I know it might seem a bit too much theoretical, but I was wondering if there was some list of known open problems in security?
In a similar way that there are open problems in Theoretical Computer Science: http://cstheory.stackexchange.com/questions/174/major-unsolved-problems-in-theoretical-computer-science, it would be interesting to get a similar list in security, especially for research purposes.
Note that I am particularly interested in theoretical/research problems, rather than concrete usage or implementation problems, as those given in this list: What are the biggest unsolved problems in IT Security?.
Any idea/suggestion/comment is welcome, this is just question that came up to my mind after a panel discussion at a security conference.
EDIT: As pointed out by Thomas, I'm more interested here on non-crypto problems, such as those involving policies, enforcement mechanisms, etc.