This course explores the design principles that help to ensure key security practices are incorporated into the software development lifecycle, and it prepares you for the (ISC)2 CSSLP (Certified Secure Software Lifecycle Professional) exam. The design principles you will learn include least privilege, to provide the lowest level of rights and permissions for a user to perform current tasks and separation of duties. This course covers the principles of defense in depth, to include multiple overlapping defenses such as layered controls, input validation, and security zones that work together collectively as a series of defenses. You will learn the concepts of fail-safe principles, including exception handling, and denied by default. Next, learn to design a complete mediation so that authorization is verified every time access is requested. Also covered is a less common design issue is psychological acceptability, such as password complexity and screen layouts, to ensure the design is psychologically acceptable to users. Finally, this course examines the separation of duties principles, including multiparty control, secret sharing and splitting.