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gerrit-public.fairphone.software / platform / tools / apksig / 72fd03affc104d64f3131f19cada85eaff4bff76
commit72fd03affc104d64f3131f19cada85eaff4bff76[log] [tgz]
authorMichael Groover <mpgroover@google.com>Wed Nov 03 14:15:18 2021 -0700
committerMichael Groover <mpgroover@google.com>Wed Nov 03 14:15:18 2021 -0700
tree6b4c7f13f1d6b498d9e18fa4a6925332fcc014e0
parent9d96cb526207a61e47948f7ec1fb590ff9dda8cb [diff]
Document issue with non-default capabilities for shared signers

Prior to Android S, when multiple apps share a common signer in their
signing lineage with non-default capabilities, the platform would
assign the capabilities declared for this signer in one of the app's
lineage to the same signer in the lineage of the rest of the apps.
This commit updates the developer signing docs to ensure developers
are aware of this issue.

Bug: 201588245
Test: gradlew test
Change-Id: If3e6395efdfe1a6c926933d3d6ee3857df1d6841
1 file changed
tree: 6b4c7f13f1d6b498d9e18fa4a6925332fcc014e0
  1. etc/
  2. src/
  3. Android.bp
  4. android_plugin_for_gradle.gradle
  5. build.gradle
  6. LICENSE
  7. OWNERS
  8. README.md
README.md

apksig

apksig is a project which aims to simplify APK signing and checking whether APK signatures are expected to verify on Android. apksig supports JAR signing (used by Android since day one) and APK Signature Scheme v2 (supported since Android Nougat, API Level 24). apksig is meant to be used outside of Android devices.

The key feature of apksig is that it knows about differences in APK signature verification logic between different versions of the Android platform. apksig thus thoroughly checks whether an APK's signature is expected to verify on all Android platform versions supported by the APK. When signing an APK, apksig chooses the most appropriate cryptographic algorithms based on the Android platform versions supported by the APK being signed.

The project consists of two subprojects:

  • apksig -- a pure Java library, and
  • apksigner -- a pure Java command-line tool based on the apksig library.

apksig library

apksig library offers three primitives:

  • ApkSigner which signs the provided APK so that it verifies on all Android platform versions supported by the APK. The range of platform versions can be customized.
  • ApkVerifier which checks whether the provided APK is expected to verify on all Android platform versions supported by the APK. The range of platform versions can be customized.
  • (Default)ApkSignerEngine which abstracts away signing APKs from parsing and building APKs. This is useful in optimized APK building pipelines, such as in Android Plugin for Gradle, which need to perform signing while building an APK, instead of after. For simpler use cases where the APK to be signed is available upfront, the ApkSigner above is easier to use.

NOTE: Some public classes of the library are in packages having the word "internal" in their name. These are not public API of the library. Do not use *.internal.* classes directly because these classes may change any time without regard to existing clients outside of apksig and apksigner.

apksigner command-line tool

apksigner command-line tool offers two operations:

  • sign the provided APK so that it verifies on all Android platforms supported by the APK. Run apksigner sign for usage information.
  • check whether the provided APK's signatures are expected to verify on all Android platforms supported by the APK. Run apksigner verify for usage information.

The tool determines the range of Android platform versions (API Levels) supported by the APK by inspecting the APK's AndroidManifest.xml. This behavior can be overridden by specifying the range of platform versions on the command-line.