It is possible to design a Dropbox-like system with the following properties:
1. Files are stored encrypted.
2. The service provider does not have the ability to arbitrarily decrypt the files. By "arbitrarily decrypt" I mean decrypt at any time they wish. They will be able to decrypt if the owner's client is actively connected.
3. When someone uploads a file that is identical to an existing file, it initially is stored separately, but in most cases can be eventually de-duplicated, without compromising #1 or #2.
1. Files are stored encrypted.
2. The service provider does not have the ability to arbitrarily decrypt the files. By "arbitrarily decrypt" I mean decrypt at any time they wish. They will be able to decrypt if the owner's client is actively connected.
3. When someone uploads a file that is identical to an existing file, it initially is stored separately, but in most cases can be eventually de-duplicated, without compromising #1 or #2.
I'll leave the details as a fun exercise.