TL;DR:
- StarkWare cut the estimated compute cost of a quantum-safe Bitcoin transaction from $320 to roughly $67 in one week through an optimization challenge.
- Transaction pinning surpassed 820 million verified candidates per second, while subset selection exceeded 623 million, reducing the GPU-hours needed for construction.
- QSB remains an emergency option, not a complete Bitcoin quantum solution, because transactions are nonstandard, require miner submission and protect only coins with unexposed public keys.
StarkWare says optimization work has cut the estimated compute cost of a quantum-safe Bitcoin transaction from about $320 to roughly $67 in one week. In its official update, the company said the Quantum-Safe Bitcoin Optimization Challenge improved the brute-force search behind the design. The 79% reduction turns an expensive emergency mechanism into more practical for holders protecting large balances. The progress builds on StarkWare’s earlier quantum-resistant Bitcoin mainnet transaction, which required roughly 3,100 GPU-hours.
AI Optimization Pushes Quantum-Safe Bitcoin Costs Lower
The challenge focused on two bottlenecks: transaction pinning and subset selection. Pinning rose from 146.09 million to more than 820 million verified candidates per second on an RTX 4090, while subset selection improved from about 62 million to more than 623 million operations per second. Faster brute-force search reduces the GPU-hours needed to construct the transaction, which is why software optimization lowers the estimated cost. The effort forms part of StarkWare’s broader post-quantum roadmap across Bitcoin and Starknet.
The QSB construction places a hash where Bitcoin normally expects a signature, then repeatedly searches until the output satisfies Bitcoin’s DER-format requirements. Only around one in 70 trillion hash outputs matches the needed format, making computation the main expense. The network fee is not the costly part; the bill comes from offchain GPU work before reaching a miner. That distinction matters as researchers compare QSB with other post-quantum Bitcoin signature proposals.
The improvement does not make Bitcoin quantum-safe. QSB transactions remain nonstandard, cannot pass through the ordinary mempool and must be submitted directly to a miner. The design also protects only coins whose public keys have not been exposed. StarkWare still views a soft fork as the better long-term route for widespread quantum protection, with QSB serving as an emergency option under today’s consensus rules. The $67 figure is an estimate based on hardware assumptions and could change as competitors improve the code.
The challenge remains cryptographic migration. Bitcoin relies on elliptic-curve signatures vulnerable in theory to sufficiently capable quantum computers, while hash-based constructions degrade less severely. Lowering QSB’s cost shows that engineering optimization can materially improve defensive tools before protocol-level changes arrive. The result adds another data point to the industry’s post-quantum cryptography debate, where cost, signature size, compatibility and migration speed determine whether proposed defenses can scale.
