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@ -85,7 +85,7 @@ While it may seem bothersome, it's a necessity to keep the **app ecosystem moder
## 4. General lack of good practices
The F-Droid client allows multiple repositories to coexist within the same app. Many of the issues highlighted above were focused on the main official repository which most of the F-Droid users will use anyway. However, having **other repositories in a single app also violates the security model of Android** which was not designed for this at all. The OS expects you to trust **an app repository as a single source** of apps, yet F-Droid isn't that by design as it mixes several repositories in one single app. This is important because the OS management APIs are not meant for this and see F-Droid as a single source, so you're trusting the app client to not mess up far more than you should. It is also worth noting the repository metadata format isn't properly signed by lacking whole-file signing and key rotation.
As a matter of fact, the [new unattended update API](https://developer.android.com/reference/android/Manifest.permission#UPDATE_PACKAGES_WITHOUT_USER_ACTION) added in API level 31 (Android 12) that allows seamless app updates for app repositories without [privileged access](https://f-droid.org/en/packages/org.fdroid.fdroid.privileged/) to the system (such an approach is not compatible with the security model) won't work with F-Droid. It should be mentioned that [Droid-ify](https://github.com/Iamlooker/Droid-ify/issues/20) is trying to figure out a way to make it work, although the underlying issues about the F-Droid infrastructure largely remain. Indeed, this secure API allowing for unprivileged unattended updates not only requires for the app repository client to target API level 31, but the apps to be updated also have to at least target API level 29.
As a matter of fact, the [new unattended update API](https://developer.android.com/reference/android/Manifest.permission#UPDATE_PACKAGES_WITHOUT_USER_ACTION) added in API level 31 (Android 12) that allows seamless app updates for app repositories without [privileged access](https://f-droid.org/en/packages/org.fdroid.fdroid.privileged/) to the system (such an approach is not compatible with the security model) won't work with F-Droid. It should be mentioned that the aforementioned third-party client [Droid-ify](https://github.com/Iamlooker/Droid-ify/issues/20) is trying to figure out a way to make it work, although the underlying issues about the F-Droid infrastructure largely remain. Indeed, this secure API allowing for unprivileged unattended updates not only requires for the app repository client to target API level 31, but the apps to be updated also have to at least target API level 29.
Their client also lacks **TLS certificate pinning**, unlike Play Store which does that for all connections to Google. Certificate pinning is a way for apps to increase the security of their connection to services [by providing a set of public key hashes](https://developer.android.com/training/articles/security-config#CertificatePinning) of known-good certificates for these services instead of trusting pre-installed CAs. This can avoid some cases where an interception (*man-in-the-middle* attack) could be possible and lead to various security issues considering you're trusting the app to deliver you other apps.
@ -139,7 +139,9 @@ Moreover, [Play Store restricts the use of highly invasive permissions](https://
## Conclusion: what should you do?
F-Droid **weakens the security model of Android substantially** for all of the reasons above. While they could easily make some improvements, I don't think F-Droid is in an ideal situation to solve all of these issues because some of them are **inherent flaws** in their architecture. I'd also argue that their core philosophy is not aligned with some security principles expressed in this article. In any case, I can only wish for them to improve since they're one of the most popular alternatives to commercial app repositories, and are therefore trusted by a large userbase.
F-Droid is not the only way to get and support open-source apps. Sure, it can help you in finding one that you wouldn't have known existed otherwise. Many developers also publish their FOSS apps on the **Play Store** or their website directly. Most of the time, releases are available on **GitHub**, which is great since each GitHub releases page has an Atom feed. If downloading APKs from regular websites, you can use `apksigner` to validate the authenticity by comparing the certificate fingerprint against the fingerprint from another source (it wouldn't matter otherwise). This is how you may proceed to get the certificate:
F-Droid is not the only way to get and support open-source apps. Sure, it can help you in finding one that you wouldn't have known existed otherwise. Many developers also publish their FOSS apps on the **Play Store** or their website directly. Most of the time, releases are available on **GitHub**, which is great since each GitHub releases page has an Atom feed. If downloading APKs from regular websites, you can use `apksigner` to validate the authenticity by comparing the certificate fingerprint against the fingerprint from another source (it wouldn't matter otherwise).
This is how you may proceed to get the app certificate:
```
apksigner verify --print-certs --verbose myCoolApp.apk
@ -163,7 +165,7 @@ You can still find and get your open-source apps elsewhere. And no, open-source
> Isn't Google evil? Isn't Play Store spyware?
Some people tend to exaggerate the importance of Google in their threat model, at the cost of pragmatism and security/privacy good practices. Play Store isn't spyware and can run unprivileged like it does on GrapheneOS (including with unattended updates support). Unprivileged apps have always had the ability to [query installed packages](https://developer.android.com/training/package-visibility) on a given user profile.
Some people tend to exaggerate the importance of Google in their threat model, at the cost of pragmatism and security/privacy good practices. Play Store isn't spyware and can run unprivileged like it does on GrapheneOS (including with unattended updates support). For instance, unprivileged apps have always had the ability to [query installed packages](https://developer.android.com/training/package-visibility) on a given user profile.
**Play Store evidently has some privacy issues** given it's a proprietary service which requires an account (this cannot be circumvented), and Google services have a history of nagging users to enable privacy-invasive features. Again, some of these privacy issues can be mitigated by setting up the [Play services compatibility layer from GrapheneOS](https://grapheneos.org/usage#sandboxed-google-play) which runs Play services and Play Store in the regular app sandbox (the `untrusted_app` domain). This solution could very well be ported to other Android-based operating systems. If you want to go further, consider using a properly configured account with the least amount of personally indentifiable information possible (note that the phone number requirement appears to be region-dependent).