that underscores the potential risks that future advancements in quantum technology could pose to the cryptography underpinning Bitcoin, Ethereum, and the wider digital asset market. While the firm reassures that the cryptographic integrity of blockchains is not under immediate threat, it emphasizes the urgent need for the industry to begin post-quantum migration before what they term “Q-Day” becomes a security reality.
The report, titled “Quantum Computing and Blockchains,” was crafted by a team led by Will Su, Head of Digital Assets Research at BlackRock, along with Aladdin Digital Assets Lab’s Senior Software Engineer Inish Crisson and Robert Mitchnick, BlackRock’s Head of Digital Assets. It presents quantum computing as both a cybersecurity concern and a critical test of blockchain governance, particularly for networks relying on elliptic curve cryptography (ECC) for transaction signatures.
As stated in the report, “Quantum computing has been the subject of growing attention in recent years, particularly due to its implications for blockchains and many other elements of modern cyber infrastructure.” The authors argue that while quantum computing poses a manageable risk for blockchains, the industry’s proactive upgrades to post-quantum cryptography in the years ahead will be paramount.
Evaluating Bitcoin and Ethereum’s Core Risks
Interestingly, BlackRock points out that no Cryptographically Relevant Quantum Computer (CRQC) has been achieved as of yet. However, the timelines for development are tightening. The report highlights that Google has adjusted its post-quantum migration deadline to 2029, while IBM is targeting large-scale, fault-tolerant quantum computing capabilities between 2029 and 2033.
The core concern isn’t Bitcoin’s proof-of-work mechanism, which BlackRock describes as having a SHA-256 hash function that is largely quantum-resistant. The more pressing vulnerability lies in the ownership aspect—specifically, the digital signatures that authenticate control over coins.
Currently, both Bitcoin and Ethereum depend on elliptic curve cryptography for key ownership and transaction validation. According to the report, classical computers would take millions to billions of years to crack a 256-bit ECC, but a sufficiently advanced quantum computer utilizing Shor’s Algorithm could render this task significantly easier.
BlackRock notes, “The foundations of modern-day cryptography become challenged in the quantum world. This is not because quantum computers run faster, but due to their unique ability to uncover hidden patterns in vast datasets, employing quantum algorithms to tackle classically unmanageable problems like the Elliptic Curve Discrete Logarithm Problem (ECDLP) in mere days or even minutes.”
Bitcoin’s Migration: Technical Simplicity, Coordination Complexity
For Bitcoin, the transition to a post-quantum framework is technically simpler, as it primarily involves replacing a digital-signature algorithm. However, the real challenge lies in achieving social coordination within a decentralized network that is intentionally resistant to rapid changes.
BlackRock’s findings indicate that approximately 7 million BTC, or about 35% of the circulating supply, could be vulnerable to long-range quantum attacks due to exposed public keys. This number includes 1.9 million BTC held in address types that reveal unhashed public keys, alongside around 5 million BTC in reused addresses, which have similarly exposed public keys in past transactions while still retaining unspent transaction outputs (UTXOs).
The report also raises questions about the fate of inactive or lost coins, citing estimates from Chainalysis suggesting that between 2.3 million and 3.7 million BTC—representing 11% to 19% of the circulating supply—could be permanently unaccounted for. This group includes around 1.1 million BTC believed to belong to Satoshi Nakamoto.
BlackRock concludes, “From a technical standpoint, PQ migration for cryptocurrencies is eminently addressable; however, the key challenge remains timely coordination and implementation.” The report outlines that reaching consensus around post-quantum cryptography protocols, implementing blockchain upgrades, and executing ecosystem-wide migrations will likely span multiple years.
Ethereum: A Defined Path Amid Complexity
Ethereum’s landscape presents a different scenario. The report suggests that the Ethereum network possesses a more clearly defined migration strategy under the guidance of the Ethereum Foundation. Nonetheless, the technical complexities are heightened due to its proof-of-stake system, smart contract framework, data layer, and application-layer zero-knowledge systems.
BlackRock cites four potential vulnerability areas identified by Vitalik Buterin for Ethereum in early 2026: BLS signatures in the consensus layer, KZG proofs in the data layer, signatures for externally owned accounts, and zero-knowledge proofs in the application layer. Essentially, these areas encompass validator voting, data verification, user transactions, and application-level proofs—all of which depend on quantum-vulnerable cryptographic assumptions.
