# Stacks Tests Post-Quantum Signing in Mainnet sBTC Transfer By Simon Yoon Canonical URL: https://www.tokenpost.com/news/technology/55029 Published: 2026-11-12T06:34:29.000Z Updated: 2026-11-12T06:34:29.000Z Section: Technology > A vault checked a Lamport signature before releasing sBTC in the mainnet test. Stacks completed a mainnet sBTC vault withdrawal using a Lamport one-time signature to authorize release, testing post-quantum signing in the vault flow. The test did not upgrade ordinary sBTC wallets or the Bitcoin backing the token. The test touches a broader design issue for Bitcoin. Bitcoin uses ECDSA and Schnorr signatures, which a sufficiently powerful quantum computer could threaten. Post-quantum alternatives may require larger signatures, adding transaction data. Stacks co-founder Muneeb Ali has estimated that larger signatures could cut Bitcoin block capacity by as much as 10-fold, a tradeoff described in [Ali’s estimate of the capacity impact](). ## Links in this article - [Ali’s estimate of the capacity impact](https://www.tokenpost.com/news/technology/40654)