Identification of Signed and Unsigned Android APK file.

Identification of Signed and Unsigned Android APK file.

1. Goto command prompt. 
2. C:\prgram files\java\jdk1.7.0\bin>jarsigner.exe –verify –verbose –certs “D:\shared folder\Armstrong.APK” or you can use C:\prgram files\java\jdk1.7.0\bin>jarsigner.exe –verify “D:\shared folder\Armstrong.APK”  - Enter. It prints jar verified. If you see “S  ------ META-INF/MANIFEST.MF” at the end, it means your apk is signed.
3. If it prints “no manifest” jar is unsigned, it means your apk is unsigned .
4. There are two modes to build an app 1) Debug mode 2) Release mode. When using debug mode to build your app, the SDK tools invoke Keytool to automatically create a debug keystore and key. This debug key is then used to automatically sign the APK, so you do not need to sign the package with your own key.
5. By default, your IDE will sign your apk with a debug key, which will allow users to install it on their device if they check the "use for development" boxes in the Settings. 
6. In order to publish to the market, you have to sign it with release key, which allows user to install it without enabling additional settings. 
7. More importantly, you cannot run an unsigned APK file. No device or emulator will support it.