Just got a 16 GB PNY flash drive from Wal-Mart and formatted it to ext4. Any idea how I could put access security on the drive? I would prefer security to protect against other OSs as well. Thanks.
You can use cryptsetup: http://code.google.com/p/cryptsetup/
Here there is a tutorial for external drives:
As cereal mentions, to do this you need to encrypt the drive. There are a number of tools to do this, including TruCrypt: http://www.truecrypt.org/
Is there a danger of data loss when encrypting information?