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.

• Google's paper shows Shor's algorithm could break Bitcoin/Ethereum's 256-bit ECC with under 500,000 physical qubits in about nine minutes—roughly Bitcoin's block time.
• Even though Google withheld exact circuit details, the disclosed architecture (kickmix design, modular inversion, ~2.7 million non-Clifford gates per point addition) gives skilled teams enough to replicate similar circuits within months.
• Goertzel estimates a small expert team could reproduce circuits within 2-3x Google's efficiency in 6-12 months, and even a 2x-worse circuit would still threaten current cryptography.
• The real barrier isn't algorithmic knowledge but building the actual hardware, though well-funded labs or defense contractors could plausibly pursue it.

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.

• A neutral-atom qubit approach could crack 256-bit ECC in 10 days using 100x less overhead than prior estimates.
• A Google team claims to break ECC securing Bitcoin-like cryptocurrencies in under nine minutes, a 20-fold resource reduction.
• Neither whitepaper has been peer-reviewed, so the claims remain unverified.
• Experts say the results don't pin down a timeline for practical quantum decryption, but confirm steady, unslowing progress toward it.