I tried the following

sudo cryptsetup luksChangekey /dev/nvme0n1p3 < new passphrase >

It then asks for the Sudo password, then asks for the old passphrase, but then it prints this error message

Failed to open key file.

what went wrong ?

Edit: turns out using GNOME Disks is way more straightforward.. 😅, thank you all

  • NoamParenti [they/them]
    ·
    29 days ago

    The correct syntax is cryptsetup luksChangeKey <device> <key file>. So what you tried is opening a file that is named like your new passphrase. Such a file of course (hopefully) doesn't exist.

    Just omit the last parameter, i.e. sudo cryptsetup luksChangekey /dev/nvme0n1p3 and enter the new password when it asks you to.