USB Encryption that works on both Chromebook OS and Windows 7?

Hi all-

My school will be upgrading (or downgrading, depends on how you look at it) to Chromebooks, and I'm looking for a way to encrypt a USB flash drive and use it on both my school laptop (the Chromebook) and my home PC (running Windows 7). Is there any free encryption software that would work on both OSs, and not need admin privileges to encrypt/decrypt my personal files?
 


Yes. I know it does sound ridiculous, but yes. I've got good reasons to keep them encrypted, it's not like I'm hiding porno. I also don't need them super secure, just protected enough that if the drive is lost, an average Joe can't see everything I had on the drive.