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Is it safe to keep KeePass password database file in Dropbox? Database can have long (14+ alpha, numeric, special character) password and local Key file on machine or on mobile which is not shared in Dropbox?
TusharG
Posted 2011-10-28T10:41:14.223
Reputation: 1 352
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The question here is not whether you trust dropbox, but whether you trust keypass. If your password vault gives up its secrets when someone else gets hold of it, then you will want to find something else.
Keypass uses AES-256 for encryption, which remains the de facto standard, and SHA-256 to create a key from your passphrase along with a salt.
So the encryption method is good. So then you'll want to consider if there are any implementation weaknesses that can be exploited by someone getting hold of your vault. Well keepass seems to do a rolling encryption method, where the file is split into blocks and multiply encrypted. A brute force attack would take time, and you can increase the keys per second that can be tested when creating the database. Choose for it to do many rounds. This means that it takes time for a key to be tested. For you, it means you have to wait for a second or so for the database to open. For an attacker, it means they have to wait a second or so to test their next key.
There are other protection methods employed, but aren't relevant to this scenario, like keeping the vault contents encrypted in memory when the vault is open.
You should review the security methods used, and if you feel happy that if the vault fell into the wrong hands that you'd be safe, then go for it.
Paul
Posted 2011-10-28T10:41:14.223
Reputation: 52 173
This info doesn't appear to apply for older KeePass files, and may not apply in future. .kdb files allowed twofish encryption as well as AES. The more recent.kdbx` file format has a header field allowing for other encryption cyphers to be used, but KeePass2 only supports AES encryption. There's some info on the file formats here, though it's not authoritative.
1@Blaisorblade migrating to a different encryption standard in future is of little relevance for protecting the data you store in the format described today. You have to assume that the attacker might keep a copy of the file a while for future decryption. – mc0e – 2018-04-30T08:12:28.410
I was horrified to log in to the Dropbox web portal to find that my KeePass file listed as "Shared". I would never knowingly share it with anyone. – Tom Russell – 2019-09-06T01:55:19.707
1For me it is very important to get access of keepass database on my mobile however keeping it in sync is a big problem. For now I'll take a chance and use complex big password with local Key file as double security and keep it in dropbox while I will store key file on mobile filesystem and on HDD on computer. I know their is a risk. – TusharG – 2011-10-28T17:54:16.410
2What happens in the (very distant) future when AES-256 will be breakable? Dropbox keeps old revisions of files, so your passwords will be at risk, even if you have upgraded to a more secure mechanism by then. Any thoughts? – doublehelix – 2012-06-17T17:21:36.203
1@flixfe It keeps 30 days of revisions, so there is a window of opportunity there. A delete feature request to dropbox, or an alternative cloud storage solution that permits deletes of revisions or doesn't have them at all would fix this. – Paul – 2012-06-17T22:16:02.840
1Even if the AES-256 breaks. Getting access of my password database file is not enough as my database needs password and a local Key file to open the database. Also I checked how keepass works it never creats any unencryped swap file which can be later retrived on dropbox so it is very very safe I feel. All it creats a file which says database is unlocked. – TusharG – 2012-06-21T12:38:10.117
2@TusharG: AES-256 is being discussed as the Keepass protection; hence, if AES-256 were broken and you have the database, you don't need either the key file or the password to look at its contents.
However, the problem doesn't exist: when AES-256 will have been slowly broken, if Keepass is still well maintained it will have migrated to a different encryption standard much more than 30 days before. – Blaisorblade – 2013-07-08T09:33:22.377
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There are different degrees of security, and the convenience of Dropbox versus the security of what you're trying to do are something you'll need to evaluate for yourself.
Also, security depends upon the weakest point. If any of the following are compromised, then your files are exposed:
Consider the following and that may be able to help you make that decision:
BryanH
Posted 2011-10-28T10:41:14.223
Reputation: 169
8This all talks about Dropbox security and its encryption. However how safe is KeePass database without key file? Can anyone decrypt KeePass database without password and Key file? – TusharG – 2011-10-28T11:09:51.203
You can use the feature of a separate, additional key file: http://www.pctipp.ch/tipps-tricks/kummerkasten/sicherheit/artikel/keepass-datei-in-der-cloud-sicher-geht-das-83604/
– koppor – 2016-07-30T15:39:17.3901Passwords should not be stored where others can see them (like Dropbox). – m0skit0 – 2011-10-28T10:47:08.010
2Others cannot see my password file as Dropbox keeps file strictly with my login unless I have kept it in shared folder. – TusharG – 2011-10-28T10:52:29.640
1Dropbox server administrators? – m0skit0 – 2011-10-28T10:53:33.447
Dropbox had a major security glitch where everyone could fully access any account.
– slhck – 2011-10-28T10:59:40.0107Having a security glitch and having it as a standard feature arn't quite the same thing. Besides keepass uses its own encryption. – Sirex – 2011-10-28T14:03:56.403
Interesting, because I did the very thing for my parents to help them manage their passwords – Ivo Flipse – 2011-10-28T14:18:51.250