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From: Heinz Diehl <htd@fancy-poultry.org>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] luksFormat Password Entropy
Date: Sat, 21 Aug 2010 09:30:25 +0200	[thread overview]
Message-ID: <20100821073025.GA7167@fancy-poultry.org> (raw)
In-Reply-To: <20100819183532.GB22363@tansi.org>

On 19.08.2010, Arno Wagner wrote: 

> > So if you choose base64, P will always be 64, 
 
> No, actually, the input can restrict P to something smaller.

I don't think you're right. If the input doesn't lead to the use of 
all of the chars available in base64, so does it "choose" from this pool 
anyway. P is the amount of possibly available chars and is unrelated 
to how many different ones out of this pool actually are used. To
bruteforce the password, you'll have to try all the 64 possibilities for
each position (ok, statistically you'll have to try 50% of the whole
headroom).

If you e.g. build a password which uses 5 numbers, P is 10 [0-9].
A password out of 5 capital letters, P = 26 [A-Z]. For each of the
positions ("slots") in the password, there are 10 different possibilities 
related to the first, and 26 to the second password.

  reply	other threads:[~2010-08-21  7:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-18 20:11 [dm-crypt] luksFormat Password Entropy Michael Matczynski
2010-08-19 13:54 ` Arno Wagner
2010-08-19 14:28 ` Heinz Diehl
2010-08-19 15:23   ` Heinz Diehl
2010-08-19 18:35   ` Arno Wagner
2010-08-21  7:30     ` Heinz Diehl [this message]
2010-08-21 17:41       ` Arno Wagner

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