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Bitcoin’s ‘last resort’ quantum-safe solution just got 79% cheaper: StarkWare
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StarkWare says an experimental quantum-resistant way to prepare Bitcoin transactions now costs an estimated $66 to $67, a roughly 79% reduction from the first mainnet attempt. The improvement followed a weeklong optimization effort and could make an emergency defense more practical for holders with substantial balances. It matters because a sufficiently powerful quantum computer could threaten the signatures protecting Bitcoin, although the new figures have so far appeared only in benchmarks.
The Quantum-Safe Bitcoin design was outlined in April by StarkWare researcher Avihu Levy as a hash-based defense that does not require changes to Bitcoin’s consensus rules. Levy positioned it as a last-resort measure because of its cost, complexity and limited applicability. The approach is therefore not being presented as a routine feature for every transfer or a replacement for a network-wide security upgrade. StarkWare continues to favor a soft fork as Bitcoin’s long-term quantum-protection strategy.
Bitcoin’s first QSB transaction was mined and confirmed on August 26, according to StarkWare. Its preparation required about 3,100 GPU-hours on roughly 100 GPUs, producing an estimated compute cost of approximately $320, excluding Bitcoin network fees. Engineering work came from Tomer Giladi, while the transaction was submitted directly through MARA’s Slipstream service. That demonstration provided a real-world reference point for judging subsequent software improvements.
StarkWare, Yukon Research and Eigen Labs then launched the Quantum-Safe Bitcoin Optimization Challenge on September 16. Developers, researchers and AI agents were invited to improve the transaction-building software’s speed and efficiency. StarkWare reported 62 accepted improvements across the two computational tasks required to prepare a QSB transaction. Those changes lowered the estimated cost by about 79% in benchmark tests, according to the company’s September 23 update.
Bitcoin relies on elliptic-curve digital signatures, and a powerful enough quantum computer could undermine the security of exposed public keys by enabling attackers to forge signatures and steal associated coins. QSB adds hash-based protection designed to reduce that exposure without changing consensus. Its difficult part is computationally preparing the protective transaction, rather than mining the transaction once it has been built. The benchmark reductions concern that preparation stage and should not be confused with the cost of mining a Bitcoin transaction.
StarkWare argued that a construction costing a few hundred dollars per transaction remained a demonstration, while one costing $67 was closer to something a holder with a large, unexposed balance might use in an emergency. The result could lower the barrier to testing and deploying the defense, particularly for high-value wallets. For the broader market, however, $66 remains a substantial emergency expense and says little about the cost of protecting every holder. Nor has the benchmark result yet been demonstrated in a new mainnet transaction.
Further work must validate the benchmark in a new mainnet transaction and clarify the hardware, pricing and implementation assumptions behind the $66 estimate. Researchers will also have to assess whether the method is practical beyond wallets with large, unexposed balances. That limitation reinforces StarkWare’s preference for a soft fork as the long-term answer for broad quantum protection. The 79% reduction is therefore a promising engineering milestone, not a completed network upgrade or a resolution of Bitcoin’s quantum-security debate.
