How to Sign an Already Compiled Apk

Question

create a key using

keytool -genkey -v -keystore my-release-key.keystore -alias alias_name -keyalg RSA -keysize 2048 -validity 10000

then sign the apk using :

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore my_application.apk alias_name

check here for more info

Automated Process:

Use this tool (uses the new apksigner from Google):

https://github.com/patrickfav/uber-apk-signer

^{Disclaimer: Im the developer :)}

Manual Process:

Step 1: Generate Keystore (only once)

You need to generate a keystore once and use it to sign your unsigned apk. Use the keytool provided by the JDK found in %JAVA_HOME%/bin/

keytool -genkey -v -keystore my.keystore -keyalg RSA -keysize 2048 -validity 10000 -alias app

Step 2 or 4: Zipalign

zipalign which is a tool provided by the Android SDK found in e.g. %ANDROID_HOME%/sdk/build-tools/24.0.2/ is a mandatory optimization step if you want to upload the apk to the Play Store.

zipalign -p 4 my.apk my-aligned.apk

Note: when using the old jarsigner you need to zipalign AFTER signing. When using the new apksigner method you do it BEFORE signing (confusing, I know). Invoking zipalign before apksigner works fine because apksigner preserves APK alignment and compression (unlike jarsigner).

You can verify the alignment with

zipalign -c 4 my-aligned.apk

Step 3: Sign & Verify

Using build-tools 24.0.2 and older

Use jarsigner which, like the keytool, comes with the JDK distribution found in %JAVA_HOME%/bin/ and use it like so:

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my.keystore my-app.apk my_alias_name

and can be verified with

jarsigner -verify -verbose my_application.apk

Using build-tools 24.0.3 and newer

Android 7.0 introduces APK Signature Scheme v2, a new app-signing scheme that offers faster app install times and more protection against unauthorized alterations to APK files (See here and here for more details). Therefore, Google implemented their own apk signer called apksigner (duh!) The script file can be found in %ANDROID_HOME%/sdk/build-tools/24.0.3/ (the .jar is in the /lib subfolder). Use it like this

apksigner sign --ks-key-alias alias_name --ks my.keystore my-app.apk

and can be verified with

apksigner verify my-app.apk

The official documentation can be found here.

fastest way is by signing with the debug keystore:

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore ~/.android/debug.keystore app.apk androiddebugkey -storepass android

or on Windows:

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore %USERPROFILE%/.android/debug.keystore test.apk androiddebugkey -storepass android

You use jarsigner to sign APK's. You don't have to sign with the original keystore, just generate a new one. Read up on the details: http://developer.android.com/guide/publishing/app-signing.html

For those of you who don't want to create a bat file to edit for every project, or dont want to remember all the commands associated with the keytools and jarsigner programs and just want to get it done in one process use this program:

http://lukealderton.com/projects/programs/android-apk-signer-aligner.aspx

I built it because I was fed up with the lengthy process of having to type all the file locations every time.

This program can save your configuration so the next time you start it, you just need to hit Generate an it will handle it for you. That's it.

No install required, it's completely portable and saves its configurations in a CSV in the same folder.

Updated answer

Check https://shatter-box.com/knowledgebase/android-apk-signing-tool-apk-signer/

Old answer

check apk-signer a nice way to sign your app