Crypto Networks Map Out Quantum-Resistant Defenses

Quantum computers powerful enough to defeat public-key cryptography could eventually undermine the signatures that secure wallets and transactions on networks including Bitcoin, Ethereum and Solana. The Group of Seven is treating the transition to post-quantum cryptography as a long-term, economy-wide security project, warning that organizations need to inventory vulnerable systems and prepare upgrades before machines capable of practical attacks become available.

The G7’s latest warning says advances in quantum computing require action now, even though no large-scale cryptographically relevant system has been demonstrated. Crypto developers are weighing quantum-resistant signatures, wallet-address migrations and protocol changes across Bitcoin, Ethereum and Solana. Any rollout would need to balance security with performance, backward compatibility and decentralized governance, while persuading users to move funds from exposed or legacy addresses. The industry has not established a common implementation timetable.

Bitcoin, Ethereum and other major blockchains rely on elliptic-curve cryptography to authenticate transactions. A sufficiently capable quantum computer could derive private keys from public keys exposed onchain, allowing an attacker to sign valid transfers without breaching a wallet, device or exchange. That distinction matters because “Q-day” — when quantum machines can break standard public-key cryptography — may arrive without the conventional forensic evidence that normally identifies a security intrusion.

Christopher Smith, CEO and co-founder of Quantus Network, said on Aug. 10 that an initial attack could resemble scattered cases of lost or stolen keys. Targets may include Tether’s minting key rather than Satoshi Nakamoto’s Bitcoin holdings, valued at about $63 billion at the time. Google in March accelerated its post-quantum migration target to 2029, while Smith put the odds of cryptography-breaking capability emerging by 2028 at 50%.

A quantum computer capable of running Shor’s algorithm at scale could undermine the public-key cryptography securing online banking, cross-border payments, government communications and digital assets. Bitcoin may provide the earliest visible warning because its ledger is public and its assets offer attackers an immediate financial incentive. Experts say the larger obstacle is not the availability of post-quantum algorithms, but whether decentralized networks can coordinate a contentious migration before existing signatures become vulnerable.

The Swiss Bitcoin Institute said in a report published on Sept. 30, 2025, that a cryptographically relevant quantum computer could emerge within 10 to 20 years. Such a machine could put about 6.8 million Bitcoin at risk, worth roughly 600 billion Swiss francs and representing nearly one-third of total supply. The report cited a Hudson Institute estimate that a major quantum-enabled breach could inflict between $2 trillion and $3.3 trillion in indirect losses on the U.S. financial system.

Bitcoin uses elliptic-curve digital signatures to protect private keys and authorize transactions. If a large-scale quantum computer could use Shor’s algorithm to break public-key cryptography, assets could be transferred without authorization. The threat extends beyond Bitcoin, forcing Web3 to reassess the underlying security of wallets, nodes and cross-chain protocols.

The latest assessments indicate that quantum computers could threaten the security of Bitcoin private keys within the next 5–8 years. The Web3 ecosystem is therefore accelerating adoption of the post-quantum cryptography standards published by the U.S. National Institute of Standards and Technology (NIST) in August 2024. Reports have not disclosed the cost of the migration or a firm completion date.

Bitcoin and Ethereum rely on elliptic-curve digital signatures to secure transactions and asset ownership. If quantum computers become substantially larger and more stable, they could theoretically derive private keys. The U.S. Commerce Department’s support for the quantum industry therefore has implications beyond technological competition and is adding pressure on the crypto sector to accelerate its adoption of post-quantum cryptography.

As of July 20, 2026, the U.S. Commerce Department planned to invest more than $2 billion in nine quantum-computing companies to help scale the technology. The development has renewed concerns about the security of Bitcoin and Ethereum. Experts are calling for prompt planning of Post-Quantum Cryptography upgrades and closer coordination among governments, regulators and developer communities.

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.

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.

Quantum computers could threaten Bitcoin private keys and onchain assets if they become capable of breaking today’s elliptic-curve cryptography. BOLT Technologies founder Yoon Auh said adopting post-quantum cryptography would require more than a protocol overhaul. Large numbers of wallets, exchanges and holders worldwide would also need to migrate in coordination, testing the efficiency of decentralized governance.

The latest report focuses on whether Bitcoin governance can move quickly enough to address quantum risks, comparing the upgrade capacity of decentralized networks such as Ethereum with that of centralized systems. It gives no value for the assets at risk, potential date of a quantum attack or upgrade timetable. However, it stresses that assets held at legacy addresses could remain exposed if some wallets fail to migrate, even after the core protocol is updated.

Bitcoin and Ethereum both rely on elliptic-curve cryptography to secure transaction signatures. A practical quantum computer running Shor's algorithm could potentially derive private keys from public keys. Although the threat is not imminent, migrating on-chain assets and coordinating network-wide upgrades would take years. The two communities' ability to replace their cryptographic systems will therefore shape long-term security and market confidence.

On March 26, 2026, Castle Island Ventures partner Nic Carter criticized Bitcoin's slow response. ARK Invest estimated on March 11 that one-third of BTC was at risk. Ethereum has established a post-quantum roadmap for 2029, while Google has also set 2029 as its migration deadline. Bitcoin, meanwhile, is still discussing BIP-360.