Since the Snowden revelations we have all started to think about security much more actively. Despite this services like Dropbox that store and sync our data in the cloud are still too useful to avoid. There is a trade-off between security and usability an ideal situation would give you the synchronisation as well as a security. Boxcryptor is a third-party add-on that runs on files on multiple services such as Google Drive and Dropbox and lets you store keep storing your files online but keeps them private ans secure from those services.
The service runs as an extra program on your PC or smart phone and encrypts each file as it is uploaded to the cloud. The cloud provider stores the file but there is no way for them to do anything with it without the key that only you have.
The service works with most types of cloud storage including Dropbox, Google Drive, OneDrive, Box.net and all of those that use WebDav like Cubby and HiDrive. The free version of the software works with only one at once, but the paid works with as many as needed.
There are two basic plans available. The free plan is limited to one provider, two devices and will not let you encrypt the file names. The personal plan is $48 a year (around £28) but there is a 25% student discount available. A business plan is also available that includes groups and commercial use rights.
In theory Boxcryptor should give you the best of both worlds with cloud storage. Part of your storage could be insecure to allow for uploading of photos and other programs hooked into it and the remainder could be secure and private. I have installed Boxcryptor on my system and will do a full review in the coming weeks.