Following up on my post on BitTorrent Sync here is some more information and use cases.
There is at least one alternative to BitTorrent Sync that is open source: Seafile is a cloud service. I have only read about it on their website but it looks interesting.
Now to the use case:
If you are like me you are storing lots of data on your smartphone, in particular passwords and other sensitive data. While it is convenient to have this data with you all the time there is always the danger of the phone being lost or stolen and – if you are paranoid enough – the data being stored on Google’s servers (or the servers of a different cloud service).
Of course there are many options to encrypt the data on your phone like KeePass etc. What I don’t like about these solutions is the fact that they encrypt everything, not just the sensitive parts. So if I just want to look up the URL of a website which I use so infrequently that I tend to forget it, this is rather cumbersome. Therefore I use plain text files and encrypt only the parts I deem sensitive (passwords etc.), using the txtCrypt app. Since there exist alternative implementations of the txtCrypt algorithm, including a Web App I can be sure to still get to the encrypted parts even if my phone is not available for decryption.
The other problem with the phone getting stolen is backup and accessing the backup without another phone. There are lots of note keeping apps that synchronize with cloud services (e.g. Google Keep, Evernote or Flick Note). I used all of them for a while to try finding the one that I like best. Unfortunately I didn’t feel comfortable in the knowledge that I have no control over how and where the data is stored, so I abandoned them for the text file approach. For the backup part I have started using the BitTorrent Sync app to sync to my desktop computer (which is backed up anyway). There is another advantage of this approach: You can add and edit files using a real keyboard and the text editor of your choice rather than the virtual keyboard on your phone.