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On Fri, Apr 24, 2009 at 03:45:16PM -0400, Bill Moran wrote:
> In response to tomas@tuxteam.de:
[...]
> Someone hijacking your live server does not automatically give anyone
> the key, unless you implement this wrong (which is, of course, possible).
>
> Each _user_ gets their own key, encrypted with their password. Thus,
> even if an attack gets an offline dump of the database, it does them
> no good unless they already have the user's password. If they have
> that, they they've been given license to bypass your security
> restrictions _without_ doing anything funky.
Sorry, I was unclear: what I meant was the "live" server in the sense
that it's running (so either by physical access or via a trojan). In
this case the keys have to be around somewhere (say in RAM) -- as
opposed to the "quiescent" server (there I agree: keys are locked, or
better: not even there).
> But it's still protected. If an attacker manages to get an offline
> copy of the database (let's imagine a horrific scenario where they
> steal an unencrypted backup tape, or they find a huge SQL injection
> hole that allows them access to the entire database ...) they still
> only have access to the data for users that they know the password
> for. Even if they have a certain user's password, it only unlocks a
> single key, which only unlocks that user's data.
Not if the users have already provided the password and unlocked their
keys (i.e. they are working with the database).
> Sure, there are challenges, but there are methods to work through all
> of those challenges.
I seem to be less optimistic than you are: I think as soon as the server
"has" all the necessary key material to decrypt the data you are't more
secure than a "traditional" system, with some access control.
Regards
- -- tomás
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