A Cryptographic Mechanism for Object-Instance-based Authorization in Object-Oriented Database Systems - Ahmad Baraani-Dastjerdi; Josef Pieprzyk; Reihaneh Safavi-naini; Janusz R. Getta; The Pennsylvania State University CiteSeerX Archives (ftp://ftp.cs.uow.edu.au/pub/papers/1995/tr-95-01.ps.Z, 1995)