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@xxxxxxxx> on behalf of Michael Kjörling <michael@xxxxxxxxxxx> Sent: Friday, December 27, 2019 1:20:11 PM To: dm-crypt@xxxxxxxx Subject: [EXTERNAL] Re: How to compress LUKS2 header? 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. 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@xxxxxxxxxxx “Remember when, on the Internet, nobody cared that you were a dog?” _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx https://urldefense.proofpoint.com/v2/url?u=https-3A__www.saout.de_mailman_listinfo_dm-2Dcrypt&d=DwIGaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=ZRo7ioNm6-KW9XMwc8-3Aqc6TBVFd8_9yk27A36m0u0&m=rQUoPqXVjthTyHfeJ02oW6vvxq9wwNPVBB1anj-N7kI&s=pg-I-9_hpvWliVyuS2yTJk_kfFNljzWR1YSIUcHluIg&e= _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx https://www.saout.de/mailman/listinfo/dm-crypt