Defensive Design

Defensive Design

1. Defensive Design is the act of anticipating every possible way that an end-user could misuse a system or device. During the defensive design process, methods are put in place to eliminate misuse. If this is not completely possible then it will aim to minimise the negative consequences

2. You know that the defensive design has not been good enough when:

   • the program crashes
   • the program behaves in an unidentified pattern.
   • data security has been compromised

3. Application software often requires a user to input information into a system.

   • A username/ password entry
   • Contact details
   • Current date
   • input into a search box
   • Building up a shopping cart
   • Entering data into a database
   • All these methods involve the most unpredictable component of any system - PEOPLE!!!

4. The first port of call in defensive design is to decide is on what kind of user interface to code for. There is a fine balancing act when giving the user access to all the information and abilities that they might need, while at the same time imposing limits on the things that they commonly get wrong.

   • A menu-driven user interface limits the user to being able to choose from a displayed list of choices.
   • The only actions that a user can perform is to use the up-down-left-right buttons on their remote control to navigate a 'select' button to select an option.
   • A menu interface can help to limit unexpected or invalid entries.
   • Another example are public booths with a touch sensitive screen.