Crypto researchers cut Bitcoin and Ethereum quantum attack estimate by 50%

Researchers from the Ethereum Foundation, Theta Labs, StarkWare, and several other organizations have published findings cutting the estimated computing resources needed for a key step in a quantum attack on Bitcoin and Ethereum by more than 50%. Working alongside artificial intelligence coding agents via Eigen Labs' open ECDSA.Fail challenge, the team optimized point addition calculations used in Shor's algorithm, which targets the secp256k1 elliptic curve cryptography underpinning both networks. The resulting quantum circuit design utilizes 1,151 logical qubits and approximately 1.3 million Toffoli gates, achieving a benchmark score of roughly 1.5 billion compared to the 3 billion reported by Google Quantum AI earlier this year. A subsequent variation reduced requirements down to 813 logical qubits at the expense of additional computation. While existing quantum hardware remains incapable of breaking current cryptographic defenses today, experts warn that algorithmic optimizations reduce the hardware threshold required for future attacks. Because deploying quantum-resistant protocol upgrades across decentralized blockchains requires years of consensus and implementation, researchers emphasize the urgent necessity of preparing post-quantum cryptographic defenses.