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Wonderfall 2022-01-09 18:03:59 +01:00
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@ -24,11 +24,11 @@ On the other hand, Play Store now manages the app signing keys too, as [Play App
F-Droid requires that the source code of the app is exempt from any proprietary library or ad service, according to their [inclusion policy](https://f-droid.org/en/docs/Inclusion_Policy/). Usually, that means that some developers will have to maintain a slightly different version of their codebase that should comply with F-Droid's requirements. Besides, their "quality control" offers **close to no guarantees** as having access to the source code doesn't mean it can be easily proofread. Saying Play Store is filled with malicious apps is beyond the point: the **false sense of security** is a real issue. Users should not think of the F-Droid main repository as free of malicious apps, yet unfortunately many are inclined to believe this.
> How can you be sure that the app repository can be hold to account for the code it delivers?
> How can you be sure that the app repository can be held to account for the code it delivers?
F-Droid's answer, interesting yet largely unused, is [build reproducibility](https://f-droid.org/en/docs/Reproducible_Builds/). While deterministic builds are a neat idea in practice, it requires the developer to make their toolchain match with what F-Droid provides. It's additional work on both ends sometimes resulting in [apps severely lagging behind in updates](https://code.briarproject.org/briar/briar/-/issues/1612), so reproducible builds are not as common as we would have wanted. It should be noted that reproducible builds in the main repository can be exclusively developer-signed.
Google's approach is [code transparency for app bundles](https://developer.android.com/guide/app-bundle/code-transparency), which is a simple idea addressing some of the concerns with Play App Signing. A JSON Web Token (JWT) signed by a key private to the developer is included in the app bundle before its upload to Play Store. This token contains a list of DEX files and native `.so` libraries and their hashes, allowing end-users to verify that the running code was built and signed by the app developer. Code transparency has known limitations, however: not all resources can be verified, and this verification can only be done manually since it's not part of the Android platform itself (so requiring a code transparency file cannot be enforced by the OS right now). Despite its incompleteness, code transparency is still helpful, easy to implement, and thus something we could see more often as time goes by.
Google's approach is [code transparency for app bundles](https://developer.android.com/guide/app-bundle/code-transparency), which is a simple idea addressing some of the concerns with Play App Signing. A JSON Web Token (JWT) signed by a key private to the developer is included in the app bundle before its upload to Play Store. This token contains a list of DEX files and native `.so` libraries and their hashes, allowing end-users to verify that the running code was built and signed by the app developer. Code transparency has known limitations, however: not all resources can be verified, and this verification can only be done manually since it's not part of the Android platform itself (so requiring a code transparency file cannot be enforced by the OS right now). Despite its incompleteness, code transparency is still helpful, easy to implement, and thus something we should see more often as time goes by.
## 2. Slow and irregular updates
Since you're adding one more party to the mix, that party is now responsible for delivering proper builds of the app: it's a common thing among traditional Linux distributions and their packaging system. They have to catch up with *upstream* on a regular basis, but very few do it well (Arch Linux comes to my mind). Others, like Debian, prefer making extensive *downstream* changes and delivering security fixes for a subset of vulnerabilities assigned to a CVE (yeah, it's as bad as it sounds, but that's another topic).