Differentiate Authentication and Authorization

Authentication is the mechanism whereby systems may securely identify their users. Authentication systems provide an answers to the questions:

• Who is the user?
• Is the user really who he/she represents himself to be?

Authorization, by contrast, is the mechanism by which a system determines what level of access a particular authenticated user should have to secured resources controlled by the system. For example, a database management system might be designed so as to provide certain specified individuals with the ability to retrieve information from a database but not the ability to change data stored in the database, while giving other individuals the ability to change data. Authorization systems provide answers to the questions:

• Is user X authorized to access resource R?
• Is user X authorized to perform operation P?
• Is user X authorized to perform operation P on resource R?