On Fri, Dec 27, 2019 at 17:20:11 CET, Michael Kjörling wrote: > On 27 Dec 2019 10:56 -0500, from gebser@xxxxxxxxxxxx (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. Well, actually compressing encrypted data is very easy. It just has one mandatory condition that has to be met: You have to be able to decrypt. Moden ciphers make sure you can only do that when you have the key. > I'm pretty sure the LUKS header backup isn't compressed. It is not. Also, the anti-forensic stripes are not encyption. They are basically an all-or-nothing transformation and that is different form encryption. Regards, Arno > -- > Michael Kjörling • https://michael.kjorling.se • michael@xxxxxxxxxxx > “Remember when, on the Internet, nobody cared that you were a dog?” > > _______________________________________________ > dm-crypt mailing list > dm-crypt@xxxxxxxx > https://www.saout.de/mailman/listinfo/dm-crypt -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@xxxxxxxxxxx GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- A good decision is based on knowledge and not on numbers. -- Plato If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx https://www.saout.de/mailman/listinfo/dm-crypt
