Having the files backup in the cloud doesn't mean that they are safe from hackers. Sure, they are safer than in your phone or tablet, but the cloud can be hacked as well. The Boxcryptor application makes sure that the files are encrypted before being uploaded, adding an extra layer of security.
The application comes with support for all of the major cloud storage providers, including Dropbox, Google Drive or Microsoft OneDrive. It also provides continuous access to all of the files stored in the cloud, and the encryption and decryption are done only on your device.
The encryption process uses AES-256 standard, and the Boxcryptor Unlimited version of the app can also use filename encryption.