Oracle PL/SQL for DBAs

Using a Key for Each Row

With the second approach, a different key is used for each row of a table, as shown in Figure 4-4. This approach is far more secure than the one discussed in the previous

Figure 4-3. Single database-key approach

section. Even if a thief succeeds in stealing a key, only one row will be compromised, not the entire table or the database. There are some disadvantages of this approach: the proliferation of keys makes it extremely difficult to manage them. Also, because encryption and decryption operations need to generate or retrieve a different key for each row, performance will suffer. Nevertheless, the added security provided by this approach makes it preferable in most encryption systems.