Research and Implementation of Database Security Add-on

It was presented the development background , design and implementation techniques of a database security add-on . There were some de- fects in discretionary access control , to solve these problems , the database security add-on realizea mandatory access control model, which could make datbase management system of C level having important characteristicsof B level of TCSEC (Trusted Computer System Evaluation Criteria) and TDI (Trusted Database Interpretation) .