Use encapsulation

Description
Draw strong boundaries among application elements, including modules, functions and data, to limit the impact of potential attacks.

Examples

 * Design
 * Separate internal administrator's functions from external users' functions
 * Differentiate between validated data and unvalidated data, between one user's data and another's, or between data users are allowed to see and data that they are not.
 * In a web browser ensure that your mobile code cannot be abused by other mobile code.
 * Implementation
 * Hide internal details of a class, including data and methods, using private access modifier.