There is a naming problem here where "Nix" is often easily confused with the state management pieces (home-manager, NixOS, etc). The underlying Store abstraction provides the concepts of various kinds of addressing. This is independent of the Nix language and we are currently trying to expose each of these layers more directly so it can be re-used in other contexts.
The piece that might be of interest to you is the interaction between content-addressed and input-addressed content in light of build systems+software+compilers that are not bit-reproducible. There is also the bookkeeping to ensure auditability by third-parties; anyone else can run the same builds and expect the same outcome, or close enough that the differences become easy to find and report upstream (https://r13y.com/), but the system doesn't require bit-reproducibility from day1 because that would be impractical. Of course substituting from a cache is exact, made possible by the signatures.
Remote builds: https://nixos.org/manual/nix/stable/advanced-topics/distribu...
Signing (i'll amend my claim above to be only 1 decade). These are either signatures of a CA path, or for input-addressed things it can be seen as a claim by the signer that the producing build recipe (we call it "derivation") has this particular binary output.
- https://nixos.org/manual/nix/stable/command-ref/nix-store/ge...
- https://nixos.org/manual/nix/stable/advanced-topics/post-bui...
- https://nixos.org/manual/nix/stable/command-ref/conf-file.ht...
- https://nixos.org/manual/nix/stable/command-ref/conf-file.ht...
- example: see the Signatures line for an example that this this specific provenance produced this specific binary output: https://trusted-friendly-sesame.glitch.me/view.html?cache_ba... or https://cache.nixos.org/7ghhnlwla2mddkg7hgqa5v0sr8g5hga8.nar...