Re: How to compress LUKS2 header?

"Julio Cesar Faracco - [email protected]" <[email protected]>
Newsgroups gmane.linux.kernel.device-mapper.dm-crypt
Message-ID <[email protected]>
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 <[email protected]> on behalf of Michael Kjörling <michael-/[email protected]>
Sent: Friday, December 27, 2019 1:20:11 PM
To: [email protected]
Subject: [EXTERNAL] Re: [dm-crypt] How to compress LUKS2 header?
    
On 27 Dec 2019 10:56 -0500, from gebser-Qz+AbkVSZgBWk0Htik3J/[email protected] (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=  • [email protected]
 “Remember when, on the Internet, nobody cared that you were a dog?”

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