apksigcopier(1)

NAME
apksigcopier - copy/extract/patch android apk signatures & compare apks

SYNOPSIS
apksigcopier copy [options] signed_apk unsigned_apk output_apk

apksigcopier extract [options] signed_apk output_dir

apksigcopier patch [options] metadata_dir unsigned_apk output_apk

apksigcopier compare [options] first_apk second_apk

apksigcopier --version

apksigcopier --help

apksigcopier [command] --help

DESCRIPTION
A command line 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.

COMMANDS

  copy
Copy (extract & patch) signatures from signed to unsigned APK.

  extract
Extract APK signatures from signed APK.

  patch
Patch extracted APK signatures onto unsigned APK.

  compare
Compare two APKs by copying the signature from the first to a copy of the second and checking if the resulting APK verifies.

This command requires apksigner(1).

NB: copying from an APK v1-signed with signflinger to an APK signed with apksigner works, whereas the reverse fails; see the FAQ in the README.

OPTIONS

  copy/extract/patch
--v1-only [no|auto|yes]

Whether to expect only a v1 signature: no means a v2 signature is expected as well, auto means the presence of a v2 signature is detected automatically, and yes means a v2 signature is not expected (and ignored if it does exist). Default: no.

You can also set the environment variable APKSIGCOPIER_V1_ONLY instead.

  compare
--unsigned

Accept unsigned second_apk.

--min-sdk-version

Passed to apksigner(1) when verifying.

--verify-cmd

Command (with arguments) used to verify APKs. Default: apksigner verify.

ENVIRONMENT VARIABLES
The following environment variables can be set to 1, yes, or true to override the default behaviour.

  APKSIGCOPIER_EXCLUDE_ALL_META
Exclude all metadata files, not just MANIFEST.MF.

  APKSIGCOPIER_COPY_EXTRA_BYTES
Copy extra bytes after data (e.g. an existing v2 signature).

  APKSIGCOPIER_SKIP_REALIGNMENT
Skip realignment of ZIP entries.

EXAMPLES

  extract

        $ mkdir meta
        $ apksigcopier extract signed.apk meta
        $ ls -1 meta
        8BEA2A77.RSA
        8BEA2A77.SF
        APKSigningBlock
        APKSigningBlockOffset
        MANIFEST.MF

  patch

        $ apksigcopier patch meta unsigned.apk out.apk

  copy

        $ apksigcopier copy signed.apk unsigned.apk out.apk

  compare

        $ apksigcopier compare foo-from-fdroid.apk foo-built-locally.apk
        $ apksigcopier compare foo.apk --unsigned foo-unsigned.apk

SEE ALSO
apksigner(1)

COPYRIGHT
Copyright © 2023 FC Stegerman. License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html . This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

AUTHORS
FC Stegerman flx@obfusk.net