StarkWare tests quantum-resistant Bitcoin transaction on mainnet
StarkWare has executed the first quantum-resistant Bitcoin transaction on mainnet, confirming block 964,199 on Wednesday. As StarkWare tests quantum-resistant Bitcoin spending without a fork, Avihu Levy's Quantum Safe Bitcoin scheme spent a 10,000-satoshi output via MARA Pool. The milestone shows existing rules can handle post-quantum authorization, though the test cost up to $200 and required direct miner submission.
Key Takeaways
- StarkWare confirmed a quantum-resistant Bitcoin mainnet transaction in block 964,199, mined by MARA Pool via Slipstream.
- Avihu Levy's QSB scheme combines hash-based one-time signatures with computation that binds spending to a specific transaction.
- The test cost an estimated $150 to $200 in GPU work and took hours of computation to generate.
- QSB transactions are classified as nonstandard and cannot propagate through ordinary Bitcoin nodes before confirmation.
- Developers are also pursuing protocol-level upgrades, including Blockstream's newly published SHRINCS BIP and the proposed BIP-360 soft fork.
What Did StarkWare Test on Bitcoin Mainnet?
StarkWare researcher Avihu Levy tested an experimental quantum-resistant transaction on Bitcoin mainnet, which the company described as the first transaction of its kind. Onchain data shows the transaction spent a 10,000-satoshi output protected by Levy's Quantum Safe Bitcoin scheme.
MARA Pool mined the block after receiving the transaction through its Slipstream service. Levy's paper and code repository said QSB combines hash-based one-time signatures with computational searches that bind authorization to a specific transaction, intended to prevent forgery even if a quantum computer breaks Bitcoin's elliptic-curve cryptography.
The demonstration moves Levy's April proposal from theory to an onchain test, showing Bitcoin's existing consensus rules can accommodate quantum-resistant spending without a protocol change. For broader fintech and crypto alerts, the timing aligns with rising industry attention to post-quantum security.
Why Does Quantum Computing Threaten Bitcoin?
In March, Google researchers estimated that a sufficiently capable quantum computer could theoretically derive a Bitcoin private key nine to 12 minutes after its public key becomes visible. Google said that could allow an attacker to replace a pending transaction during Bitcoin's confirmation window.
Scientists broadly agree that advanced quantum computers could reverse-engineer private keys from public keys, undermining Bitcoin's security. Levy introduced QSB in April as a last-resort measure rather than a replacement for protocol-level protections, estimating at the time that generating a transaction would require between $75 and $150 in GPU computation.
How Does QSB Compare to SHRINCS and BIP-360?
QSB applies to individual Bitcoin transactions rather than upgrading cryptography across the network. StarkWare CEO Eli Ben-Sasson said a soft fork should happen and that QSB provides a safety net while protocol-level protections are developed.
Bitcoin developers are separately considering proposals including BIP-360, a proposed soft fork that would introduce a Pay-to-Merkle-Root output type while removing Taproot's quantum-vulnerable key-path spend. On the same day, Blockstream published a Bitcoin Improvement Proposal for SHRINCS, a hash-based post-quantum signature scheme that Jonas Nick called the first concrete proposal designed specifically for Bitcoin.
SHRINCS has signed real transactions on Blockstream's Liquid sidechain and could let Bitcoin run at roughly 3 transactions per second, but its BIP warns that a security proof remains unfinished and the scheme introduces stateful wallet complexity.
What Are the Limits of Quantum-Resistant Bitcoin Today?
StarkWare spokesperson Nathan Jeffay told Cointelegraph the completed transaction cost low hundreds of dollars, estimating around $150 to $200. StarkWare's release said the process took hours of computation, above Levy's earlier $75-to-$150 estimate.
Levy's repository classifies QSB transactions as nonstandard under Bitcoin Core's default relay policies. Ordinary nodes therefore would not propagate the transaction before confirmation, requiring direct submission through MARA's Slipstream service.
Ben-Sasson emphasized that QSB is a safety net, not a network-wide fix. Between QSB, SHRINCS, BIP-360, and other proposals, the engineering options are expanding quickly, but Bitcoin still lacks a clear governance path for choosing among them before quantum threats materialize.