Quantum Attack Estimate For Bitcoin And Ethereum

Researchers working with AI agents cut quantum attack estimates for Bitcoin (BTC) and Ethereum (ETH) by more than 50% this week by beating a benchmark Google set in March on a core calculation behind Shor’s algorithm.

Key Takeaways

Researchers cut quantum attack estimates for Bitcoin and Ethereum by more than 50% this week
The work used AI agents to optimize a calculation underlying Shor’s algorithm, beating a Google benchmark from March
Quantum attack estimates for breaking Bitcoin’s signature scheme have historically ranged from several million to over a billion physical qubits
No blockchain has announced a hard deadline for quantum-resistant signatures

The result, detailed in a paper that researchers shared Thursday, narrows the gap between today’s quantum hardware and the theoretical machine capable of breaking the elliptic curve cryptography securing both blockchains. It landed as cryptographers and exchanges have spent two years quietly stress-testing how much runway blockchain security has left.

The qubit count required to run that attack is the industry’s most-watched number because it converts an abstract threat into a rough timeline, a 50% drop does not mean quantum computers can break Bitcoin today, but it does mean the hardware finish line moved substantially closer.

How Shor’s Algorithm Shapes The Quantum Attack Estimate

Shor’s algorithm, proposed in 1994, can factor large numbers and solve the discrete logarithm problem far faster than any classical computer.

Bitcoin and Ethereum both rely on elliptic curve cryptography, a scheme that generates private keys from public keys using a problem believed intractable for classical machines but theoretically solvable by a sufficiently large quantum computer running Shor’s algorithm.

Also Read: Tom Lee Issues Bold $6000 Ethereum Target With $150000 Bitcoin Condition

Quantum attack estimates for breaking Bitcoin’s signature scheme have historically ranged from several million to over a billion physical qubits, depending on error-correction assumptions, dwarfing the roughly 1,000-qubit machines that exist today.

From Benchmark To An Open Question About Migration

Google published a benchmark improvement to the underlying calculation in March. The new work reportedly used AI agents to optimize that same calculation rather than relying solely on human cryptographers.

Ethereum developers have separately discussed post-quantum signature migrations in Ethereum improvement proposal discussions over the past year, while Bitcoin’s quantum-resistance debate has simmered on developer mailing lists since 2024 without a shipped fix.

No blockchain has announced a hard deadline for quantum-resistant signatures, and the paper’s core numbers deserve scrutiny over what error-correction assumptions they embed before treating this as a definitive timeline shift.