Comment by andrewcooke | Hacker News Reader

Comment by andrewcooke | Hacker News Reader

i have a question about their authentication process as described at http://blog.filerock.com/2012/06/filerock-security-overview/

they say that they don't send the password over the net, but send instead the result from PBKDF2. but how does that make things more secure? couldn't someone simply snoop the PBKDF2 output and send that themselves? (if they could eavesdrop at all - my point is not that eavesdropping is possible, but that a transformed password is equivalent to the password itself).

i thought perhaps they provided a different random seed for PBKDF2, but then they would get a different answer each time and wouldn't be able to check it.

i get why PBKDF2 is better than just using a "simple" password. but i don't get why they make a point of saying your password is not transmitted. i mean, HTTP basic auth uses a hash, but that's considered just as insecure as the password for exactly this reason. and PBKDF2 is just a a glorified hash.

it just seems confused. claiming something is an advantage when it's not, as far as i can tell (although i suspect the confused party is me - it just reminded me so much of http basic auth...).

the point is that in FileRock, several things depend on your password, and some of them must be kept confidential and never sent even to the FileRock servers.

You are right, from the only point of view of the authentication, using a password gives you the same level of security as using one of its derivations (given a deterministic generation of the derivations and a password with same length and randomness of its derivations).

The mechanism that actually protects your credentials from being sniffed and used to get the first level of access to your account, is the industry standard SSL/TLS.

But even if someone discovers which is the derivation that you use to authenticate with the FileRock servers, they won't be able to know your password. And that means that the other derivations of your password (for example, the one used to protect the encryption keys for your data) are not disclosed as well. Therefore, even the people managing the FileRock servers will not know them, and they will not be able to access your encrypted data.

I hope this will solve your doubts.

PS: I see now that evv and notimetorelax also replied and they are correct.

thanks; that makes more sense.

I can't speak on behalf of FileRock, but I suspect the following, based off of the blog post you linked:

While the PBKDF2'd password CAN theoretically be snooped (if this wasn't wrapped in TLS, it would be trivial), the actual password cannot be calculated from the derivation.

So yes, an attacker who listened to your transmitted PBKDF2'd password can theoretically access your encrypted files from the server. However, if they could snoop, they could have just watched those encrypted files as they came across the wire.

The client-side encryption is still just as effective. As far as I can tell, your data would still be safe.

I think it makes sense because they also provide client side encryption, essentially with the same key as user password. Read paragraph on client side encryption here: http://blog.filerock.com/2012/06/filerock-security-overview/

Reply on news.ycombinator.com