cross-OS transparent encryption

[Erpo]

The spanish thread on the list right now is revolving around the problem
of sharing encrypted data between WinXP and Linux. The original poster
wants to share a read/write partition between the two OSs on a laptop
and have transparent encryption of the files on that partition. 

I said that NTFS will do this (windows only) as well as dm-crypt (linux
only), but I'm stumped as far as cross-platform solutions with
compatible on-disk formats. The only suggestion I could offer was to use
FAT32 and manually encrypt and decrypt the files before using them
(yuck). Any non-spanish-speakers have suggestions?


Eric