11–20 of 42 posts
Something is twitching in the back of my mind about this. Sure, they can't look at the data based solely on the encrypted copy, but if they have a plaintext copy of a document of interest, they are able to determine which of their customers has that document, right? Doesn't that diminish some of the privacy claims?
Academic paper on convergent encryption: http://www.ssrc.ucsc.edu/Papers/storer-storagess08.pdf TL;DR version: take a chunk of data, encrypt it with its own sha1 hash as the key. Now you have an encrypted version that you can dedup. You can only decrypt if you already know the hash. Info about who owns any particular chunk is not kept on the server, so even if you break in to the server, all you can tell is which chu…
I have to imagine this mostly helps with OS files that are standard across man machines. Can't we ship a list of hashed client-side?
say you want to backup some data. and that data includes music or video... and the riaa or mpaa decide that bitcasa are facilitating pirating and should be shut down... so they reach a deal where all the data are checked against known songs or videos. and if they find a match then your identity will be provided for prosecution...
of course, if you are doing nothing wrong, you have nothing to fear. this can only identify known data. but even so, it is an interesting issue: "encryption" here doesn't have all the guarantees you might expect.
(there are more disturbing scenarios too. for example, perhaps a certain text is not illegal in the copyright sense, but is unacceptable politically.)
[disclaimer - this is from skimming the paper; i should say that i am no expert on this, so don't take my word as gospel]
This does introduce new avenues for attacks, however. You don't have to be able to decrypt to show that certain people have certain files.
Also, for files that contain just one piece of sensitive information and a the rest is predictable (i.e, the secret key file for a website back-end), you've effectively given up a hash of the secret which can then be brute-forced.
Academic paper on convergent encryption: http://www.ssrc.ucsc.edu/Papers/storer-storagess08.pdf TL;DR version: take a chunk of data, encrypt it with its own sha1 hash as the key. Now you have an encrypted version that you can dedup. You can only decrypt if you already know the hash. Info about who owns any particular chunk is not kept on the server, so even if you break in to the server, all you can tell is which chu…
The list of "who owns which hashes" must be stored on their servers, even if it's not the "same" server. Otherwise I would have to manually transfer my hashes from one computer to another.
"HP: What do you do in terms of encryption or security? TG: We encrypt everything on the client side. We use AES-256 hash, SHA-256 hashing for all the data. HP: So it’s encrypted all on the client side and you can’t look at it on the server side? TG: Exactly" Finally, a company that gets it. I've been asking for this for a while now. I wish Dropbox and all the others would do this, too. I get it that some of Dropbox'…
A problem remains "with full security" in that you have no idea what's going on in the binary client program. Reveal or open-source the client program and allow customers who need this end-to-end security to compile the program themselves.
Something is twitching in the back of my mind about this. Sure, they can't look at the data based solely on the encrypted copy, but if they have a plaintext copy of a document of interest, they are able to determine which of their customers has that document, right? Doesn't that diminish some of the privacy claims?
https://spideroak.com/blog/20100827150530-why-spideroak-does...
TL;DR: AES_key = SHA-256(file) This does introduce new avenues for attacks, however. You don't have to be able to decrypt to show that certain people have certain files. Also, for files that contain just one piece of sensitive information and a the rest is predictable (i.e, the secret key file for a website back-end), you've effectively given up a hash of the secret which can then be brute-forced.