Circle's August 31 Disclosure Reads 813 Logical Qubits Off Eigen Labs' ECDSA.fail Leaderboard: What a Google and Stanford Estimate Says a secp256k1 Attack Actually Costs

Circle's August 31 disclosure tells developers that breaking elliptic curve signatures now takes 813 logical qubits, a figure lifted from one axis of Eigen Labs' ECDSA.fail circuit competition. We put it back beside the March 2026 Google, Stanford, and Ethereum Foundation estimate, under 1,200 logical qubits and 90 million Toffoli gates on fewer than half a million physical qubits, and beside Willow's actual 105 physical qubits, to show how a defense buyer should read quantum cryptanalysis headlines while setting a post-quantum migration schedule.