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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 :)
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.
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.