- StarkWare said researcher Avihu Levy has carried out an experimental quantum-resistant Bitcoin transaction on the mainnet. The transaction used a 10,000-satoshi output from block 964,199, all without modifying Bitcoin’s existing consensus rules.
- StarkWare called the test the first transaction of its type. MARA Pool mined the transaction after receiving it directly through Slipstream, because Bitcoin’s regular nodes would not relay its nonstandard format across the public mempool.
- StarkWare spokesperson Nathan Jeffay said the transaction required roughly $150 to $200 worth of computation. The company added that the process took several hours, highlighting that the technique can protect individual Bitcoin outputs today but remains costly in terms of both computing resources and operations.
How StarkWare’s Quantum-Safe Bitcoin System Works
- Levy introduced the Quantum-Safe Bitcoin (QSB) concept in April. The system combines hash-based one-time signatures with computational searches to tie authorization to a particular transaction. Its goal is to stop unauthorized spending even if future quantum computers can break the elliptic-curve cryptography currently used by Bitcoin.
- Google researchers estimated in March that a powerful enough quantum computer could theoretically extract a Bitcoin private key within nine to 12 minutes once its public key becomes visible. If that becomes possible, an attacker could potentially interfere with a transaction before it is fully confirmed.
- QSB is designed to protect individual Bitcoin transactions rather than replace the network’s cryptographic infrastructure. It allows coins to be transferred into specially secured outputs without requiring a protocol upgrade. However, coins linked to public keys that have already been exposed would not gain protection until they are moved.
- The approach also faces a practical limitation because its transaction format falls outside Bitcoin Core’s standard relay policy. Ordinary nodes will not broadcast it before confirmation, so transactions must be sent directly to a participating miner through infrastructure such as MARA’s Slipstream. This means users need to prepare the transaction in advance and have access to a cooperating miner.
- StarkWare CEO Eli Ben-Sasson said QSB could provide an additional layer of security while developers pursue permanent protocol-level solutions. Rather than changing Bitcoin’s underlying cryptography, the system offers a way to introduce quantum-resistant spending within the current rules.
- Meanwhile, Bitcoin developers are examining alternatives such as BIP-360, a proposed soft fork that would introduce Pay-to-Merkle-Root outputs and remove Taproot’s quantum-vulnerable key-path spending. Such a change would require coordination throughout the network and formal activation.
- QSB takes a different approach by operating without waiting for a consensus upgrade. StarkWare’s mainnet experiment shows that Bitcoin’s current rules can support a limited form of quantum-resistant spending, although wider protection will likely depend on future protocol changes.
