Re: strange behavior in the permissions of d/ling a file
Are you usuing TIKI's HTML pages or your own?
If you're using your own, you might consider switching or using the tikiIntegrator to integrate them. (Personally I'd recommend tiki's HTML pages for the most part and iframes to get anything you can't embed - that way tiki will be able to place permissions on your html pages too).
Otherwise I think the curse-word you're looking for is probably "LDAP" 
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