StarkWare’s quantum-safe last-resort solution for Bitcoin has become 79% cheaper.

StarkWare said the estimated computational cost to prepare a Quantum-Safe Bitcoin transaction has fallen below $67 after a week of optimization, down from roughly $320 spent on the first such mainnet transaction in August. The reduction came after participants in the Quantum-Safe Bitcoin Optimization Challenge found ways to push down the GPU computation needed to build a quantum-safe Bitcoin transaction. StarkWare’s September 23 update said the dashboard now shows the estimated cost has dropped to $66.

Why the lower cost matters

The experiment is aimed at an emergency defense against future quantum attacks that would not require changes to Bitcoin’s consensus rules. If the cost of preparing a transaction falls enough, it could become more practical for Bitcoin holders who need to move funds without waiting for a broader protocol change.

StarkWare framed the difference between a demonstration and a usable fallback in its update. “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.

The company also stressed limits. The latest optimizations have only been demonstrated in benchmark tests, so the result does not mean every holder can or should use the method today. The cost reduction is a step toward usability, not a finished protection product.

From $320 to $66 in one month

The Quantum-Safe Bitcoin design was published in April by StarkWare researcher Avihu Levy. It outlines a way to add hash-based protection against quantum attacks without changing Bitcoin’s consensus rules. At the time, Levy described it as a “last resort measure” because of costs, complexity and limited applicability, while continuing to advocate for protocol-level changes.

The first transaction based on the design was mined and confirmed on August 26, according to StarkWare. The engineering work was done by Tomer Giladi, and the transaction was submitted directly 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 reduce that cost, StarkWare, Yukon Research and Eigen Labs launched the Quantum-Safe Bitcoin Optimization Challenge on September 16. The challenge invited developers, researchers and AI agents to make the transaction-building software faster and more efficient.

StarkWare said the challenge produced 62 accepted improvements across two computational tasks needed to prepare a Quantum-Safe Bitcoin transaction. Based on benchmark tests, those improvements cut the estimated computing cost by about 79%. The estimated cost fell by another dollar since publication, according to the source Yukon.

The quantum risk behind the design

The work responds to a concern that a sufficiently powerful quantum computer could break the elliptic-curve digital signatures used by Bitcoin. That could potentially allow attackers to steal coins whose public keys are exposed.

The design’s hash-based protection is intended to address that risk without replacing the network’s current rules. 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 Bitcoin.

What readers should watch next

The next question is whether benchmark savings can hold under real mainnet conditions, including reliability, tooling and practical access for holders. Until then, the $67 figure should be read as an experimental cost estimate, not a confirmed price for protecting Bitcoin in an actual quantum emergency.

Related coverage in the source also pointed to the broader threat. The Quantus founder has said crypto’s first quantum attack will look like an unexplained breach, while a separate Charles Edwards piece argued that a quantum roadmap would push Bitcoin much higher.