Access control in a relational data base management system by query modification

This work describes the access control system being implemented in INGRES (<Underline>IN</Underline>teractive <Underline>G</Underline>raphics and <Underline>RE</Underline>trieval <Underline>S</Underline>ystem). The scheme can be applied to any relational data base management system and has several advantages over other suggested schemes. These include: a) implementation ease b) small execution time overhead c) powerful and flexible controls d) conceptual simplicity The basic idea utilized is that a user interaction with the data base is modified to an alternate form which is guaranteed to have no access violations. This modification takes place in a high level interaction language. Hence, the processing of a resulting interaction can be accomplished with no further regard for protection. In particular, any procedure calls in the access paths for control purposes, such as in [1,2], are avoided.