This article debunks the idea that quantum computers halve the security of symmetric keys via Grover’s algorithm, showing that the required depth and parallelization make an AES-128 key search infeasible. Concrete gate-count estimates and NIST’s MAXDEPTH guidelines confirm that AES-128 (and larger keys) remain secure against practical quantum attacks.

Google’s recent paper reveals that Shor’s algorithm can potentially break the cryptography used by Bitcoin and Ethereum with fewer than 500,000 qubits. The paper discloses significant architectural details, suggesting that reproducing similar circuits is feasible for well-resourced quantum research teams. However, the actual hardware needed for an attack remains a substantial barrier.

Recent research indicates that building a quantum computer capable of breaking elliptic-curve cryptography (ECC) is becoming easier and faster than previously thought. One study shows it could crack ECC in just 10 days, while another demonstrates breaking ECC-secured blockchains in under nine minutes. Both papers highlight significant progress in quantum computing capabilities, though neither has been peer-reviewed.