Bitcoin now has a quantum computing escape route, but 7 million BTC may still be exposed

Bitcoin has confirmed a quantum-resistant transaction on mainnet using its existing consensus rules, showing that some holders could migrate funds away from future quantum risk without waiting for a protocol upgrade.

The Aug. 26 transaction used a construction developed by StarkWare researcher Avihu Levy that shifts the critical spending condition away from elliptic-curve signatures and toward hash-based security. It was included in block 964,199 after being submitted directly to Bitcoin miner MARA through its Slipstream service.

StarkWare described the transaction as the first quantum-safe spend on Bitcoin mainnet. Earlier experiments explored post-quantum approaches in Bitcoin Script and on Blockstream’s Liquid sidechain, but this test showed that Bitcoin itself could accept a hash-based spending path without changing consensus rules.

However, the workaround does not make Bitcoin quantum-safe.

StarkWare Chief Executive Eli Ben-Sasson said the test should not be interpreted as evidence that Bitcoin is already prepared for quantum computing. He argued that broader soft-fork solutions are still needed to protect the network at scale.

“A quantum-safe Bitcoin tx on mainnet” proves that workable approaches exist, Ben-Sasson said, while warning that the main task remains building a migration path before quantum hardware becomes capable of threatening exposed keys.