I used ecryptfs to encrypt my home and the swap.
Now I have a device /dev/mapper/cryptswap1 which seems to act as the swap.
(by the way, how can I confirm that?)
Before, my swap was in a partition of its own, sda7. Now, this partition is shown unused by Gparted (0.00b used).
Therefore I'm wondering if cryptswap1 is located in sda7 or in sda6, which is my ubuntu partition.