Open JDK (version 8 is required, more recent versions won't work)
Creating key for debug
keytool -keyalg RSA -genkeypair -alias androiddebugkey -keypass android -keystore debug.keystore -storepass android -dname "CN=Android Debug,O=Android,C=US" -validity 9999 -deststoretype pkcs12
Creating key for release
keytool -v -genkey -keystore mygame.keystore -alias mygame -keyalg RSA -validity 10000
This keystore and key are used to verify your developer identity, remember the password and keep it in a safe place!
Take a look here Link