Starkware researchers demonstrated that Bitcoin can support quantum-resistant transactions under existing consensus rules. On August 26, a transaction using the Quantum-Safe Bitcoin (QSB) construction developed by researcher Avihu Levy was mined on the Bitcoin mainnet without requiring soft forks or hard forks.
The transaction was processed through MARA Foundation's Slipstream service because its nonstandard format would not normally propagate through Bitcoin's public mempool. Starknet Foundation Vice President of Growth Damo announced the achievement at a Bitcoin Asia keynote, emphasizing that the milestone required no core protocol upgrades.
How QSB Works
Bitcoin's security currently relies on elliptic-curve cryptography, which could theoretically become vulnerable to sufficiently powerful quantum computers. The risk is particularly acute once a public key is exposed, as a quantum attacker could potentially derive the corresponding private key.
QSB addresses this by replacing signature-based security with hash-based protections and a technique called signature grinding. Most computational work occurs offchain before the transaction is broadcast. The mainnet test required hours of GPU computation and cost approximately $150 to $200.
Levy published the research in April, with Starkware engineer Tomer Giladi later implementing the working mainnet transaction. The work built on earlier research by BitVM creator Robin Linus and researcher Ethan Heilman.
Limitations and Future Direction
QSB remains opt-in and cannot protect funds whose public keys have already been exposed. Users must move coins into the protected construction before they face any quantum threat. The approach does not make Bitcoin itself quantum-resistant or recover lost coins.
Starkware CEO Eli Ben-Sasson stated that he continues to favor a protocol-level solution. "I still want Bitcoin to choose to do a soft fork, and I expect we will get one," he said. "What today's successful transaction offers bitcoin is a reassurance that holdings can be protected before that happens."
