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Re: /dev/random5



On 3/08/2014 10:48 PM, Bzzzz wrote:
> On Sun, 03 Aug 2014 18:20:19 +1000
> I do not agree with that because using only zeros makes
> the result part predictable for the attacker: if he knows
> what you wrote, he has a (very) large part of the 
> cryptanalysis done…
> This is 1.0.1 of cryptanalysis: if you know what's encrypted
> you'll know how it was done.

Yes, but the method of encryption used (aes-xts-plain64) does NOT lend
itself to this kind of analysis.  The cryptsetup FAQ documentation
covers my use of /dev/zero .... we've had this discussion before ;-)

https://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#2._Setup

See step 6, there is an earlier write of /dev/zero at step 3, but I
think that is pointless unless you don't do the optional one at step 6.

btw aes-xts-plain64 (for 2TB+ sized drives) is the default for version
1.6.0 onwards, but Debian stable is using version 1.4.3 at this time.

Just don't use defaults; case in point is using the CAST5 cipher for
symmetric encryption with gpg ... what a joke that default is!

Cheers
A.

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