StarkWare has put a quantum-safe Bitcoin transaction on mainnet, and the real story is narrower than the headline. It worked, but it doesn't make Bitcoin quantum-safe. On August 26, 2026, a strange Bitcoin transaction landed in block 964,199. It spent a 10,000-satoshi output using Avihu Levy's Quantum-Safe Bitcoin method, or QSB, and MARA Pool mined it after receiving it through its Slipstream service. According to StarkWare, it was the first quantum-safe Bitcoin transaction ever mined on mainnet. That's a real milestone. Keep it in proportion. Bitcoin didn't change its rules. No soft fork passed. No new wallet standard appeared overnight. Levy, StarkWare's general manager of applications, had published the QSB research in April, and StarkWare engineer Tomer Giladi later helped take the idea from paper and code into a live transaction. Decrypt also reported that StarkWare described the work as a test of protection against a future quantum attack without changing Bitcoin's consensus rules. The transaction worked because Bitcoin already had enough room Bitcoin normally relies on elliptic-curve cryptography, the math behind ECDSA and Schnorr signatures. A strong enough quantum computer running Shor's algorithm could eventually attack that setup. That is the fear sitting underneath every serious Bitcoin quantum discussion, even if the machine needed to do it still hasn't arrived. Vitalik Buterin has unveiled Lean Ethereum, a three to four year plan to rebuild Ethereum's consensus, cryptography and execution layers around quantum resistance, built-in privacy and steady scaling. Ethereum Foundation researcher Dankrad Feist and StarkWare's Eli Ben-Sasson both praised the vision but said the timeline is too slow. - Ethereum Lean protocol rebuild timeline - Vitalik Buterin Ethereum overhaul plan QSB takes a narrower route. It uses Bitcoin's existing legacy Script rules, hash-based one-time signatures, and what Cointelegraph described as computational searches that bind authorization to one specific transaction.