On 04/06/2012 02:06 AM, Branko Čibej wrote: > On 06.04.2012 00:38, C. Michael Pilato wrote: >> I've been also frustrated when considering the situation that occurs when a >> user changes his/her master password, forcing a re-encryption of all cached >> credentials using the new password. > > You could do what whole-disk encryption systems do: only the encyprtion > key is encrypted by the master passphrase, actual data are encrypted by > that key. This allows different users with different passphrases to > decrypt the same data, since they only decrypt a wrapped copy of the > same encryption key. > > In other words, changing the master passphrase only requires decrypting > and re-encrypting one 256-bit encryption key, not the whole credentials > store.
That's a neat concept. I presume that the encryption key is just some random data (since the user never needs to know it)? >> Is there anyone who is game for helping me tackle a new design for our >> client-side authn cache using SQLite? > > This makes me wonder if we couldn't perhaps keep the whole thing as an > in-memory-not-disk-backed SQLite database, then encrypt and dump the > whole SQLite memory snapshot to disk. The real trouble with that > approach is that debugging the database using the SQLite command-line > tools would be impossible, everything would have to happen through the > SVN API. > > (The point here is that, in this way, we could "easily" atomically > re-encrypt everything with a new master passphrase, as opposed to doing > it transactionally within an ordinary SQLite database -- because we > don't have control over what SQLite does with the free space in the > file, and it'd be really, really bad if snippets of data that had been > encrypted by the old, presumably compromised, passphrase ended up > sitting around on disk.) *sigh* I hadn't considered stale, compromised data not yet purged or overwritten. Does SQLite's VACUUM statement help with this problem? http://sqlite.org/lang_vacuum.html -- C. Michael Pilato <cmpil...@collab.net> CollabNet <> www.collab.net <> Distributed Development On Demand
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