I don't understand why "the app is now built reproducibly" implies "you need to uninstall it and then reinstall". What am I missing?
F-Droid
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
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android uses digital signatures as kind of a security measure. a digital signature is basically supposed to confirm that the apk was actually built by the developer, and most of the files in it were not tampered with.
besides being able to make permissions depend on it, you cannot install an app update that was signed with a different key to what you have already installed, because that basically means you are replacing it with a version that was built by someone else.
all apps are digitally signed. when an app becomes reproducibly built, from that point the app will be built by f-droid with their own digital signature.
also note that since google play has forced all developers to hand over their signing keys, when making app bundle based publishing mandatory, the security of this signature has been.. less useful
[…], from that point the app will be built by f-droid with their own digital signature.
This part of your comment is not quite true. One of the advantages of reproducible builds is that the app can be signed by the developer but fdroid can still verify that it has been built from the correct source code. You can check out the documentation here: https://f-droid.org/docs/Reproducible_Builds/
you're right, thanks for letting me know
This means that F-Droid can verify that an app is 100% free software while still using the original developer’s APK signatures.
then I don't understand it either why it can't be updated directly
Because there will be a signature mismatch. Apps built by F-Droid will use the F-Droid signature, reproducible apps will use the dev signature.
If an app doesn't support reproducible builds, the version you can download from F-Droid was built and signed by F-Droid, not by the dev
Why should I care to install another app? Fdroid updates apps if needed.
The update is for f-droid itself. It wont auto update itself to the new version.
If i read it correctly the uninstall/install part is for the F-Droid Build Status App and not for F-droid itself.
Ahh. I misunderstood.
Has there been any previous apps we need to install and uninstall?
I think the fdroid app will let you know if you need to do so when you try to update the app manually