Quantum Computing’s Shadow Grows Over Bitcoin and Ethereum Security

Researchers are stepping up efforts to defend major blockchain networks against a threat that once sounded distant: quantum computers capable of breaking the cryptography that protects digital wallets.

The concern centers on how cryptocurrency transactions work. When users spend from a Bitcoin or Ethereum address, they expose a public key to the network. With today’s classical computers, deriving the corresponding private key from that public key would take longer than the age of the universe. A sufficiently large quantum machine running Shor’s algorithm, however, could theoretically complete the task in minutes.

New estimates from Google Quantum AI, a unit of Alphabet, put concrete numbers on the requirement. According to a March paper co-authored by researchers from the Ethereum Foundation and Stanford University, breaking the encryption would take roughly 1,200 to 1,450 logical qubits — reliable qubits built by combining hundreds of error-prone physical qubits. On superconducting hardware, that translates to fewer than 500,000 physical qubits and a runtime of 18 to 23 minutes.

Those figures matter because they suggest the engineering gap, while still enormous, is no longer abstract. Cryptographers and blockchain developers are responding with post-quantum cryptographic schemes — new signature algorithms designed to resist attacks from quantum machines — and weighing how to migrate billions of dollars in on-chain assets to quantum-resistant addresses without disrupting the networks.

The development also lands amid broader investor attention to quantum-related equities. Shares of Quantum Corporation, a data management and storage hardware company, traded down about 1.13% to $24.24, valuing the firm at roughly $955 million. Alphabet’s stock, meanwhile, slipped 1.3% to $338.46, giving the search and cloud giant a market capitalization of approximately $4.14 trillion. Neither company’s daily move is directly tied to blockchain security research, but both illustrate the market’s current posture toward names associated with quantum technology.

For the crypto industry, the stakes are structural. Bitcoin and Ethereum both rely on elliptic-curve signatures, the same class of mathematics targeted by Shor’s algorithm. A successful migration to quantum-safe signatures would rank among the largest coordinated upgrades in the history of open-source software, requiring consensus across developers, miners, validators, and users.

Alphabet’s involvement through Google Quantum AI underscores that the research is no longer confined to academia — large technology companies are publishing roadmaps that define exactly what scale of hardware would threaten existing cryptographic standards.

What to watch

• Follow-up publications from Google Quantum AI and its academic collaborators on qubit scaling and error-correction milestones.
• Proposals from Bitcoin and Ethereum developers on post-quantum signature standards and migration timelines.
• Alphabet’s next quarterly earnings report, which may include updates on its quantum computing program.

Source: original release