During installation, Ubuntu now asks you if you want to encrypt your private data, including the memory swap space
When the operating system runs low on memory it uses the swap space on the drive. Some memory information could be recovered from this space after the computer has been shutdown
The swap device can be protected with Device Mapper (DM) encryption using a key randomly generated when the system is booted, since the password/key information does not need to persist between reboots LUKS is not used as it requires a persistent key.
The swap space is defined as a device mapper target in the file system table and loaded automatically on startup