Android App links with F-Droid - how can it work?

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1

I would like to try app links to create a gallery in a browser which blends in with the app, opening it on different pages.

As I understand, app links require sha signatures of the apk signing key in a file which is hosted on the website.
As I understand, F-Droid has the keys for signing the app. How can I make app links work, then?

Ideas:

  • It may not be necessary to use a singed thing here because e.g. Firefox allows opening the app from the urls in the manifest file either way.
  • The F-Droid server can create the signed file and I can just upload it - I can hide it in the app. This would require custom code execution during the signing process which is a security risk, so I guess not possible.
  • If the app can be signed twice, I would also allow sharing the second signing keys publicly, as F-Droid does not seem to allow hidden credentials and I would like others to allow their apps to blend in, too.
  • It seems it might be ok to host the app on Izzy’s repo to allow app links - I can build it with a CI server and sign it accordingly.
  • Since I might not be the first person having the hope to use app links in general, a unified approach might be nice. I.e. I could use a link like this: https://f-droid.org/en/packages/my.package.id/assetlinks.json which is generated by F-Droid automatically.
2

So you need the sha1sum from F-Droids key or ?

3

It seems, yes.The sum does not change with url or package id, so I think it is the sum of the F-Droid signing key. Thanks for asking! I can probably find that. I do not know where, yet.

4

I found it, I think: Bezugsquellen und Signaturen | F-Droid - Free and Open Source Android App Repository

This should now be the file content one can add to the web page:

[{
  "relation": ["delegate_permission/common.handle_all_urls"],
  "target": {
    "namespace": "android_app",
    "package_name": "eu.quelltext.coloring",
    "sha256_cert_fingerprints":
    ["43:23:8D:51:2C:1E:5E:B2:D6:56:9F:4A:3A:FB:F5:52:34:18:B8:2E:0A:3E:D1:55:27:70:AB:B9:A9:C9:CC:AB"]
  }
}]