Google’s Quantum Advance Exposes Bitcoin’s Hidden Upgrade Cost

The hardest part of protecting Bitcoin from quantum computers may not be finding a secure replacement for its signatures. It may be fitting that replacement into a blockchain where every byte competes for limited capacity. A standard Taproot key-path signature occupies 64 bytes. An illustrative replacement using NIST’s ML-DSA-44 would require a 2,420-byte signature and potentially another 1,312 bytes to reveal the public key. Combined, that is 3,732 bytes of cryptographic data, roughly 58 times the original signature payload. Google’s latest quantum computing breakthrough makes this trade-off more relevant. On October 15, the company reported that its Willow processor had reduced errors in a specialized quantum operation by approximately 40 times, achieving 99.99% fidelity through a technique called magic state cultivation.

First reported by Crypto News Flash. This page is a short excerpt; the full text is theirs.