Quantum-safe Bitcoin just got 4× more reachable: emergency compute drops to $66 🧠

The cost of building a quantum-resistant $BTC transaction without changing the network's consensus rules has fallen below $67, down from roughly $320 on the first such mainnet transaction in August, according to StarkWare. The latest reductions stem from a weeklong optimization challenge and have only been demonstrated in benchmark tests so far.

"A construction that costs a few hundred dollars per transaction is a demo. One that costs $67 is closer to something a holder with a large unexposed balance might reach for in an emergency," StarkWare wrote in its Sept. 23 update. The dashboard now shows the estimated cost at $66.

The Quantum-Safe Bitcoin (QSB) design was published in April by StarkWare researcher Avihu Levy, who described it as a "last resort measure" due to costs, complexity and limited applicability, while continuing to advocate for protocol-level changes. The first QSB transaction was mined and confirmed on Aug. 26, with engineering work from Tomer Giladi and direct submission through MARA's Slipstream service. Preparing it required approximately 3,100 GPU-hours across roughly 100 GPUs, at a compute cost of about $320, excluding Bitcoin network fees.

To bring costs down, StarkWare, Yukon Research and Eigen Labs launched the QSB challenge on Sept. 16, inviting developers, researchers and AI agents to speed up the transaction-building software. StarkWare said the challenge produced 62 accepted improvements across two computational tasks needed to prepare a QSB transaction, cutting the estimated computing cost by about 79% based on benchmark tests.

The development comes amid concern that a sufficiently powerful quantum computer could break the elliptic-curve digital signatures used by Bitcoin, potentially allowing attackers to steal coins whose public keys are exposed. Researchers are developing quantum-resistant protections, including QSB, but StarkWare said it still favors a soft fork — a change to Bitcoin's consensus rules — as a better "long-term answer" for broad quantum protection on $BTC.