Arcane Lock

The target is sealed to all creatures except those you designate (who can open the object normally). Alternatively, you may choose a password that suppresses this spell for 1 minute when it is spoken within 5 feet of the target. The spell can also be suppressed for 10 minutes by casting _knock_ on the target. Otherwise, the target cannot be opened normally and it is more difficult to break or force open, increasing the DC to break it or pick any locks on it by 10 (minimum DC 20).