Security Principles in the Software Lifecycle
Security at every stage of the SDLC
Secure development isn't a phase, but a set of practices that runs through the entire software development lifecycle (SDLC), from requirements to maintenance in production. In requirements and design, controls are defined and threats are modeled; in coding, secure standards and code review are applied; in testing, static and dynamic analysis is run in addition to functional tests; in deployment, the environment's secure configuration is verified; and in maintenance, patches are managed and behavior in production is monitored. The central principle is "shift left": moving security controls as early as possible in the cycle, because a defect detected in design costs a fraction of what it costs to fix the same flaw once the software is already in the hands of real users.