♦ Countermeasures - computer based controls-

▪ Authorization The granting of a right or privilege, which enables a subject to legitimately have access to a system or a system’s object.

▪ Authentication A mechanism that determines whether a user is who he or she claims to be.

▪ View Dynamic result of one or more relational operations operating on the base relations to produce another relation. A virtual relation that does not actually exist in the database, but is produced upon request by a particular user, at the time of request.

2. Countermeasures

♦ Countermeasures - computer based controls-

▪ Backup Process of periodically taking a copy of the database and log file

(and possibly programs) to offline storage media.

▪ Journalizing Process of keeping and maintaining a log file (or journal) of all changes made to database to enable effective recovery in event of failure. ▪ Integrity Prevents data from becoming invalid, and hence giving misleading

or incorrect results.

2. Countermeasures

♦ Countermeasures - computer based controls-

▪ Encryption The encoding of the data by a special algorithm that renders the

data unreadable by any program without the decryption key.

▪ Raid (redundant array of independent disks) technology One solution is to provide a large disk array comprising an arrangement of several independent disks organized to improve reliability and increase performance. - Performance is increased through data striping. Reliability is improved through storing redundant information across the disks using a parity scheme or an error-correcting scheme.

2. Countermeasures

♦ Countermeasures - computer based controls-

▪ User-defined procedures Some DBMSs also provide capabilities for user-defined procedures to customize the authorization process

▪ Check point DBMS periodically refuses to accept new transactions system is in a quiet state Database and transaction logs are synchronized.

2. Countermeasures

♦ Database Failure Responses

▪ Aborted transactions Preferred recovery: rollback Alternative: roll forward to state just prior to abort

▪ Incorrect data Preferred recovery: rollback Alternative 1: re-run transactions not including inaccurate data updates Alternative 2: compensating transactions

3. Database Failure Responses

♦ Database Failure Responses

▪ System failure (database intact) Preferred recovery: switch to duplicate database Alternative 1: rollback Alternative 2: restart from checkpoint

▪ Database destruction Preferred recovery: switch to duplicate database Alternative 1: roll forward Alternative 2: reprocess transactions

3. Database Failure Responses