From: "Julio Cesar Faracco - jfaracco@br.ibm.com" <jfaracco@br.ibm.com>
To: "dm-crypt@saout.de" <dm-crypt@saout.de>
Subject: Re: [dm-crypt] How to compress LUKS2 header?
Date: Fri, 27 Dec 2019 20:46:50 +0000 [thread overview]
Message-ID: <65f0e9b350cd4e9bb418c8d87e4333fe@br.ibm.com> (raw)
In-Reply-To: <xcsvcvspcwrfkq9qvp4d9nqh@localhost>
Thanks for your suggestions, guys...
Do you have any recommendation to reduce this header size then?
Imagine 1000 lab machines.. They are taking 20 GB to backup each header.
Revert to LUKS v1 type is not a possibility.
I appreciate your help...
--
Julio Cesar Faracco
From: dm-crypt <dm-crypt-bounces@saout.de> on behalf of Michael Kjörling <michael@kjorling.se>
Sent: Friday, December 27, 2019 1:20:11 PM
To: dm-crypt@saout.de
Subject: [EXTERNAL] Re: [dm-crypt] How to compress LUKS2 header?
On 27 Dec 2019 10:56 -0500, from gebser@mousecar.com (ken):
> Compressing a file is one step in the encryption of that file. So if
> your LUKS2 header file is encrypted, it's also already compressed.
> Using ZIP on it would yield no further compression.
No, encryption does not imply compression. Rather, trying to compress
ciphertext is a largely pointless exercise if the encryption is any
good in the first place; therefore, _if_ you're going to compress the
data you're encrypting (keeping in mind that doing so is not always a
good idea; see compression oracle attacks), then you need to compress
first, then encrypt, not the other way around.
I'm pretty sure the LUKS header backup isn't compressed.
--
Michael Kjörling • https://urldefense.proofpoint.com/v2/url?u=https-3A__michael.kjorling.se&d=DwIGaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=ZRo7ioNm6-KW9XMwc8-3Aqc6TBVFd8_9yk27A36m0u0&m=rQUoPqXVjthTyHfeJ02oW6vvxq9wwNPVBB1anj-N7kI&s=worTWmhb84zgfP27r3HYCW1CSw9M_93ZnC2rb_81SfQ&e= • michael@kjorling.se
“Remember when, on the Internet, nobody cared that you were a dog?”
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next prev parent reply other threads:[~2019-12-27 20:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-23 14:41 [dm-crypt] How to compress LUKS2 header? Julio Faracco
2019-12-27 15:56 ` ken
2019-12-27 16:20 ` Michael Kjörling
2019-12-27 16:27 ` Arno Wagner
2019-12-27 20:46 ` Julio Cesar Faracco - jfaracco@br.ibm.com [this message]
2019-12-27 21:19 ` Milan Broz
2019-12-28 0:20 ` Arno Wagner
-- strict thread matches above, loose matches on Subject: below --
2019-12-26 20:12 Julio Cesar Faracco - jfaracco@br.ibm.com
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