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gerrit-public.fairphone.software / platform / tools / apksig / 948b54bdf0365e620fcedad759fec46ae134f866
commit948b54bdf0365e620fcedad759fec46ae134f866[log] [tgz]
authorMichael Groover <mpgroover@google.com>Wed Jun 10 10:53:14 2020 -0700
committerMichael Groover <mpgroover@google.com>Wed Jun 10 11:09:25 2020 -0700
tree639523cb26a83ccacb4785d1d84575d650bfa583
parent86a6343574b91c45aa3e8884b998a87e9a16fcda [diff]
Use min SDK or default 1 when target SDK not specified

The apksig target SDK version minimum signature scheme check uses the
targetSdkVersion of the uses-sdk element to determine the minimum
signature scheme version to verify. If this attribute or the uses-sdk
element is not specified in the APK then the verifier should behave as
the platform and use the value of the minSdkVersion as the target or
a default value of 1 is neither is specified.

Bug: 148313868
Test: gradlew test
Change-Id: I79f6f80870c402fc603a7e01f9d76afaf0d1c3c3
3 files changed
tree: 639523cb26a83ccacb4785d1d84575d650bfa583
  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.