Debian has blocked non-reproducible packages from entering its testing branch — meaning new packages must produce identical binary outputs when rebuilt to prove they haven't been tampered with during compilation. This is a significant supply-chain security measure that makes it much harder for attackers to inject hidden malware into distributed binaries. The policy applies to Debian 14 (Forky), expected in 2027, and represents one of the strongest reproducibility mandates in any major Linux distribution.