Systems and methods for secure file portability between mobile applications in a cloud-based environment or cloud-based collaboration and file sharing environment. In one embodiment, a server-based key generation service generates an encryption key that is unique to each file transfer transaction between mobile applications accessed via a mobile device. Data packages leaving a mobile application are then encrypted using the encryption key to provide secure file portability between mobile applications. In another embodiment, a background service triggered by a mobile application detects when a user is logged out of the mobile application and revalidates the user session with the mobile application to maintain portability of files between mobile applications. The background service presents a minimal user interface to get the user's credentials for the mobile application, without the user having to switch to the mobile application, and obtains an authentication token from a remote server using the user's credentials.