Quantum-Safe Bitcoin Compute Estimate Falls 82% to $59 as Reach Stays Limited

The estimated GPU-computation cost of preparing a Quantum-Safe Bitcoin (QSB) transaction has fallen to $59 from about $320, reducing the modeled cost by approximately 82% while leaving miner access and public-key exposure as major practical constraints.

The $59 figure is based on simulated workloads rather than a completed Bitcoin (BTC) mainnet transaction at that cost. QSB transactions remain nonstandard and generally require direct submission to a miner instead of ordinary relay through Bitcoin’s mempool.

StarkWare, Yukon Research and Eigen Labs launched the Quantum-Safe Bitcoin Optimization Challenge on Sept. 16. StarkWare is offering $20,000 in prizes, with an additional prize from Yukon Research, across two separate workloads: transaction pinning and subset selection.

The first QSB transaction was mined on Bitcoin’s mainnet Aug. 26 after about 3,100 GPU-hours, at an estimated computation cost of roughly $320. That estimate excluded the transaction fee.

The estimated cost was $59 as of Oct. 13. The underlying model uses measurements from a simulated fleet of 100 RTX 3090 GPUs, while later gains on RTX 4090 hardware extend beyond the measurement cutoff. A pinning-track result reached 1,036,462,054 verified candidates per second on an RTX 4090 at 1:20 a.m. ET (5:20 a.m. UTC) on Oct. 5.

Pinning and subset selection are separate workloads, and submitted results are independently re-derived by a CPU verifier. Results from the RTX 3090-based cost model and the RTX 4090 benchmark are therefore not directly interchangeable.

The reduction follows earlier optimization work that lowered the estimated cost to $67. QSB uses hash-based protection under Bitcoin’s existing consensus rules and does not require a soft fork or protocol upgrade.

QSB can protect eligible coins whose public keys have not already been exposed, but it does not retroactively protect coins with visible public keys. The first mainnet transaction used MARA’s Slipstream service to reach a miner because QSB transactions do not normally pass through Bitcoin’s mempool.

Bitcoin’s conventional ECDSA and Schnorr signature systems rely on elliptic-curve cryptography. A sufficiently capable quantum computer using Shor’s algorithm could theoretically derive private keys from exposed public keys. Most Bitcoin outputs initially conceal public keys behind hashes, but keys can become visible through address reuse, previous spending or script types that reveal them directly.

An estimated 6.04 million BTC, or 30.2% of issued supply, was classified as publicly exposed as of May 20 under an at-rest exposure methodology. The estimate included 1.92 million BTC of structural exposure and 4.12 million BTC of operational exposure. It does not establish the amount as current on Oct. 13 or show that all exposed holdings can be moved into QSB-protected outputs.

A March 2026 estimate found that breaking 256-bit elliptic-curve cryptography could require fewer than 500,000 physical qubits under specified superconducting-hardware assumptions. That is a theoretical resource estimate, not a demonstration of a working Bitcoin-breaking quantum computer.

QSB remains an interim mechanism requiring substantial off-chain computation, nonstandard transaction handling and miner cooperation. Broader protection would require changes to Bitcoin’s consensus rules.