An alternative to encrypting full partitions or disks is to encrypt portions of a filesystem, usually a directory and everything below it in the hierarchy, by using special features of Linux so that the encryption and decryption are handled automatically by the kernel or special software in the background. Thus, there are no implications for booting (as long as the boot directory isn't encrypted) and no installation issues, as it is configured after installation. Directory encryption is appropriate for servers containing sensitive information that resides in certain parts of the directory hierarchy.
Debian provides several packages for this type of encryption. The two most common are encls and cryptsetup.
