Hi, first of all thanks for the input. I guess if you create a hash before encryption and only store the encrypted file if the hash doesn't exist the file/chunk has to be decrypted/encrypted by all users in the same way. Otherwise they would have to store your user specific encryption result. At least thats what I would think. There is actually an article on how they do the encryption: http://support.crashplan.com/doku.php/articles/encryption_key. Maybe there is still enough room for deduplication after the files have been encrypted. Could this be?
I hope I'm not bothering anyone with the questions. It just seems interesting to me since I always thought this was some kind of a tradeoff decision. On Mar 6, 8:46 am, Karsten Silz <[email protected]> wrote: > On 5 Mrz., 17:29, Sebastian Himberger > > <[email protected]> wrote: > > What I don't understand: If the encryption happens on the client side > > and is done right this shouldn't be possible, right? Or am I missing > > something? I'm certainly no expert on this. > > If I was to deduplicate on the client, I would calculate an SHA1 or > MD5 hash over a file and send it, together with the file name and the > file size, to the server. If a file with the exact same three > attributes already exists on the server, it's the same and you don't > need to send the file over. Otherwise, encrypt it and send it over. > > Calculating SHA1 or MD5 hash is pretty cheap, so it's worth it. This > works well for program or OS files, but fails for something like > iTunes music (though it doesn't have DRM in it anymore, it's > supposedly has your email address and some other metadata in it, so > one million Lady Gaga songs were all different). -- You received this message because you are subscribed to the Google Groups "The Java Posse" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/javaposse?hl=en.
