Composite BW security system

Hi,

I am trying a develop a security system . where i need to restrict the material depending upon the customer.

EX: user1 can access customer A and material C,D,E.same user can access customer B and material C,D.

ie, When cutomer A is choosen he can view 3 materials C,D,E. andd when customer B is choosen he can view only 2 materials C and D.

Did any one worked with such type of scenarios in Secirity. Can i have any hint for this design.

Thanks,

Ramkumar.