On August 26, the StarkWare team behind the L2 solution Starknet achieved a historic breakthrough: the first transaction resistant to quantum computer attacks was conducted on the Bitcoin mainnet. Notably, this required no changes to the consensus rules of the first crypto asset. This is an important step demonstrating the ability to protect funds without waiting for a large-scale protocol upgrade.
The essence of the experiment and the QSB mechanism
The experiment was implemented within the framework of the Quantum Safe Bitcoin (QSB) concept, developed by StarkWare's Head of Product, Avihu Levy. The initiative was presented back in April as an emergency coin migration mechanism, and the company's engineer, Tomer Giladi, helped bring it to life. QSB is based on the "signature grinding" method, which relies on hash functions that are immune to quantum computing.
The essence of the method is that the system pre-selects, off-chain, a vast number of transaction variants until it finds one with the necessary cryptographic properties. The security of the final result is ensured by the difficulty of inverting the hash, rather than traditional elliptic curve cryptography. However, this approach has significant limitations: preparing a single operation can take several hours and cost hundreds of dollars in computational resources. The technical foundation was Binohash by Robin Linus, the creator of BitVM.
The transaction has already been included in a mainnet block. Due to its non-standard format, it is not relayed by regular nodes through the public mempool, so it was sent directly to the miner via the MARA Slipstream service.
Limitations and prospects
It is important to emphasize: this experiment does not make all of Bitcoin quantum-resistant. QSB allows protecting only individual coins by moving them to an output with additional protection, without changing the protocol itself. Moreover, the method is useless for coins whose public key has been previously exposed—an attacker would have enough time to analyze it before the protected transaction is sent.
StarkWare CEO Eli Ben-Sasson believes that the successful transaction gives Bitcoin confirmation that funds can be protected even before a soft fork, which he still considers the preferred long-term solution. The company is already implementing post-quantum protection in Starknet, presenting a three-stage plan to replace dependencies on elliptic curves.
My view: This is a brilliant example of engineering ingenuity that alleviates the urgency of the "quantum apocalypse" problem for Bitcoin. However, the high cost and slowness of QSB make it more of a safety net for large holders than a mass solution. The real battle for post-quantum security is still ahead, and it will be won at the protocol level.