Bitcoin’s new quantum defenses, 18.9M SOL cancelled: Hodler’s Digest

Bitcoin embraces post quantum future

Despite considerable skepticism among Bitcoiners about how close the quantum threat to Bitcoin actually is, two stories this week highlighted the progress being made toward upgrading the blockchain and protecting outputs from attack.

StarkWare researcher Avihu Levy tested an experimental quantum-resistant transaction on the Bitcoin mainnet that protects it during the brief period when public keys are exposed in the mempool.

Onchain data shows that StarkWSare spent a 10,000-satoshi output protected by Levy’s Quantum Safe Bitcoin (QSB) scheme. It combines hash-based one-time signatures with computational searches that bind an authorization to a specific transaction. While it works, it’s more of a last resort than a practical measure, as each transaction takes hours and costs between $150 to $200.

There’s also been progress on long term upgrades to protect every transaction. On August 27, Blockstream researchers published a Bitcoin Improvement Proposal to upgrade Bitcoin with the SHRINCS signature scheme. The researchers slimmed down a huge, hash based post quantum signature by about 13.23 times — an impressive effort, but the SHRINCS signature is still at least nine times larger than Bitcoin’s existing signatures and comes with a bunch of trade offs.