Secure by design, in software engineering, means that software products and capabilities have been designed to be foundationally secure. Alternate security strategies, tactics and patterns are considered at the beginning of a software design, and the best are selected and enforced by the architecture, and they are used as guiding principles for developers. It is also encouraged to use strategic design patterns that have beneficial effects on security, even though those design patterns were not originally devised with security in mind. Secure by Design is increasingly becoming the mainstream development approach to ensure security and privacy of software systems. In this approach, security is considered and built into the system at every layer and starts with a robust architecture design. Security architectural design decisions are based on well-known security strategies, tactics, and patterns defined as reusable techniques for achieving specific quality concerns. Security tactics/patterns provide solutions for enforcing the necessary authentication, authorization, confidentiality, data integrity, privacy, accountability, availability, safety and non-repudiation requirements, even when the system is under attack. In order to ensure the security of a software system, not only is it important to design a robust intended security architecture but it is also necessary to map updated security strategies, tactics and patterns to software development in order to maintain security persistence. Expect attacks Malicious attacks on software should be assumed to occur, and care is taken to minimize impact. Security vulnerabilities are anticipated, along with invalid user input. Closely related is the practice of using "good" software design, such as domain-driven design or cloud native, as a way to increase security by reducing risk of vulnerability-opening mistakes—even though the design principles used were not originally conceived for security purposes. Avoid security through obscurity Generally, designs that work well do not rely on being secret. Often, secrecy reduces the number of attackers by demotivating a subset of the threat population. The logic is that if there is an increase in complexity for the attacker, the increased attacker effort to compromise the target will discourage them. While this technique implies reduced inherent risks, a virtually infinite set of threat actors and techniques applied over time will cause most secrecy methods to fail. While not mandatory, proper security usually means that everyone is allowed to know and understand the design because it is secure. This has the advantage that many people are looking at the computer code, which improves the odds