Idea (Crazy, Could work)

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12 Sep, 2014 07:58 PM

Hello, I've been thinking over, Why not remove the password authentication (Basicly log in using any password). Why? It'll be much harder to brute force, You can log in using any password if forced, You can use different passwords for the same user, However you could have a problem remembering the password, Because you can enter anything, But if you enter the correct password you'll probably remember, "This is correct, Because i remember the password for my apple!", It does have Other downsides but i'd love to Hear you're opinion of this.

  1. Support Staff 1 Posted by Maarten Billemo... on 12 Sep, 2014 08:37 PM

    Maarten Billemont's Avatar

    Hi hhhkko5,

    Thanks for your thoughts!

    Here's the thing: when somebody wants to brute-force your master password, they wouldn't be using your Master Password app for it on your phone or Mac, but simply be running a custom implementation of the algorithm on their own powerful and expensive cluster.

    There are two ways an attacker could go about attacking your master password:

    1. Master password search with site password: If an attacker knows one of your site's passwords, he could try guessing your master password by trying all sorts of different master password combinations and seeing which one yields your password for the site. Master Password was specifically engineered to make this extremely difficult but more importantly, expensive. Master Password uses a scrypt key derivation pass that is intended specifically to slow down an attacker's generation of site passwords from a master password guess from several billion per second to only 3 guesses per second. If you choose a master password that's 6 alphanumeric characters, that means he has 12 billion master passwords to try at a rate of 3 per second, leaving him with an estimate of 133 years to crack your password. If you make your master password a bit more complex, his time and cost requirements explode off the charts.

    2. Master key search with key ID: And this is what you are referring to in your proposal. Master Password currently recognizes whether your master password was entered correctly by storing a SHA256 hash of the master key. If an attacker can somehow obtain this hash (called, the key ID) from your device, he could mount an attack and try to guess the master key instead of the master password. In doing so, he would be able to bypass the expensive scrypt step. Let's calculate the expense involved in doing this: Master Password has deliberately chosen a master key that's 64 bytes. As a result, an attacker would have to make 6277101735386680763835789423207666416102355444464034512896 guesses to find your master key, but these guesses are much faster to perform than the 3/s master password guesses from the first attack. In fact, a $5000 cluster could perform about 12 million master key guesses per second. What's the math on that? Well, this attacker's estimate for finding your master key is about 16553994299963990052001805305020348873001 years ('(8^64 / 12328000000)/3600/24/356'). So in the end, it looks like this attack isn't actually any better than the first.

    With the above I've tried to illustrate that Master Password was specifically engineered to keep your master password safe, even in the event that somebody is able to steal your phone and download the information on it. With that, it wouldn't really be worth it to drop the check on whether your master password is correct, as it doesn't really add any real insecurity.

    Let me know if you have any additional comments, thoughts or suggestions!


  2. Maarten Billemont closed this discussion on 12 Sep, 2014 08:37 PM.

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