On 30 May 2012, at 15:09, Jonathan Thornburg wrote: > You're right, sharing of master passwords is a bad idea. But given > human nature, it happens, and a security system needs to take that > into account. There are also a lot of other ways a master password > can be compromised and thus need rolling over, e.g. shoulder-surfing, > virus keyloggers, theft of PC where web browser "remembered" it, etc. > > So... it would be a *big* plus to have a way to rollover the master > password without having to manually re-visit and re-password each > website.
If somebody gets a hold of your master password, they now have the ability to generate any password on demand. There is only one fix: Change all the passwords that the attacker can now generate. Whatever trickery you aim to do with your master password, all site passwords must be changed, either way. Since Master Password is a solution that hooks into the password authentication mechanism of arbitrary sites and it works completely offline, there is no way for it to communicate with sites on your behalf or invalidate your passwords somehow. What you're pointing out is a flaw of the decentralized password authentication mechanism, and the only fix is to stop using decentralized password authentication. It's not a terribly big deal, IMO, but if you are indeed worried about loosing your master password, you need to either start using something like OpenID exclusively or use a password solution that doesn't work statelessly and then hope you won't also loose that state to the attacker along with your master password (seems unlikely that you can protect yourself from this). A very valid point, however, is key logging. To thwart that, Master Password users could use only the iOS application, which displays their password, and copy it manually to their desktop. That would void the need to enter the master password on the desktop which may potentially be compromised. Don't get me wrong; your iPhone can also get compromised, but it's significantly less likely to happen. It's probably the most secure keypad you have around, not to mention it's much easier to keep nosey sholder-surfers away from a tiny screen you hold in your hand than a large keyboard in a fixed position on your desk.
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