# AI Agents Are Racing to Make Quantum-Safe Bitcoin Cheap—And Winning > Source: > Published: 2026-09-26 15:01:05+00:00 #### In brief - StarkWare said the estimated cost of building a quantum-safe Bitcoin transaction fell from about $320 to roughly $67 in a week, as solvers in its Quantum-Safe Bitcoin Optimization Challenge optimized the brute-force search that runs on a user's own GPU before hitting the chain. - The leading records were held by developers running AI models, including Anthropic's Opus 5 and Fable 5.1, with OpenAI's GPT-6 Astra, Grok 4.6 and Kimi close behind. - StarkWare cautioned the $67 is an estimate, not a price, and that the work doesn't make Bitcoin quantum-safe on its own—it still favors a soft fork long-term. The price of building a quantum-resistant Bitcoin transaction has plunged nearly 80% in a single week, after developers and AI models competed to optimize the code behind it. According to StarkWare, which ran the competition alongside Yukon Research and Eigen Labs, the [estimated cost of constructing such a transaction](https://starkware.co/blog/ai-research-competition-cut-quantum-safe-bitcoin-costs-by-79-in-a-week/) fell from about $320 to roughly $67 in GPU compute. The figure comes from the dashboard of the Quantum-Safe Bitcoin Optimization Challenge, an open contest launched to see how far outside solvers could push the number down. The [first quantum-safe Bitcoin transaction was mined](https://decrypt.co/376767/bitcoin-quantum-safe-transaction-starkware) on mainnet last month, a construction StarkWare developed to protect coins without requiring a network-wide fork. That initial transaction took roughly 3,100 GPU-hours and cost around $320 to build. One week of open competition cut most of that away. The savings come from raw speed. The expensive part of the process is a brute-force search that happens on a user's own hardware before anything reaches the blockchain, which is why it shows up as a GPU bill rather than a Bitcoin fee. The construction slots a hash where Bitcoin expects a signature, and because only about one in 70 trillion hash outputs takes the required shape, finding a valid one means hashing inputs over and over until one fits. Faster code means fewer GPU-hours for the same result. Solvers made dramatic progress. One core benchmark jumped from 146 million verified candidates per second to over 820 million on a standard RTX 4090, with 62 improvements promoted across two tracks. Notably, the leading records were held by developers running AI models, with StarkWare citing Anthropic's Opus 5 and Fable 5.1 at the top and OpenAI's GPT-6 Astra, Grok 4.6, and Kimi close behind. StarkWare was careful to temper expectations. The $67 is an estimate under stated hardware assumptions, not a market price, and it shifts each time a solver beats the record. The company stressed the effort doesn't make [Bitcoin quantum-safe on its own](https://decrypt.co/374753/bitcoin-quantum-threat-ibm-claims-trusted-quantum-advantage): the transactions are nonstandard and must be sent directly to a miner, and the construction only shields coins whose public key hasn't already been exposed. StarkWare maintains that a [soft fork remains the better long-term fix](https://decrypt.co/364092/quantum-safe-bitcoin-transactions-without-fork). The work lands amid intensifying focus on Bitcoin's exposure to "[Q-Day](https://decrypt.co/resources/what-q-day-quantum-threat-bitcoin-explained)," the hypothetical point when quantum computers could break the elliptic-curve cryptography securing wallets. Firms including [Coinbase are already drafting post-quantum custody playbooks](https://decrypt.co/379000/coinbase-playbook-post-quantum-bitcoin-custody).