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f6d1d548e4
Google re-signs Play-delivered apps, so the release key is only the upload key there and signs the AAB we send; the installed app verifies against Google's app signing certificate. The release key also signs the GitHub-release APK.
58 lines
1.9 KiB
Markdown
58 lines
1.9 KiB
Markdown
# Verifying a subtracks download
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subtracks ships through four channels:
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- **GitHub releases** — the APK is signed with the release key. Every release
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attaches the public certificate `release-certificate.pem` and a `SHA256SUMS`.
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- **Google Play** — uses Play App Signing, so Google re-signs the app it
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delivers. The release key is only the *upload* key there: it signs the AAB we
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send to Play, not the APK users install. The installed app verifies against
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Google's app signing certificate (Play Console → App integrity), and the upload
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key only proves the AAB we uploaded.
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- **`next` builds** (the `subtracks-next` artifact from CI) — signed with the
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public debug key committed here as [`next-certificate.pem`](next-certificate.pem).
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- **F-Droid** — re-signed by F-Droid with its own key; see F-Droid's published
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signing key.
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## `next` builds
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Certificate SHA-256:
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```
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DF:31:3F:18:58:E9:AD:F4:7F:44:65:B2:80:8F:DC:E5:B9:F8:8A:48:35:DC:D0:79:95:19:61:C3:05:05:08:37
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```
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To check a `next` APK:
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```sh
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apksigner verify --print-certs subtracks-next.apk
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```
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The `SHA-256 digest` line must equal the fingerprint above (the certificate is
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committed at [`next-certificate.pem`](next-certificate.pem)).
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## GitHub releases
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Each release attaches the APK, the checksums and the certificate:
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```sh
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sha256sum -c SHA256SUMS
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apksigner verify --print-certs subtracks.apk # compare with the .pem
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keytool -printcert -file release-certificate.pem # prints its SHA-256
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```
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The signing certificate SHA-256 is also listed in the release notes.
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## Google Play
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The AAB we upload is signed with the release (upload) key, and that is what Play
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checks; Google then re-signs the delivered APKs with its own app signing key. So
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a Play-installed app is verified against Play's app signing certificate (shown in
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Play Console → App integrity), not `release-certificate.pem`.
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To check the AAB that was sent:
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```sh
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keytool -printcert -jarfile app-release.aab
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```
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