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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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I apologise if this is already common knowledge, but I just found out you can have multiple layers of LUKS encryption on a drive! (lemmy.ml)

submitted 7 months ago by [email protected] to c/[email protected]

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[Image description:
Screenshot of terminal output:

~ ❯ lsblk
NAME           MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
sda              8:0    1  62.5M  0 disk  
└─topLuks      254:2    0  60.5M  0 crypt 
  └─bottomLuks 254:3    0  44.5M  0 crypt

/end image description]

I had no idea!

If anyone else is curious, it's pretty much what you would expect:

cryptsetup -y -v luksFormat /dev/sda
cryptsetup open /dev/sda topLuks
cryptsetup -y -v luksFormat /dev/mapper/topLuks
cryptsetup open /dev/mapper/topLuks bottomLuks
lsblk

Then you can make a filesystem and mount it:

mkfs.ext4 /dev/mapper/bottomLuks
mount /dev/mapper/bottomLuks ~/mnt/embeddedLuksTest

I've tested putting files on it and then unmounting & re-encrypting it, and the files are indeed still there upon decrypting and re-mounting.

Again, sorry if this is not news to anyone else, but I didn't realise this was possible before, and thought it was very cool when I found it out. Sharing in case other people didn't know and also find it cool :)

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[–] [email protected] 2 points 7 months ago (1 children)

What circumstances would that be? I can't see the use case doe this, but I'm open to see how and when that would be needed.

[–] [email protected] 2 points 7 months ago

There's a Wikipedia article on multiple encryption that talks about this, but the arguments are not that compelling to me.

The main thing is mostly about protecting your data from flawed implementations. Like, AES has not been broken theoretically, but a particular implementation may be broken. By stacking implementations from multiple vendors, you reduce the chance of being exposed by a vulnerability in one of them.

That's way overkill for most businesses. That's like nation state level paranoia.