ME News, March 31 (UTC+8), Google's Quantum AI team has released a white paper presenting significant optimizations to Shor's algorithm. Shor's algorithm can break the elliptic curve cryptography used by Bitcoin and Ethereum; once quantum computers become powerful enough, attackers could derive private keys from public keys and steal funds. The team designed two attack circuits requiring fewer than 1,200 and fewer than 1,450 logical qubits—computational units formed by hundreds of physical qubits through error correction. On superconducting quantum computers, both circuits can complete computations in just minutes with fewer than 500,000 physical qubits. Previously, the academic consensus estimated around 10 million physical qubits; this breakthrough reduces the threshold by approximately 20 times.
Attackers can complete most preparatory computations in advance and crack private keys within about 9 minutes after a Bitcoin transaction is broadcast. With Bitcoin’s average block time of approximately 10 minutes, attackers have about a 41% chance of hijacking funds before the transaction is confirmed. Currently, around 6.9 million bitcoins (roughly one-third of the total supply) are at potential risk due to exposed public keys, with about 1.7 million originating from the early days of the network. Google also noted that the 2021 Taproot upgrade exposes public keys by default, potentially expanding the scope of vulnerable wallets.
The team did not publicly disclose the specific implementation of the attack circuit, but instead released a zero-knowledge proof that allows third parties to verify the validity of the conclusion without revealing the attack method. Ryan Babbush, Director of Quantum Algorithms at Google, and Hartmut Neven, Vice President of Quantum AI Engineering at Google, stated that the team had communicated with the U.S. government prior to publication and is currently collaborating with Coinbase, the Stanford Blockchain Research Institute, and the Ethereum Foundation to advance post-quantum migration. Google has previously set 2029 as its deadline for migrating its own authentication services to quantum-resistant cryptography. Nic Carter, co-founder of Castle Island Ventures, called the paper “highly alarming” and wrote: “Elliptic curve cryptography is on the brink of obsolescence. Whether it’s three years or ten, it’s over—we need to accept that.”(Source: 1M AI News)