NTS: AUTHENTICATED TIME AT META

Summary from the TLDR InfoSec newsletter

Meta added Network Time Security (RFC 8915) to its public time service at nts.meta.com, so on-path attackers can no longer forge the clock that certificate, token, and replay-window checks rely on. Its servers hold no per-client state because each one derives the cookie-sealing key from a shared master secret and the Unix epoch day using HKDF-SHA256. NTS does not stop delay attacks or prevent an authenticated server from being simply wrong, and the stock Android and iOS time clients still sync over unauthenticated packets.