StarkWare Mines First Quantum-Safe Bitcoin Transaction

First quantum-protected transaction reaches Bitcoin mainnet

StarkWare says a quantum-safe Bitcoin transaction has been successfully mined on the Bitcoin mainnet. The achievement tests a way to protect funds from future quantum computing attacks without changing Bitcoin’s core rules.

StarkWare, the company behind the Ethereum layer-2 network Starknet, posted the update on Wednesday. The method allows Bitcoin holders to move coins into storage that a quantum computer cannot open.

What the research shows

The project is called Quantum-Safe Bitcoin, or QSB. StarkWare researcher Avihu Levy developed the method and published the research in April. Engineer Tomer Giladi then turned the proposal into a working transaction on the live network.

Bitcoin currently uses elliptic-curve cryptography to secure transactions. This system could theoretically be broken by a powerful quantum computer running Shor’s algorithm, which could derive private keys and steal funds. QSB adds a second lock based on hash functions instead, making it resistant to that specific threat.

The soft fork remains the goal

StarkWare emphasized that this transaction does not make Bitcoin quantum-safe as a whole network. It only protects the specific transaction it secures.

CEO Eli Ben-Sasson stated that StarkWare still favors a soft fork as the long-term defense. A soft fork can introduce new rules while remaining compatible with older software, whereas a hard fork introduces incompatible rules and can split the network.

“I still want Bitcoin to choose to do a soft fork and I expect we will get one,” Ben-Sasson said. He added that the successful transaction offers reassurance that holdings can be protected before such an upgrade happens.

Limitations and context

QSB uses a technique called “signature grinding.” This performs computational work off-chain to find a transaction hash that Bitcoin will accept as a valid signature.

However, the method has limits. It cannot protect addresses with already-exposed public keys and currently requires transactions to be sent directly to miners. StarkWare noted that roughly 7 million Bitcoin could be vulnerable due to exposed keys and address reuse, according to a June estimate by Coinbase’s quantum advisory council.

Why this matters

Ben-Sasson warned that the achievement should not be viewed as a message that Bitcoin is prepared for the quantum threat. Instead, he used the attention to urge the community to take the problem seriously and pursue soft forks to avoid future catastrophe.

Key details

• Company: StarkWare
• Project: Quantum-Safe Bitcoin (QSB)
• Lead Researcher: Avihu Levy
• Engineer: Tomer Giladi
• Vulnerable Bitcoin estimate: ~7 million (Coinbase, June)

Sources

• Decrypt