[dm-crypt] Security concern: gpg keyfile vs passphrase
arno at wagner.name
Tue Jul 7 23:20:07 CEST 2015
I think a keyfile is only better if it resides in a different
place than the LUKS header, i.e. is on an USB stick that gets
removed or the like and can hence act as an extra factor.
Crtypto-wise, if yoy use a high-entropy passphrase,see
FAQ Item 5.1 at
...I do not see any reason why using GnuPG to protect the
passhrase would be any more secure.
On Tue, Jul 07, 2015 at 23:08:17 CEST, lyz wrote:
> The keyfile will be stored in the /boot partition.
> My question is if it's in a cryptographic way more secure, like if gpg
> encryption of a keyfile is more difficult to break rather than a
> dm-crypt encryption of a device, therefore it's logical to use a keyfile
> to encrypt the device and gpg to encrypt the keyfile.
> On 07/07/2015 10:52 PM, wintonian wrote:
> > A quick guess,
> > In this scenario you have the following:-
> > A, something physical - i.e. a keyfile.
> > plus
> > B, something known - i.e. a pass phrase.
> > Which equals something more secure
> > I guess there might be more to it than that, but I assume that's part of
> > it.
> > Regards
> > Robert
> > On 07/07/15 21:32, lyz wrote:
> >> Hi all,
> >> I'm encrypting my whole system under LUKS, and I've seen that in the
> >> wiki of Arch and Gentoo they suggest to use a keyfile and encrypt it
> >> with gpg.
> >> Why is more secure to encrypt a keyfile with a passphrase and then
> >> encrypt the device with the keyfile rather than encrypting the device
> >> directly with the passphrase?
> >> Against a brute force attack the passphrase is the same, so they should
> >> be equally secure, am I wrong?
> >> Thank you
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Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno at wagner.name
GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718
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