Comment by gpm
1 day ago
That looks cool, which might just be the point of your comment, but I don't think it actually changes the argument here.
You still have to trust the app store to some extent. On first use, you're trusting f-droid to give you the copy of the app with appropriate signatures. Running in someone else's data-center still means you need to trust that data-center plus the people setting up the app store, instead of just the app store. It's just a breach of trust is less consequential since the attacker needs to catch the first install (of apps that even use that technology).
F-droid makes the most sense when shipped as the system appstore, along with pinned CA keychains as Calyxos did. Ideally f-droid was compiled from source and validated by the rom devs.
The F-droid app itself can then verify signatures from both third party developers and first party builds on an f-droid machine.
For all its faults (of which there are many) it is still a leaps and bounds better trust story than say Google Play. Developers can only publish code, and optional signatures, but not binaries.
Combine that with distributed reproducible builds with signed evidence validated by the app and you end up not having to trust anything but the f-droid app itself on your device.
None of this mitigates the fact that apriori you don't know if you're being served the same package manifest/packages as everyone else - and as such you don't know how many signatures any given package you are installing should have.
Yes, theoretically you can personally rebuild every package and check hashes or whatever, but that's preventative steps that no reasonable threat model assumes you are doing.