https://winternitz.tech/notes/Post-quantum cryptography, crypto custody and offensive security by Kyeson Blake Utley.en-ushttps://winternitz.tech/notes/harvest-now-decrypt-later/https://winternitz.tech/notes/harvest-now-decrypt-later/Why data encrypted today can be read by tomorrow's quantum computers, how to use Mosca's inequality to tell whether you're already late, and what to fix first.hello@winternitz.tech (Kyeson Blake Utley)Sat, 17 Oct 2026 12:00:00 +0000https://winternitz.tech/notes/stateful-signatures-and-backups/https://winternitz.tech/notes/stateful-signatures-and-backups/LMS and XMSS are standardized, quantum-safe and fast. They also break catastrophically if a one-time key is used twice. Here's how ordinary operations cause that, and how to prevent it.hello@winternitz.tech (Kyeson Blake Utley)Sat, 17 Oct 2026 11:00:00 +0000https://winternitz.tech/notes/q-day-and-crypto-custody/https://winternitz.tech/notes/q-day-and-crypto-custody/Bitcoin and Ethereum rely on elliptic-curve signatures that a large quantum computer could break. Which coins are exposed first, why address reuse matters, and what custodians can do now.hello@winternitz.tech (Kyeson Blake Utley)Sat, 17 Oct 2026 10:00:00 +0000