Which filesystem to use when a samba share should allow for NTFS encryption?

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http://unix.stackexchange.com – I'm using a NAS (Buffalo LinkStation Pro with SSH access, if that matters) which runs Linux ( #1 Fri Jun 8 11:07:30 JST 2012 armv5tel GNU/Linux, with smbd --version = Version 3.0.30-1.4.osstech), while all clients run Windows 7. Currently, the shares are on a xfs partition. How can samba be modified such that the share behaves like an NTFS share to the clients, i.e. allowing for encryption? Or do I need to reformat the partition as an NTFS drive (or more likely, use a loop-mounted NTFS file)? (HowTos)