One thing that almost all online backup solutions (e.g.. Dropbox, CX, Memopal, etc.) have in common is that they don’t allow the user to store encrypted files on their storage. They encrypt the connection from user’s computer to the cloud service, but once the files are there, they will be stored either unencrypted or encrypted with a key that the service provider has. This practice allows the provider to index the files and check their checksum. Once a file has a known checksum (usually SHA1) it will no longer be uploaded to the storage, it will be only referenced, in order to spare some space. Although this allows the provider to massively optimize the storage, this has a major drawback: zero privacy for the user. If somebody hacks the storage (see Dropbox’s privacy problems in the past) then your files will be available unencrypted to the attacker. In the light of the NSA surveillance, this means that they can get their hands on your files without any problem at all. In the last two years it seems that the problem started to be solved by some providers (e.g. Wuala) which saw the opportunity and offered upload of the files which…