Galaxy Digital Says Bitcoin Faces a Real Quantum Threat, but Not Yet an Existential Crisis

Bitcoin transactions use elliptic-curve digital signatures to protect assets. Once an address reveals its public key, a sufficiently powerful quantum computer could eventually derive the private key and steal the funds. The threat is not exploitable today, but the permanent public record of blockchain data means exchanges and long-term holders must plan ahead to migrate to quantum-secure addresses.

Coinbase’s independent advisory board on quantum computing and blockchain released a report on June 11, 2026, estimating that the public keys for about 7 million BTC have been exposed. About 1.7 million BTC are held in early P2PK addresses, while roughly 5 million BTC are exposed through address reuse and largely consist of active funds such as exchange cold wallets. Attackers can collect the data now and attempt to crack it later.

Bitcoin transactions rely on elliptic-curve digital signatures. A sufficiently powerful quantum computer could use Shor's algorithm to derive a private key from a public key, leaving older addresses whose keys have already been exposed at greatest risk. A February 2026 estimate put nearly 7 million BTC at risk, including about 1 million attributed to Satoshi Nakamoto, with a combined value of about $440 billion. The issue has implications for holders' property rights and consensus across the network.

On June 13, 2026, an independent quantum computing advisory board convened by Coinbase said quantum computers could not yet break Bitcoin but urged immediate planning for quantum-resistant signatures. It estimated that about 6.7 million BTC was at risk but did not endorse freezing or restricting older coins. A May 6 report from Project Eleven set 2033 as its baseline year for Q-Day, with 2030 as the earliest scenario.

Bitcoin transactions use elliptic-curve digital signatures to secure assets. A quantum computer running Shor’s algorithm could potentially derive private keys from public keys, putting older wallets and transaction security at risk. Ethereum, by contrast, has planned a mechanism allowing accounts to adopt quantum-resistant signatures, bringing corporate crypto treasury strategies and onchain governance capabilities into focus.

Google Quantum AI and other institutions published research on March 30, 2026, estimating that fewer than 500,000 physical qubits could crack a key in about nine minutes. Citi warned on May 18 that the potential attack timeline had shortened. Bit Digital had already announced on July 7, 2025, that it would sell about 280 Bitcoin and, alongside a $172 million fundraising, increase its holdings to 100,603 Ethereum.

Bitcoin uses elliptic-curve cryptography to protect assets and communications, but sufficiently powerful quantum computers could eventually break its current encryption. Experts say the more immediate danger is a “harvest now, decrypt later” strategy, in which attackers intercept and store large volumes of encrypted communications today, then recover sensitive historical data once the technology matures. The threat extends beyond wallet private keys.

Security experts and an early-stage venture investor have recently warned that historical communications and infrastructure data across the Bitcoin ecosystem may already be targets for quantum attacks. Ethereum has begun work on a post-quantum migration, but as of this report, neither Bitcoin nor related companies had publicly committed to specific safeguards, disclosed investment amounts or set completion dates. The upgrade timetable and division of responsibility therefore remain unclear.

Bitcoin and Ethereum rely on elliptic-curve cryptography to safeguard assets. A quantum computer capable of deriving a private key from a public key could potentially steal funds. Bitcoin activated Taproot on November 14, 2021, and because some transactions expose public keys in advance, the potential window for attack has widened.

The latest research from Google Quantum AI estimates that about 500,000 error-corrected physical qubits could be enough to crack a key within Bitcoin’s roughly nine-minute transaction confirmation window, far below previous estimates of several million qubits. No funds have been reported stolen through such an attack, but the researchers are urging the community to begin planning a migration to post-quantum cryptography.

Bitcoin uses elliptic-curve digital signatures to prove asset ownership. If a large-scale quantum computer could use Shor's algorithm to derive private keys, older addresses whose public keys have been exposed could be vulnerable to theft. Wall Street research and brokerage firm Bernstein said the risk is concentrated in Satoshi-era wallets holding about 1.7 million BTC, rather than posing an immediate threat to mining or the entire network.

Bernstein said on April 8, 2026, that Google had cut its estimate of the number of qubits needed to break the cryptography by about 20-fold to fewer than 500,000, but Bitcoin still had three to five years to upgrade. On April 13, the firm said BTC's nearly 50% retreat from its October 2025 peak of $126,198 had already priced in most of the quantum risk. The real challenge, it said, lies in securing community consensus and migrating wallets.

Quantum computers capable of breaking public-key cryptography could threaten Bitcoin signatures and asset ownership, making the technology a long-term market risk. Strategy, formerly MicroStrategy, co-founder and Executive Chairman Michael Saylor said banks, the internet and crypto assets all face the same pressure to upgrade, while Bitcoin could adopt quantum-resistant cryptography through updates to its nodes, wallets and protocol.

Saylor told Natalie Brunell’s “Coin Stories” on Feb. 23, 2026, that any quantum breakthrough posing a material threat was at least 10 years away. At a Mizuho event on April 8, he again said the risk was overstated and could be addressed through upgrades. He also said Bitcoin had likely bottomed at about $60,000 in early February; its price was around $71,200 when the report was published on April 9.

Bitcoin uses a proof-of-work mechanism, and an attacker controlling more than 50% of the network’s computing power could theoretically reorganize its transaction history. An academic research team found that while quantum computing could accelerate calculations, a 51% attack on Bitcoin mining would still face physical constraints including hardware scale, cooling and energy supply, limiting the near-term threat.

As of July 20, 2026, the latest research estimates that a quantum computer powerful enough to overwhelm the entire Bitcoin network could require energy on the scale of a star, putting such a system beyond what existing institutions could deploy with funding alone. A more practical risk is the compromise of older wallets whose public keys remain exposed. Bitcoin developers have begun exploring quantum-resistant signatures and network upgrades.

Quantum computers could eventually break the elliptic-curve digital signatures Bitcoin currently uses, putting early addresses with exposed public keys and dormant assets at risk. Grayscale said viable post-quantum cryptographic solutions already exist. The key question is whether Bitcoin can migrate its network protocol and wallets before the threat becomes viable.

Grayscale’s latest research said the main bottleneck is not engineering capability but how the decentralized community handles vulnerable early addresses, whether it restricts legacy signatures and which upgrade path it uses to reach consensus. The report did not disclose potential losses, a specific publication date or a timeline for quantum attacks, but warned that governance delays could prolong the transition.

Quantum computers capable of breaking Bitcoin's current elliptic-curve digital signatures could potentially steal assets from older addresses whose public keys have been exposed, including holdings attributed to Satoshi Nakamoto. The threat is therefore seen as existential. Martin Gaspar, senior crypto market strategist at FalconX, compared the issue with the 2021 controversy over the energy use and climate impact of Bitcoin's proof-of-work system, which also weighed on investor confidence.

In an analysis published by CoinDesk on March 4, 2026, Gaspar noted that Strategy announced a quantum-security initiative on February 5 as Bitcoin plunged toward $60,000. Coinbase also established a quantum computing and blockchain working group, while Project Eleven and BTQ Technologies are developing post-quantum technology. Gaspar said quantum concerns would recede like the earlier climate panic as the industry provides data, protection recommendations and migration plans.