signapk - JAR and APK signing tool

       The Android Open Source Project.

                                                                                                      SIGNAPK(1)

       Signs ZIP files, including JARs, APKs and Over-The-Air (OTA) updates, in a way compatible with  Android's
       mincrypt  verifier,  using EC or RSA keys and SHA1 or SHA-256.  The tool can additionally sign APKs using
       APK Signature Scheme v2.  It is the standard tool used to sign APK and JAR files distributed as  part  of
       Android ROMs.

       Prior to the KitKat (aka 4.4.2 aka android-19) release, signapk ignored the signature algorithm specified
       in the certificate and always used SHA1withRSA.

       Starting  with JellyBean-MR2 (aka 4.3 aka android-18), the platform supports SHA256withRSA, so we use the
       signature algorithm in the certificate to select which to use (SHA256withRSA or  SHA1withRSA).   Also  in
       JellyBean-MR2, EC keys are supported.

       Because  there  are old keys still in use whose certificate actually says “MD5withRSA”, those are treated
       as though they say “SHA1withRSA” for compatibility with older releases.

       signapk - JAR and APK signing tool

JAR(1)

       ZIP(1)

       ZIPALIGN(1)

       https://source.android.com/devices/tech/ota/sign_builds.html

       Command line tool for signing Android ZIP/JAR/APK files:

       signapk  [-w]  [-a  alignment]  [-providerClass  className] publickey.x509[.pem] privatekey.pk8 [publick‐ey2.x509[.pem] privatekey2.pk8 ...] input.jaroutput.jarsignapkfile.jarinput.jar is an existing file to sign.