StarkWare said it mined a 10,000-satoshi Quantum-Safe Bitcoin (QSB) transaction on Bitcoin’s mainnet on Aug. 26 without a soft fork, hard fork or core protocol upgrade. The transaction used MARA Foundation’s Slipstream service because its nonstandard format would not normally propagate through Bitcoin’s public mempool. Developed by researcher Avihu Levy, QSB combines hash-based one-time signatures with computational searches that bind authorization to a specific transaction, offering an opt-in defense while public keys are exposed. The test required hours of GPU computation and cost roughly $150 to $200, making it primarily a last-resort safeguard. Separately, Blockstream researchers published a Bitcoin Improvement Proposal on Aug. 27 for SHRINCS, a broader protocol approach whose signature is about 13.23 times smaller than an earlier large hash-based design but still nine times larger than Bitcoin’s existing signatures. Neither development makes Bitcoin universally quantum-resistant, and StarkWare CEO Eli Ben-Sasson continues to support a Bitcoin soft fork as a network-wide solution.