CLONING/IMAGING: If you clone or image a LUKS container, you make a copy of the LUKS header and the master key will stay the same! That means that if you distribute an image to several machines, the same master key will be used on all of them, regardless of whether you change the passphrases. Do NOT do this! If you do, a root-user on any of the machines with a mapped (decrypted) container or a passphrase on that machine can decrypt all other copies, breaking security. See also Item 6.15.
So: I have a notebook "A" (a Linux Desktop installed with LUKS & and I have root access to it) and I clone the whole disk of it to notebook "B", and the notebook "B" had it's LUKS password changed.
My question: How can I mount/decrypt notebook "B" LUKS partition with ONLY the known master key from "A"?* (and I know the cipher type too)
*UPDATE: What are the exact commands to mount the B's HDD on A?