Google Slashes Quantum Resource Requirements for Breaking Cryptocurrency Encryption

Google’s Quantum AI research division has published a whitepaper warning that the cryptographic foundations of most major cryptocurrencies are more vulnerable to quantum attacks than previously believed.

The findings suggest that the timeline for when quantum computers could pose a real threat to blockchain security may be shorter than previously assumed.

At issue is elliptic curve cryptography (ECC), the mathematical system that secures Bitcoin, Ethereum, and most other blockchains. Quantum computers running Shor’s algorithm can in theory break ECC, but until now the consensus was that doing so would require a very powerful quantum machine.

Google’s new estimates significantly lower the threshold. The company’s researchers have designed quantum circuits capable of breaking the 256-bit elliptic curve discrete logarithm problem (ECDLP-256) used by cryptocurrencies.

Specifically, they achieved this using fewer than 1,200 logical qubits and around 90 million Toffoli gate operations, which roughly represents a 20-fold ...