Research On Isolation And Repair Technology In Security Database Based On User Dependency Model

With the rapid development of information technology, applications of the database have obtained an enormous popularization. As important data stored center of information systems, database has always been attack target. Traditional prevention centric database security mechanisms put emphases on inspection of user identification and permission constraints. Therefore, existing transaction based intrusion detection, isolation and recovery mechanisms are very limited to prevent all attacks and abuses of inner normal users.In this paper, based on the research on existing database security mechanisms, we propose the user dependency model with timestamps, which mainly focuses on the damage of the malicious attacks. And on the basis of the user dependency model, we also propose the algorithm of the intrusion isolation and repair of the security database, then design and implement the intrusion isolation and repair module in the security DBMS—NHSecure. The main contents and innovations of this thesis are as follows:(1) Based on the analysis of the existing transaction and data dependency model, focuses on the database system users, proposes the user dependency model with the timestamps and the algorithm of building the user dependency model on the fly. Simulated experiments show the feasibility of space and time cost of the algorithm.(2) Based on the user dependency model, proposes the real time isolation strategy and methods of the database system after malicious attacks. Simulated experiments show that the algorithm was well to meet the requirements of the space and time cost.(3) By maintaining the before images of the data items and improving the traditional undo and redo operations, the improved database system repair algorithm reduces time cost largely, while there is no large increase in required disk space.(4) Designs and implements the intrusion isolation and repair module of security DBMS—NHSecure, including the data structure design and the concrete implementation method.