Unlocking a LUKS device takes very long. Why?
The iteration time for a key-slot (see Section 5 for an explanation what iteration does) is calculated when setting a passphrase. By default it is 1 second on the machine where the passphrase is set. If you set a passphrase on a fast machine and then unlock it on a slow machine, the unlocking time can be much longer. Also take into account that up to 8 key-slots have to be tried in order to find the right one. If this is problem, you can add another key-slot using the slow machine with the same passphrase and then remove the old key-slot. The new key-slot will have an iteration count adjusted to 1 second on the slow machine. Use luksKeyAdd and then luksKillSlot or luksRemoveKey. However, this operation will not change volume key iteration count (MK iterations in output of “cryptsetup luksDump”). In order to change that, you will have to backup the data in the LUKS container (i.e. your encrypted data), luksFormat on the slow machine and restore the data. Note that in the original LUKS s
