A mobile device for storing data, the mobile device comprising: a storage device (305, 310) configured to store data; transceiver circuitry (340, 345) configured to access a server via a wireless communication network and download an Android application package from the server; and a package manager configured to: analyze software resources in the downloaded Android application package; determine, among the software resources, at least one unnecessary software resource not suitable for use by the mobile device based on a policy configuration predetermined in relation to device parameters of the mobile device; delete the at least one unnecessary software resource; generate, from software resources remaining after deletion of the unnecessary software resources, an optimized Android application package having a smaller size than the downloaded Android application package; identify an original security certificate in the downloaded Android application package and generate a new security certificate for the optimized Android application package to be used for downloading an updated version of the Android application package; and store the optimized Android application package and a table associating the original security certificate and the new security certificate in the storage device (305, 310) in place of the downloaded Android application package. a storage device (305, 310) configured to store data; transceiver circuitry (340, 345) configured to access a server via a wireless communication network and download an Android application package from the server; and a package manager configured to: analyze software resources in the downloaded Android application package; determine, among the software resources, at least one unnecessary software resource not suitable for use by the mobile device based on a policy configuration predetermined in relation to device parameters of the mobile device; delete the at least one unnecessary software resource; generate, from software resources remaining after deletion of the unnecessary software resources, an optimized Android application package having a smaller size than the downloaded Android application package; identify an original security certificate in the downloaded Android application package and generate a new security certificate for the optimized Android application package to be used for downloading an updated version of the Android application package; and store the optimized Android application package and a table associating the original security certificate and the new security certificate in the storage device (305, 310) in place of the downloaded Android application package. analyze software resources in the downloaded Android application package; determine, among the software resources, at least one unnecessary software resource not suitable for use by the mobile device based on a policy configuration predetermined in relation to device parameters of the mobile device; delete the at least one unnecessary software resource; generate, from software resources remaining after deletion of the unnecessary software resources, an optimized Android application package having a smaller size than the downloaded Android application package; identify an original security certificate in the downloaded Android application package and generate a new security certificate for the optimized Android application package to be used for downloading an updated version of the Android application package; and store the optimized Android application package and a table associating the original security certificate and the new security certificate in the storage device (305, 310) in place of the downloaded Android application package.