On August 26, developers from StarkWare, the company behind the L2 solution Starknet, successfully conducted the first quantum-safe transaction on the Bitcoin mainnet. This achievement did not require any changes to the consensus rules.
Quantum-safe Bitcoin, mined on mainnet, Today.
Designed by @avihu28 - the first ever quantum-safe Bitcoin transaction was built in collaboration with @MARAFoundation_ and our own @giladi_tom85141.
Every chain faces the same quantum deadline. Today we took a huge step to move…
— StarkWare 🥷 (@StarkWareLtd) August 26, 2026
This experiment was part of the Quantum Safe Bitcoin (QSB) initiative, conceived as an emergency measure for migrating coins until full post-quantum protocol protection is available. The concept was introduced in April by StarkWare's product director, Avihu Levi, with engineering support from Tomer Giladi.
Understanding QSB
Levi's initiative enhances Bitcoin's existing security with an additional layer based on hash functions that are resilient against quantum computer threats.
The signature grinding technique operates by generating numerous potential signatures before finding one that meets the desired cryptographic properties. Most computations occur off-chain, while the security of the final outcome relies primarily on the difficulty of inverting the hash.
Currently, this method is both costly and slow, with a single operation taking several hours and costing hundreds of dollars in computational resources. The development is based on Binohash, created by BitVM's Robin Linus.
The transaction has already been included in a Bitcoin block. However, due to its non-standard format, regular nodes do not relay such messages through the public mempool, necessitating direct transmission to the miner via the MARA Slipstream service.
Bitcoin Still Not Quantum-Safe
StarkWare clarified that this experiment does not render the entire network immune to quantum attacks. The QSB allows for the transfer of specific coins with added protection without altering Bitcoin's fundamental protocol.
This method will not safeguard coins whose public keys have been previously exposed. In such scenarios, a potential attacker might have sufficient time to analyze the key before the protected transaction is sent.
Both Levi and StarkWare's CEO Eli Ben-Sasson continue to view this upgrade as the preferred long-term solution.
“Avihu took this on in his spare time, out of personal interest, and has now demonstrated that Bitcoin is not going to expire. I still want Bitcoin to opt for a soft fork and hope that it will happen. The successful transaction gives Bitcoin proof that funds can be protected even before that time,” said Ben-Sasson.
He added that the experiment shows owners will have an additional means of securing their assets prior to any such upgrade.
StarkWare is already implementing post-quantum protection in Starknet. In June, the company unveiled a three-phase plan to replace remaining dependencies on elliptic curves and to migrate existing contracts.
It is worth noting that in late July, Cardano founder Charles Hoskinson suggested that Bitcoin could lose its leadership due to quantum threats.