TL/DR: how to use NTFS permissions to prevent all users on other PCs from accessing a particular folder on an NTFS USB key?
I have an NTFS formatted USB key. The top level contains a single folder named "MAIN". There's an arbitrary hierarchy of many more files and folders in and below MAIN.
All these files and folders are created by a single non-admin user "FRED", on a single PC "MYPC". So MAIN, and everything in and below it, is owned by non-admin user FRED on MYPC.
There's nothing special about FRED, or MYPC. MYPC is a default Windows 7 Starter Edition netbook. FRED is a normal non-admin user on that netbook.
I want to make the minimum number of ACL changes possible, to MAIN, and preferably only to MAIN, to achieve two things:
(1) Prevent all users on other PCs from accessing MAIN at all. By "access" I mean, even just view the content thereof. So on MYPC, FRED and admins can access MAIN as normal, but on other PCs, no-one at all can access MAIN at all.
(2) Say FRED, on MYPC, copies something from within MAIN, to (say) MYPC's desktop, and then to a different USB key or PC. I'd like the copied thing to not be restricted as described above. That is, users on other PCs can access the copied thing, or not, in the same way which would have occurred if (1) had never been done in the first place.
None of these folders and files are encrypted - nor do I want them to be. So I do understand that someone could just mount the key on a non Windows system, and read-off all the raw data. That's not part of my threat model.
TIA for any suggestions!