Secure Software Requirements

In the Certified Secure Software Lifecycle Professional (CSSLP) body of knowledge, Secure Software Requirements is the domain focused on identifying, documenting, and validating the security needs of software before design and coding begin. The core premise is that security must be built in from the start rather than bolted on later, because defects discovered in requirements are far cheaper to fix than those found in production. This domain begins with gathering security requirements from multiple sources. Functional security requirements describe what the software must do to protect itself and its data, such as authentication, authorization, auditing, session management, and input validation. Non-functional requirements address qualities like confidentiality, integrity, availability, privacy, and resilience. Requirements also derive from legal, regulatory, and compliance obligations (for example GDPR, HIPAA, PCI DSS), from organizational policies and standards, and from industry frameworks. Key techniques include data classification, which determines how sensitive information must be protected throughout its lifecycle; privacy requirements analysis, including data minimization and retention rules; and the use of misuse cases and abuse cases, which describe how an attacker might exploit the system, complementing traditional use cases. Threat modeling often begins here to anticipate risks early. Subject-object-activity matrices help define who can perform what actions on which resources. Requirements must be clear, testable, traceable, and prioritized. A Requirements Traceability Matrix links each security requirement to its source, design element, implementation, and test case, ensuring nothing is lost across the lifecycle. Acceptance criteria define how each requirement will be verified. Finally, the domain emphasizes stakeholder collaboration among business owners, developers, security teams, legal, and operations so requirements reflect real risk tolerance. Well-defined secure requirements reduce vulnerabilities, support compliance, lower remediation costs, and establish the foundation for secure design, implementation, testing, and deployment throughout the software lifecycle. In the Certified Secure Software Lifecycle Professional (CSSLP) body of knowledge, Secure Software Requirements is the domain focused on identifying, documenting, and validating the security needs of software before design and coding begin. The core premise is that security must be built in from th…