BlackRock is framing quantum computing as a serious but manageable long-term risk for Bitcoin and Ethereum, provided blockchain networks move early enough toward post-quantum cryptography. In a June report titled Quantum Computing and Blockchains, Will Su, BlackRock’s head of digital assets research, Inish Crisson, senior software engineer at Aladdin Digital Assets Lab, and Robert Mitchnick, BlackRock’s head of digital assets, argue that the core issue is less whether blockchains can technically upgrade and more whether decentralized ecosystems can coordinate those upgrades before a cryptographically relevant quantum computer emerges.
BlackRock Sees Quantum Risk as Manageable For Bitcoin And ETH
BlackRock’s report places crypto within a broader cybersecurity transition affecting banks, web browsers, government communications, SWIFT transfers and other systems that rely on RSA or elliptic curve cryptography. The authors write that quantum computing could eventually threaten the public-key systems used across modern digital infrastructure, but they stress that the threat has not yet materialized. “No functional CRQC exists today, and significant physics, technical, and engineering hurdles remain before one could become feasible. Yet recent breakthroughs have pulled forward quantum timelines from technology leaders in the field: Google is moving up its migration deadline to 2029 and IBM is targeting large-scale fault-tolerant quantum computing by 2029-2033.”
For crypto markets, BlackRock identifies digital assets as a prominent target because blockchains are transparent, liquid and directly monetizable. Bitcoin’s proof-of-work history, secured by SHA-256, is described as broadly resistant to quantum attack because Grover’s Algorithm offers only a limited speed advantage that Bitcoin’s difficulty adjustment could absorb. The more exposed area is transaction ownership: Bitcoin, Ethereum and many other blockchains currently rely on elliptic curve digital signatures, which could become vulnerable if a sufficiently capable quantum computer were able to run Shor’s Algorithm at scale.
Still, BlackRock’s central conclusion is that crypto’s quantum problem is addressable. “In our view, PQ migration for cryptocurrencies is eminently addressable from a technical standpoint, and the key challenge is one of timely coordination and implementation. When Bitcoin was first launched in the late 2000s, its pseudonymous creator Satoshi Nakamoto addressed the possibility of underlying cryptographic primitives being broken and discussed how the network could lock in the honest chain and transition to stronger algorithms.” The report adds that the end-to-end process of selecting post-quantum protocols, implementing network upgrades and migrating users will likely take several years.
The report notes that the post-quantum standards process is already well advanced outside crypto. The National Institute of Standards and Technology launched its post-quantum cryptography standardization initiative in 2016 and has finalized three standards: ML-KEM for key encapsulation, ML-DSA as a primary digital signature standard and SLH-DSA as a hash-based backup signature standard. BlackRock also highlights that public and private migration timelines are moving forward, with many governments targeting full migration by 2035, while Google and Cloudflare are targeting 2029.
BlackRock’s risk framing is especially relevant for Bitcoin because a measurable share of circulating supply is already exposed to long-range quantum attack if a CRQC becomes available. The report estimates that nearly 7 million BTC, or about 35% of circulating supply, is potentially vulnerable because public keys have been exposed through address types or address reuse. That figure includes 1.9 million BTC in address types that expose unhashed public keys and another 5 million BTC in addresses whose public keys were revealed in prior transactions while still holding unspent outputs.
The report also highlights a sensitive unresolved issue: coins that cannot migrate because private keys are lost or owners are inactive. “Migration is not possible for UTXOs held in inactive addresses with deceased owners or lost private keys, including the ~1.1 million in P2PK addresses widely believed to be owned by Satoshi Nakamoto. Chainalysis estimates 2.3-3.7 million BTC (11-19% of circulating supply) may be permanently lost based on long-term dormancy analysis.” BlackRock says the treatment of those holdings remains an active debate in the Bitcoin community, with possible paths ranging from leaving vulnerable coins spendable to eventually making unmigrated balances unspendable after a defined transition period.
Crypto’s Post-Quantum Shift Hinges on Coordination
Bitcoin’s path is described as technically narrower than Ethereum’s but socially more difficult. BlackRock says replacing Bitcoin’s signature scheme is a comparatively contained protocol change, yet Bitcoin’s decentralized governance makes agreement on timing, standards and migration mechanics slow by design. Several post-quantum Bitcoin Improvement Proposals have entered the repository in draft form, and the report points to proposals involving Taproot script paths, quantum-resistant opcodes and new signature schemes that could reduce exposure to long-range and short-range attacks.
Ethereum faces a different profile: more structured planning but greater technical complexity. BlackRock cites Ethereum co-founder Vitalik Buterin’s identification of four quantum-vulnerable areas across Ethereum: BLS validator signatures in the consensus layer, KZG proofs in the data layer, externally owned account signatures and zero-knowledge proofs in the application layer. The Ethereum Foundation’s “L1 Strawmap” lays out a series of planned upgrades between 2026 and 2029, including native account abstraction, post-quantum signature precompiles, post-quantum validator keys and a transition from KZG commitments toward STARK-based proofs for data verification.
The report also notes early post-quantum activity elsewhere in the crypto ecosystem, including Solana’s Winternitz Vault for moving assets to post-quantum addresses and Algorand’s execution of a post-quantum-signed mainnet transaction. But BlackRock says exchanges, custodians, validators and wallet providers will also need to update hardware, software and policies over a multi-year period. “In concert with the underlying blockchain protocols, the broader digital assets ecosystem, including exchanges, custodians, and validators, will also need to upgrade hardware, software, and policies to become quantum-secure over a multi-year timeframe.”
The practical challenge is that post-quantum signatures can be much larger than today’s ECC or Schnorr signatures, creating pressure on block space, transaction costs and network design. BlackRock cites SLH-DSA signatures of roughly 7.8 KB, more than 100 times larger than signatures commonly used today, while noting that more compact alternatives such as SHRINCS and SHRIMPS are under development. These trade-offs make implementation choices important for throughput, privacy, application flexibility and fee markets.
BlackRock’s broader view is that the defensive side still has the advantage because upgrading cryptographic systems is less difficult than building a functioning CRQC from today’s technology base. The report points to major resource gaps that remain in quantum hardware, error correction and environmental isolation, even as algorithmic improvements have reduced estimates for the number of qubits needed to attack ECC-256. “Fundamentally, it is a much less daunting task to upgrade current cryptographic systems (including Bitcoin) to a quantum-secure standard than it is to build a CRQC, from where quantum computing progress stands today. Thus, advantage remains decidedly with the Defense at the current juncture.”
BlackRock’s report treats quantum computing as neither an immediate crisis nor a risk crypto can ignore. Its assessment is that Bitcoin, Ethereum and other blockchains can migrate to quantum-secure cryptography, but the work must begin well before “Q-Day” to avoid market disruption and unresolved governance disputes. If those migrations are executed cleanly, BlackRock argues that digital assets could emerge with stronger infrastructure and reduced long-term security concerns.
AI Transparency Note: This article was prepared with the assistance of an AI system based on the sources listed and was reviewed, edited, and approved by a human editor before publication. All quotes, data points, and factual claims are intended to be grounded in the cited source material; however, errors cannot be ruled out entirely.
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