Nix packages are blindly and automatically signed by a single private key last I reviewed it. Bribe or compromise one person and the entire model fails. There is good reason to do this too given that many major blockchain projects use it for builds. Hundreds of millions to be made by one that impersonates the right maintainer before the right software release.

Also no signed commits or signed authorship means someone with Github access can just fake history and inject whatever they want after code reviews are completed, which will then be blindly and automatically signed.

Some of the people with write access to the nixpgs repo even have SMS recovery enabled on their github recovery email accounts. One sim swap to compromise all nix users. I will not call them out, but go try to do a email password reset on recent committers for yourself. A malicious github employee could also of course do whatever they want to an unsigned repo. Or a well placed BGP attack. Lots of options. It is hard to prevent such things, but author commit signing would mitigate the risk and can be enforced.

I made my case for this to the nix team but in the end it was concluded people would stop maintaining packages if they had to do the bare minimum like commit signing or hardware 2FA. https://github.com/NixOS/rfcs/pull/34

All this is fine, but it means effectively a decision was made for NixOS to be a hobby distro not suitable for any targeted applications or individuals. It really sucks, because I love everything else about nix design.

Instead I am forced to bootstrap high security applications using arch and debian toolchains which are worse than nix in every way but supply chain integrity given that all authors directly sign package sources with their personal well verified keys. They have a ton of other security and even their own supply chain problems but they at least can survive phishing, a malicious mirror, or a sim swap. It is a low bar nix sadly does not meet.