StarkWare and the MARA Foundation announced what they call the first known quantum-resistant Bitcoin transaction, a Quantum-Safe Bitcoin (QSB) construction designed by Avihu Levy, advanced with engineer Tomer Giladi, and mined by MARA Pool in block 964,199 on August 26, 2026, with related coverage dated around August 27. The method uses hash-based security and signature grinding so eligible coins can be moved into storage a quantum computer cannot open without changing consensus rules, though the nonstandard format required direct submission through MARA’s Slipstream private mempool rather than ordinary relay. StarkWare CEO Eli Ben-Sasson called the milestone huge for a post-quantum path and proof that workable solutions exist, while still urging a soft fork as the long-term fix and stressing Bitcoin is not yet prepared. QSB cannot protect addresses with already-exposed public keys, leaves older pay-to-public-key outputs, Taproot outputs, reused addresses and already exposed coins vulnerable, and incurred several hundred dollars of off-chain computation in the live test. Separately, Adam Back’s Blockstream released a Bitcoin Improvement Proposal for a post-quantum signature scheme dubbed SHRINCS, described as a strong trade-off among options for a network-wide upgrade, while Polymarket priced only about a 5% chance of such an upgrade this year. In June, Coinbase’s quantum advisory council estimated roughly 7 million bitcoin could be vulnerable through exposed public keys and address reuse, while Glassnode Research separately estimated 6.04 million BTC, or about 30.2% of supply, exposed at rest; in July, BlackRock, Coinbase, Strategy and six other institutions formed the Bitcoin Security Consortium and pledged a combined $15 million over three years for Bitcoin security research, including post-quantum cryptography.