From: "Michael Kjörling" <michael@kjorling.se>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] How to compress LUKS2 header?
Date: Fri, 27 Dec 2019 16:20:11 +0000 [thread overview]
Message-ID: <xcsvcvspcwrfkq9qvp4d9nqh@localhost> (raw)
In-Reply-To: <fa8394fd-74d2-d56f-af9e-654627c7ea1a@mousecar.com>
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://michael.kjorling.se • michael@kjorling.se
“Remember when, on the Internet, nobody cared that you were a dog?”
next prev parent reply other threads:[~2019-12-27 16:20 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 [this message]
2019-12-27 16:27 ` Arno Wagner
2019-12-27 20:46 ` Julio Cesar Faracco - jfaracco@br.ibm.com
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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