On 9 September, a team led by Jieyi Long (Theta Labs) published work started by Eigen Labs. More than a hundred people took part, with AI tools. This is not a hack. It is one step, on paper, of what would one day be needed to recover a Bitcoin or Ethereum private key from a public key. That step now costs less than at the start of summer. No computer, today, runs it.

Bitcoin and Ethereum sign with the same cryptography. A powerful enough quantum computer could, in theory, reverse that signature. The researchers did not build that machine. They lowered the theoretical price of a calculation that would come up often in such an attack. At the end of July, the challenge’s best result asked for 1,151 “logical” computing units — units already cleaned of errors, not today’s chips. That is 86% cheaper than the challenge’s starting point. It is not 86% below Google.

None of this is urgent because an attack is imminent. It is urgent because the remedy takes years and cannot be applied retroactively.— Jieyi Long, Theta Labs CTO, 10 September 2026

Google, and what the figure does not say

In March, Google Quantum AI published its own estimates. Eigen Labs writes that the new result sits more than 50% below that figure. The accounting methods are not the same: this is not an official win over Google, CoinDesk notes. A version closer to a real attack remains a little more expensive, still on paper. The challenge, StarkWare says, is not over.

Nobody has the machine

A “logical” unit is not a chip in a lab. It often takes thousands of physical ones to hold one. Today’s machines are not there. Nobody derives a key from this. Long adds that about a third of bitcoin already sits on addresses whose public key is visible. You cannot fix that after the fact. We wrote it with Charles Guillemet. ANSSI pushes to prepare tomorrow’s cryptography. Ethereum aims at end-2029 with Hegotá. This paper does not move that date. It only says: on paper, the cost fell.

What we hold

  • Held. Public work, 9 September. One step of a future attack would cost less than in June. 86% below the challenge’s start. More than 50% below Google in March, with different accounting. Long’s quote. Not a hack.
  • Not held. That Bitcoin or Ethereum is broken today. That 86% is against Google. That a machine exists. Advice to sell, buy, or move everything this morning.

Sources: the paper, Eigen Labs, Google, March 2026, The Quantum Insider, CoinDesk, StarkWare. Nothing here is investment advice.