Quantum-Safe Bitcoin Cost Estimate Falls 82% To $59

StarkWare’s estimated computing cost for its Quantum-Safe Bitcoin method fell 82%, from about $320 during an August demonstration to $59 on Oct. 13. The estimate comes from a competition focused on protecting about 6.04 million BTC with publicly exposed keys.

StarkWare, Yukon Research and Eigen Labs organized the Quantum-Safe Bitcoin Optimization Challenge. Its latest benchmark recorded more than 1 billion verified candidates per second on an Nvidia RTX 4090 graphics card, up from about 146 million during the initial test. AI-assisted coding tools were used to speed up the computational searches.

The $59 figure is a hardware-based estimate from simulated GPU workloads, not the cost of a completed production transaction. Bitcoin network fees are excluded, and some stages of the calculation still rely on provisional assumptions. StarkWare set a target of bringing the computing cost below $10.

Quantum-Safe Bitcoin, or QSB, uses hash-based cryptography and a computational puzzle to protect specially prepared Bitcoin holdings from attacks on conventional digital signatures. Holders can complete the calculations off-chain before spending the coins, allowing the method to operate under Bitcoin’s current consensus rules.

QSB is intended as an interim measure while developers consider broader changes to Bitcoin’s cryptographic system. It can protect eligible coins whose public keys remain hidden until the coins are transferred into specially constructed outputs.

A Glassnode study estimated that about 6.04 million BTC, or 30.2% of Bitcoin’s issued supply at the time, had public keys exposed on-chain. The amount included about 1.92 million BTC linked to address structures that reveal public keys and 4.12 million BTC exposed through address reuse or previous spending.

A sufficiently powerful quantum computer could potentially use exposed public keys to derive private keys and take control of associated coins. In March, Google Quantum AI researchers estimated that future quantum computers could break the elliptic-curve cryptography used by Bitcoin in minutes with fewer than 500,000 physical qubits under specified hardware conditions. No publicly demonstrated quantum computer currently has those capabilities.

QSB transactions comply with Bitcoin’s consensus rules, but ordinary network relay policies reject them. Users must submit the transactions directly to miners willing to process them. Bitcoin miner MARA provided that route through its Slipstream service during the August demonstration.

StarkWare continues to support a broader Bitcoin protocol upgrade for long-term protection. Researchers still need to test the latest cost estimates in complete transactions and establish reliable access to miners before QSB can be used as a fallback.