* [dm-crypt] How to compress LUKS v2 header? @ 2019-12-26 20:20 Julio Cesar Faracco - jfaracco@br.ibm.com 2019-12-26 21:38 ` Michael Kjörling 2019-12-27 9:30 ` Arno Wagner 0 siblings, 2 replies; 4+ messages in thread From: Julio Cesar Faracco - jfaracco@br.ibm.com @ 2019-12-26 20:20 UTC (permalink / raw) To: dm-crypt Hi all, I'm trying to compress a LUKS v2 header file, but I'm not seeing any sensible reduction. I'm using `cryptsetup luksHeaderBackup /dev/sda2 --header-backup-file /tmp/backup.header` I used ZIP and GZIP, but I got 0% of reduction of `backup.header`. :-( Do you have any suggestions of what algorithm should be used to compress this type of file? Thanks! -- Julio Cesar Faracco ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dm-crypt] How to compress LUKS v2 header? 2019-12-26 20:20 [dm-crypt] How to compress LUKS v2 header? Julio Cesar Faracco - jfaracco@br.ibm.com @ 2019-12-26 21:38 ` Michael Kjörling 2019-12-27 9:30 ` Arno Wagner 1 sibling, 0 replies; 4+ messages in thread From: Michael Kjörling @ 2019-12-26 21:38 UTC (permalink / raw) To: dm-crypt On 26 Dec 2019 20:20 +0000, from jfaracco@br.ibm.com (Julio Cesar Faracco - jfaracco@br.ibm.com): > I'm using `cryptsetup luksHeaderBackup /dev/sda2 --header-backup-file /tmp/backup.header` > I used ZIP and GZIP, but I got 0% of reduction of `backup.header`. :-( > Do you have any suggestions of what algorithm should be used to > compress this type of file? Why are you trying to compress the header backup in the first place? As a general rule, encrypted data (such as the parts of the LUKS header that aren't already random by design) does not compress well; if data that has been encrypted can be compressed to any notable degree, that usually means the encryption is somehow flawed, because it's leaving patterns in the encrypted data. Properly encrypted data should look completely random, which means that there's very little, if anything, for compression utilities to find reducible patterns in. -- Michael Kjörling • https://michael.kjorling.se • michael@kjorling.se “Remember when, on the Internet, nobody cared that you were a dog?” ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dm-crypt] How to compress LUKS v2 header? 2019-12-26 20:20 [dm-crypt] How to compress LUKS v2 header? Julio Cesar Faracco - jfaracco@br.ibm.com 2019-12-26 21:38 ` Michael Kjörling @ 2019-12-27 9:30 ` Arno Wagner 2019-12-27 13:37 ` Julio Cesar Faracco - jfaracco@br.ibm.com 1 sibling, 1 reply; 4+ messages in thread From: Arno Wagner @ 2019-12-27 9:30 UTC (permalink / raw) To: dm-crypt Hi, compressing the anti-forensic stripes would require breaking some pretty impressive crypto. In short, for all practical purposes, compression is impossible. Regards, Arno On Thu, Dec 26, 2019 at 21:20:44 CET, Julio Cesar Faracco - jfaracco@br.ibm.com wrote: > Hi all, > > I'm trying to compress a LUKS v2 header file, but I'm not seeing any > sensible reduction. > I'm using `cryptsetup luksHeaderBackup /dev/sda2 --header-backup-file /tmp/backup.header` > I used ZIP and GZIP, but I got 0% of reduction of `backup.header`. :-( > Do you have any suggestions of what algorithm should be used to > compress this type of file? > > Thanks! > > -- > Julio Cesar Faracco > _______________________________________________ > dm-crypt mailing list > dm-crypt@saout.de > https://www.saout.de/mailman/listinfo/dm-crypt -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [dm-crypt] How to compress LUKS v2 header? 2019-12-27 9:30 ` Arno Wagner @ 2019-12-27 13:37 ` Julio Cesar Faracco - jfaracco@br.ibm.com 0 siblings, 0 replies; 4+ messages in thread From: Julio Cesar Faracco - jfaracco@br.ibm.com @ 2019-12-27 13:37 UTC (permalink / raw) To: Arno Wagner, dm-crypt [-- Attachment #1: Type: text/plain, Size: 2430 bytes --] Hi guys! Thanks for your answers and sorry to send a lots of cloned emails. I got issues to send for some reason. Anyway, we have a lab here and we usually save the backup header for security reasons. But after moving to LUKS v2 from v1, header increased from ~1MB to ~22MB. We would not like to remove some important features introduced by v2. -- Julio Cesar Faracco From: dm-crypt <dm-crypt-bounces@saout.de> on behalf of Arno Wagner <arno@wagner.name> Sent: Friday, December 27, 2019 6:30 AM To: dm-crypt@saout.de Subject: [EXTERNAL] Re: [dm-crypt] How to compress LUKS v2 header? Hi, compressing the anti-forensic stripes would require breaking some pretty impressive crypto. In short, for all practical purposes, compression is impossible. Regards, Arno On Thu, Dec 26, 2019 at 21:20:44 CET, Julio Cesar Faracco - jfaracco@br.ibm.com wrote: > Hi all, > > I'm trying to compress a LUKS v2 header file, but I'm not seeing any > sensible reduction. > I'm using `cryptsetup luksHeaderBackup /dev/sda2 --header-backup-file /tmp/backup.header` > I used ZIP and GZIP, but I got 0% of reduction of `backup.header`. :-( > Do you have any suggestions of what algorithm should be used to > compress this type of file? > > Thanks! > > -- > Julio Cesar Faracco > _______________________________________________ > dm-crypt mailing list > dm-crypt@saout.de > https://urldefense.proofpoint.com/v2/url?u=https-3A__www.saout.de_mailman_listinfo_dm-2Dcrypt&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=ZRo7ioNm6-KW9XMwc8-3Aqc6TBVFd8_9yk27A36m0u0&m=UHeTRaj2fJOS8eofLbCuddNDYr5YBFfte5x52g8cOh0&s=whK0QtntH0C5Yob4nwEPjwFCu8n7NZirV09FpwE_pbg&e= -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name 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@saout.de https://urldefense.proofpoint.com/v2/url?u=https-3A__www.saout.de_mailman_listinfo_dm-2Dcrypt&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=ZRo7ioNm6-KW9XMwc8-3Aqc6TBVFd8_9yk27A36m0u0&m=UHeTRaj2fJOS8eofLbCuddNDYr5YBFfte5x52g8cOh0&s=whK0QtntH0C5Yob4nwEPjwFCu8n7NZirV09FpwE_pbg&e= [-- Attachment #2: OutlookEmoji-LinkedIn: http://br.linkedin.com/pub/julio-faracco/43/681/397a14dc823-fa70-4daf-9c4a-6c30766f5b4c.png --] [-- Type: image/png, Size: 962 bytes --] [-- Attachment #3: OutlookEmoji-Blogger: http://juliofaracco.blogspot.com.br/0e6de5db-b412-4200-865d-86db869c9bb9.png --] [-- Type: image/png, Size: 802 bytes --] [-- Attachment #4: OutlookEmoji-Facebook: http://www.facebook.com/julio.faracco60a4f116-25ec-4719-8a4e-d762fac8af7b.png --] [-- Type: image/png, Size: 843 bytes --] [-- Attachment #5: OutlookEmoji-IBMd7b60b1a-033c-4418-aa5e-5d77782d59b8.png --] [-- Type: image/png, Size: 434 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-12-27 13:37 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-12-26 20:20 [dm-crypt] How to compress LUKS v2 header? Julio Cesar Faracco - jfaracco@br.ibm.com 2019-12-26 21:38 ` Michael Kjörling 2019-12-27 9:30 ` Arno Wagner 2019-12-27 13:37 ` Julio Cesar Faracco - jfaracco@br.ibm.com
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