copy/extract/patch android apk signatures & compare apks

 apksigcopier is a tool for copying android APK signatures from a signed APK to
 an unsigned one (in order to verify reproducible builds). It can also be used
 to compare two APKs with different signatures. Its command-line tool offers
 four operations:
 .
  * copy signatures directly from a signed to an unsigned APK
  * extract signatures from a signed APK to a directory
  * patch previously extracted signatures onto an unsigned APK
  * compare two APKs with different signatures (requires apksigner)