A team of investigators has successfully reduced the projected resources necessary for a critical operation involved in a potential quantum strike against Ethereum and Bitcoin. Based on a technical document produced by Theta Labs CTO Jieyi Long along with specialists from various academic organizations and cryptographic initiatives, their specific circuit demands 1,151 logical qubits alongside 1.30 million Toffoli gates.
The scientists quantify the resource burden of the circuit by multiplying its required logical qubits—which serve as its active memory—by the quantity of Toffoli gates, which represent the operations responsible for the bulk of its execution time. Multiplying these two metrics yields a single score where a smaller value signifies a superior, more efficient circuit. Across a span of roughly two months, community entries submitted to an open contest drove this metric down by 86%, moving it from 10.75 billion to 1.496 billion. Furthermore, this final metric came in at under half of the benchmark previously disclosed by Google.
Google Quantum AI shared its own projections back in March, establishing a 2029 deadline for transitioning to post-quantum cryptography, though it withheld the underlying circuit designs. While omitting the circuit itself, the company provided a zero-knowledge proof verifying that a valid circuit existed, along with a public verifier tool capable of testing alternate circuits and computing their associated expenses. Leveraging that application, Eigen Labs introduced ECDSA.Fail on May 30, opening the door for external contributors to propose optimizations.
In total, upwards of 100 individuals participated in the contest, featuring engineers and academics tied to Eigen Labs, StarkWare, the Ethereum Foundation, the Starknet Foundation, Theta Labs, Brevis, Trail of Bits, and Sei Labs.
The study’s authors emphasized that this undertaking does not constitute an active attack. They explained that the circuits omit physical error correction mechanisms and fail to represent a complete execution of Shor’s algorithm. The documentation pointed out that Google relied on distinct interfaces and accounting metrics, framing the comparison as numerical context rather than a formal assertion that the fresh circuit surpassed Google’s performance.
Investigators kept filing enhancements even after the publication’s cutoff deadline for challenge entries, achieving milestones such as a design requiring 952,707 Toffoli gates and another utilizing only 813 logical qubits, according to the team.
Crypto Networks Prepare for Quantum Threat
This study emerges as developers across both Ethereum and Bitcoin actively prepare for prospective future quantum vulnerabilities. In June, Coinbase’s Independent Advisory Board on Quantum Computing and Blockchain calculated that approximately 7 million BTC reside in addresses vulnerable to a future quantum assault because their corresponding public keys remain visible on-chain. This figure encompasses assets stored in legacy formats as well as coins exposed through repeated address reuse, though the board underscored that current quantum machines remain incapable of compromising blockchain cryptography today. Meanwhile, Ethereum aims to achieve comprehensive post-quantum defense spanning its consensus, execution, and data tiers by December 2029.
“None of this is urgent because an attack is imminent,” stated Long of Theta Labs. “It is urgent because the remedy takes years and cannot be applied retroactively.”
Eli Ben-Sasson, CEO and co-founder of StarkWare—whose personnel also took part in the project—shared with The Block that he experienced “butterflies” when his staff presented him with the discoveries. Ben-Sasson noted, “Cutting the cost of breaking Bitcoin’s cryptography in half, in two months means that everyone should sit up and take notice. If the estimate of what it costs to break this cryptography is being cut in half, as it is in this paper, then every timeline anyone has quoted you for Q-Day needs to be cut too. You don’t get to keep the old comfortable number just because the computer isn’t built yet.”
Originally published at https://www.theblock.co/news/ecosystems/2026-09-10-researchers-halve-quantum-resource-benchmark-for-key-operation-in-bitcoin-ethereum-attack-414121.
