Being one of the most basic security methods, it’s important that every device supports strong encryption. Many OEMs these days ship their devices with dedicated encryption hardware. While this is beneficial, it’s also expensive. As such, dedicated hardware has typically been restricted for mid to high tier devices. This is not to say that low-end devices cannot support encryption, but without hardware accelerated encryption the overall user experience is degraded because of slow read/write times. That’s where Adiantum comes in.
Scoped Storage is a new safeguard being employed to restrict apps from reading/writing files in external storage that are not contained within their own sandboxed app-specific directory. Google’s goal is three-fold: better attribution of which apps have control over which files, the protection of app data, and the protection of user data.
Google is doubling down on the MediaStore API for shared audio, video, and picture content. By default, all apps can insert, modify, or delete their own files to the MediaStore.Images, MediaStore.Video, and MediaStore.Audio collections without needing any permissions. Android Q also adds a new MediaStore.Downloads collection to store user-downloaded content, which all apps using the MediaStore API can contribute to. While files stored in sandboxed app-specific directories are deleted upon uninstallation, all files contributed to the MediaStore collections persist beyond uninstallation.
To access any files created by another app—whether the file is in one of the MediaStore collections or outside of them—the app must use the Storage Access Framework. Furthermore, EXIF metadata of images is redacted unless your app has the new ACCESS_MEDIA_LOCATION permission granted. In Android Q, apps can also control which storage device to land media on by querying its volume name using getExternalVolume().
Google initially imposed Scoped Storage restrictions on all apps in Android Q regardless of their target API levels, but after feedback, the company is giving developers more time to make adjustments. The full details on the Scoped Storage changes can be found on this page, and you can find out more about Google’s recommendations on the best practices for shared storage by watching this Google I/O talk.
