StarkWare Says It Completed First Bitcoin Transaction Built to Resist Quantum Attacks

StarkWare said it has completed the first Bitcoin transaction designed to defend against attacks from quantum computers.

The blockchain technology company told The Block on August 27 that the transaction demonstrated Bitcoin can achieve some protection on its existing network, countering the view that a network fork must come first to defend against quantum-computing threats.

The technology was developed by Avihu Levy, StarkWare's head of applications. It centers on a method called signature grinding, which is intended to prevent public key-related information from being exposed to quantum attacks while a Bitcoin transaction is waiting in the mempool.

A typical Bitcoin transaction sits in the mempool for a period before it is permanently recorded in a block. During that window, mathematical information could be exposed that a sufficiently powerful quantum computer could eventually use to forge a signature, StarkWare said.

Instead of using the first valid signature it generates, signature grinding repeatedly creates millions of signature candidates and selects one in a form that does not expose public key-related information to a quantum computer. The method is computationally demanding, however, and producing a single transaction can take hours.

The approach also has limitations because it is not a transaction format the Bitcoin network normally processes today. Regular nodes do not relay such transactions, so they must be sent directly to a miner willing to handle them rather than passing through the public mempool. The transaction was mined by Bitcoin miner MARA through its Slipstream service.

StarkWare did not describe the technology as a fundamental solution to Bitcoin's quantum-computing problem. Levy said Bitcoin should ultimately be upgraded at the protocol level to adopt a quantum-resistant architecture.

Chief Executive Officer Eli Ben-Sasson said the technique could serve as a safeguard until a permanent protocol upgrade is in place. “This breakthrough provides needed psychological reassurance,” he said. “It shows there is a lifeboat, not that everyone can relax. We need to build more lifeboats now.”