QSB

Can Bitcoin coins be made quantum-safe without a soft fork?

Yes, one coin at a time. QSB adds hash-based protection to a Bitcoin spend under today's rules, but it does not make Bitcoin, as a whole, quantum-safe.

to prepare one transaction: $59
since the first transaction: −81.5%
promoted challenge improvements: 86
changes to Bitcoin’s rules: 0

Leaderboard data checked 27 Oct 2026. Figures refresh automatically on visits, about every 15 minutes. The QSB challenge is closed.

What is QSB, and how does it work?

Quantum-Safe Bitcoin (QSB) is a way to spend bitcoin that a quantum computer cannot forge, using only the rules Bitcoin has today. StarkWare researcher Avihu Levy published the design on 9 April 2026, building on Robin Linus's Binohash.

Lock the coins in a QSB output. It adds a second lock beside the usual signature, built on hash functions instead of elliptic curves.
Search before spending. The spender runs a large GPU search offchain to solve a hash puzzle that binds the spend to one exact transaction.
Send it straight to a miner. The transaction is larger than normal relay rules allow, so it goes to a miner directly. The first was mined on 26 Aug 2026.

QSB does not make Bitcoin as a whole quantum-safe or rescue coins whose public keys are already exposed, and each spend still needs about $59 of GPU compute and a direct path to a miner. StarkWare sees a soft fork as the better long-term answer.

Cost over time

GPU compute to prepare one transaction

Modelled estimates in USD

$320
26 Aug 2026First QSB transaction
$320
16 Sep 2026Challenge launched
$67
23 Sep 202662 promoted improvements reported
$59
27 Oct 2026Dashboard check · challenge closed

View the cost ledger and sources

QSB preparation cost ledger · newest first
Date	GPU cost (USD)	Change vs first	Record	Source
27 Oct 2026	$59	-81.5%	Dashboard check · challenge closed	Source ↗
23 Sep 2026	$67	-79.1%	62 promoted improvements reported	Source ↗
16 Sep 2026	$320	0.0%	Challenge launched	Source ↗
26 Aug 2026	$320	0.0%	First QSB transaction	Source ↗

Which coins QSB protects

Protection depends on when the key is exposed

Public key not yet exposedMove coins into QSBHash-based protection

Public key already exposedIncluding reused addresses and early P2PK outputs, such as coins attributed to SatoshiQSB cannot rescue these coins

QSB cannot protect already-exposed public keys. Early pay-to-public-key (P2PK) outputs expose the key directly, including coins attributed to Satoshi.

QSB vs a soft fork

Comparison · QSB and the BIP-360 proposal
	QSB	Soft fork · BIP-360
Consensus change	None	Required
Available today	Yes, since the first mainnet transaction on 26 Aug 2026	No. BIP-360 is a proposal and has not been activated
Who is protected	Coins moved into QSB before their key is exposed	Holders who move to P2MR outputs: protection against long-exposure attacks. Short-exposure protection needs additional post-quantum signatures.
Cost to use	About $59 modelled GPU compute per transaction, plus fees	Fees depend on the spending script and transaction size.
How it is sent	Directly to a miner; nonstandard for public relay	Would need compatible wallets and nodes after activation
StarkWare’s view	An option that works today	The better long-term answer

BIP-360 targets long-exposure attacks; it does not itself add post-quantum signatures. Read the proposal ↗

Credits

Avihu Levy published the QSB design on 9 April 2026. StarkWare, Yukon Research and Eigen Labs organized the optimization challenge.