Hash, Cash, & Quantum Smash: StarkWare's QSB Challenge Cuts $BTC's Quantum Bill by 79% 🧮

The estimated compute cost of building a quantum-resistant $BTC transaction has fallen to roughly $67 from about $320, a drop of nearly 79% achieved in a week of open competition, according to StarkWare. The figure, drawn from the dashboard of the Quantum-Safe Bitcoin Optimization Challenge run by StarkWare with Yukon Research and Eigen Labs, marks the latest benchmark in a race to make hash-based protection against future quantum attacks practical for Bitcoin holders without changing the network's consensus rules. "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, adding that the dashboard now shows an estimated cost of $66.

The reduction stems from improvements to the GPU-heavy brute-force search required before any transaction reaches the blockchain, a process that only succeeds when a hashed output meets a roughly one-in-70-trillion target. Solvers pushed one core benchmark from 146 million verified candidates per second to over 820 million on a standard RTX 4090, with 62 accepted improvements promoted across two computational tracks. StarkWare noted that the leading records were held by developers running AI models, citing Anthropic's Opus 5 and Fable 5.1 at the top, followed by OpenAI's GPT-6 Astra, Grok 4.6 and Kimi.

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

StarkWare stressed that the $67 figure is an estimate under stated hardware assumptions, not a market price, and shifts each time a solver beats the record. The company reiterated that QSB transactions are nonstandard, must be sent directly to a miner, and only shield coins whose public keys have not already been exposed. StarkWare maintains that a soft fork remains the better long-term answer for broad quantum protection on $BTC, even as firms including Coinbase draft post-quantum custody playbooks ahead of the hypothetical "Q-Day" when quantum computers could break the elliptic-curve cryptography securing wallets.