Page 111 - DCAP516_COMPUTER_SECURITY

Unit 9: Database Security

Logical Database Integrity: The structure of the database is preserved. With logical integrity Notes
of a database, a modification to the value of one field does not affect other fields.

Element Integrity: The data contained in each element are accurate.
Auditability: It is possible to track who or what has accessed (or modified) the elements in
the database.

Access Control: A user is allowed to access only authorized data, and different users can be
restricted to different modes of access (such as read or write).
User Authentication: Every user is positively identified, both for the audit trail and for
permission to access certain data.
Availability: Users can access the database in general and all the data for which they are
authorized.

Integrity of the Database

The data must be protected from corruption. Two situations can affect the integrity of a database:

1. When the whole database is damaged (as happens, for example, if its storage medium is
damaged)
2. When individual data items are unreadable.

Integrity of the database as a whole is the responsibility of the DBMS, the operating system, and
the (human) computing system manager. From the perspective of the operating system and the
computing system manager, databases and DBMSs are files and programs, respectively.
Therefore, one way of protecting the database as a whole is to regularly back up all files on the
system.

Element Integrity

The integrity of database elements is their correctness or accuracy. Ultimately, authorized users
are responsible for entering correct data into databases. However, users and programs make
mistakes collecting data, computing results, and entering values. Therefore, DBMSs sometimes
take special action to help catch errors as they are made and to correct errors after they are
inserted.

Auditability

For some applications it may be desirable to generate an audit record of all access (read or write)
to a database. Such a record can help to maintain the database’s integrity, or at least to discover
after the fact who had affected which values and when. A second advantage, as we see later, is
that users can access protected data incrementally; that is, no single access reveals protected data,
but a set of sequential accesses viewed together reveals the data, much like discovering the clues
in a detective novel.

Access Control

Databases are often separated logically by user access privileges. For example, all users can be
granted access to general data, but only the personnel department can obtain salary data and
only the marketing department can obtain sales data. Databases are very useful because they
centralize the storage and maintenance of data. Limited access is both a responsibility and a
benefit of this centralization.

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