Cracking Bitcoin in just 9 minutes? Google warns that the end of elliptic encryption may come sooner than expected, having lowered the attack threshold by 20 times.

ME News update: On March 31 (UTC+8), Google’s Quantum AI team released a white paper showing major optimizations to the Shor algorithm. The Shor algorithm can break the elliptic-curve encryption used by Bitcoin and Ethereum; once quantum computers are powerful enough, attackers can derive private keys from public keys and steal funds. The team compiled two sets of attack circuits, each requiring fewer than 1,200 and fewer than 1,450 logical qubits (computing units made up of hundreds of physical qubits with error correction). On superconducting quantum computers, both circuits can complete the computation within a few minutes under the condition of fewer than 500,000 physical qubits. Previously, the mainstream estimate in academia was about 10 million physical qubits; this breakthrough lowers the threshold by roughly 20 times.

Attackers can complete most of the preparatory computations in advance, cracking the private key about 9 minutes after Bitcoin transaction broadcast. Bitcoin’s average block time is about 10 minutes, giving attackers about a 41% chance to hijack funds before the transaction is confirmed. Currently, around 6.9 million Bitcoins (about one-third of the total supply) face potential risk because their public keys have been exposed; about 1.7 million come from the network’s early days. Google also noted that the Taproot upgrade in 2021 exposes public keys by default, which may further expand the scope of vulnerable wallets.

The team did not publicly disclose the specific implementation of the attack circuits, but instead released a zero-knowledge proof that allows third parties to verify that the conclusion is correct without revealing the attack method. Ryan Babbush, Director of Quantum Algorithms Research at Google, and Hartmut Neven, Vice President of Engineering for Google Quantum AI, said the team had already communicated with the U.S. government before publication and is now working with Coinbase, the Stanford Blockchain Research Institute, and the Ethereum Foundation to advance post-quantum migration. Google previously set 2029 as the deadline for migrating its own certified services to post-quantum cryptography. Nic Carter, co-founder of Castle Island Ventures, called the paper “very sobering,” and wrote: “Elliptic-curve cryptography is on the edge of being obsolete. Whether it’s 3 years or 10 years, it’s over—we need to accept that.” (Source: 1M AI News)