Re: [Duplicity-talk] Encrypted Diffs

[Gabriel Ambuehl]

On 16.1.10 Michael Orlitzky wrote:
> So, incremental encrypted backups are supposed to be hard. I've searched 
> through all of the documentation I can find (short of digging into the 
> source), and haven't been able to locate a good description of how 
> Duplicity solves the problem. If possible, can someone explain the 
> sequence of events that takes place when one creates an incremental 
> encrypted backup?
> 
> In particular, the question I'm trying to answer is, "how do we 
> calculate the difference between two encrypted blobs?". Do GPG/tar 
> provide random access within an archive? Or does Duplicity just diff 
> whatever comes out of the stream? Etc.

As far as I understand: Duplicity downloads the encrypted rsync data stored on 
the other side (that would usually be transmitted when using rsync but 
generated on the fly by the rsync on the other end) and runs rsync algo against 
it. Works surprisingy well.