Creating Release Keys and Signing Builds

http://www.kandroid.org/online-pdk/guide/release_keys.html

• platform: a key for packages that are part of the core platform. 
• shared: a key for things that are shared in the home/contacts process. 
• media: a key for packages that are part of the media/download system. 
• releasekey: the default key to sign with if not otherwise specified

[Note] LOCAL_CERTIFICATE in Android.mk