Find out the UUID of the encrypted partition

cat /etc/crypttab

It will show something like this:

nvme0n1p3_crypt UUID=49c18a64-fc5d-4d90-b770-bfeda8531f7f none luks,discard

Find the ID of the drive

sudo blkid | grep 49c18a64

It will show something like this:

/dev/nvme0n1p3: UUID="49c18a64-fc5d-4d90-b770-bfeda8531f7f" TYPE="crypto_LUKS" PARTUUID="f47c4836-ba21-498c-a571-daea2ab0a52f"

Add a new passphrase

Important! Please keep at least one passphase before removing last passphrase!

sudo cryptsetup luksAddKey /dev/nvme0n1p3

Remove a passphrase

sudo cryptsetup luksRemoveKey /dev/nvme0n1p3

Source

How to change the password of an encrypted LVM system (previously alternate Installation, now advanced feature)?
I installed Ubuntu 11.10 with the alternate CD and encrypted the whole system (except boot) with the encrypted LVM. Update 2020: Encrypted LVM can be selected at the Installation type step of the U...