Bitcoin Mainnet Confirms Quantum-Resistant Transaction, But Millions Remain Exposed

Bitcoin has confirmed a quantum-resistant transaction on its mainnet using its existing consensus rules. This demonstrates that some holders can migrate funds away from future quantum risk without waiting for a protocol upgrade. The August 26 transaction used a construction developed by StarkWare researcher Avihu Levy, which shifts the critical spending condition away from elliptic-curve signatures and toward hash-based security.

The test was submitted directly to Bitcoin miner MARA through its Slipstream service and included in block 964,199. StarkWare described this 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, Eli Ben-Sasson, StarkWare Chief Executive, emphasized that the workaround does not make Bitcoin quantum-safe. He warned that broader soft-fork solutions are still needed to protect the network at scale. The test should be seen as evidence that workable approaches exist, but not as proof that Bitcoin is already prepared for quantum computing.

The Quantum-Safe Bitcoin construction uses a delay in revealing public keys to move eligible coins into a hash-based spending condition. This computation takes place before the transaction is broadcast, shifting the security assumption away from elliptic-curve cryptography and toward the difficulty of reversing hash functions.