While Dropbox continues to lead the way in easy-to-use cloud-based file synchronization, recent security- and privacy-related lapses have left many Dropbox-loving lawyers looking for alternatives. To date there has been a lack of viable options, but AeroFS, a new startup, is looking to become the Dropbox for security-conscious users.
AeroFS offers the same ease-of-use that characterizes Dropbox, but adds a new spin to how file synchronization works: rather than storing your files in the "cloud", as is the case with Dropbox, AeroFS synchronizes files directly between your devices via an encrypted channel. This "peer-to-peer" synchronization technique means your data never has to be stored on a third-party server – if you access a file stored on your AeroFS account on, say, your iPhone, your data will be fetched from one of your connected AeroFS devices – likely your laptop or desktop computer.
AeroFS's approach has several benefits. First, you maintain direct control of sensitive data, as your files are never stored on AeroFS's servers. Second, you can synchronize as many files as you like (even extremely large files) without having to pay additional fees – because no cloud storage is used, AeroFS's costs remain the same whether you're synchronizing 100MB or 100GB of data.
A pure peer-to-peer file synchronization approach does come with some downsides: because files are synchronized directly between your devices, you need to leave at least one connected device powered on at all times if you want to be able to synchronize files on demand. Also, because your files are not stored in the cloud, you don't benefit from the backup and redundancy of having files stored in the cloud.
AeroFS addresses this downside by allowing you to store select files in the AeroFS cloud, thus delivering all the benefits of Dropbox's cloud-based file synchronization while allowing you to keep especially sensitive files stored locally on your own devices.
One other option for the privacy concious would be SpiderOak.com.
SpicerOak is very similar to DropBox, except that the encryption keys for your data are generated on your computer, so that the SpiderOak systems administrators cannot access your data stored on their servers. The down side is that if you loose your password, your data cannot be recovered by the SpiderOak admins. SpiderOaks pricing is also somewhat lower than DropBox's.